Category: Tech Tips

If you live in a dry climate, a humidistat is pretty straight forward; it just turns a humidifier on and off. That’s about as simple as it gets.

If you are in a humid climate, some people have taken to wiring in humidistats as dehumidistats to help control humidity when they are away.

The first thing that must be said is;

If you want to truly control humidity along with cooling for comfort get a system and thermostat that has that function. This setup won’t help with that.

The reason for this is simple…

These humidistats just open and close a switch and aren’t generally very accurate to boot. So the only reason to have one is so that the system will run based on humidity and NOT temperature during periods the customer is away.

This is why it is common to see these in second homes of snowbirds in Florida or people who travel a lot. The thinking is when you are away, you care about the humidity in the house and not the temperature which has a measure of truth to it… but often these controls cause more heartache than anything else due to common misunderstandings.

The Popular H46C1166

The most significant cause of misunderstanding is that they can be wired in two different ways:

  1. Open to prevent the system from running (Most common)
  2. Close to make the system run

Let’s look at each method and how to wire them and set them.


Open to prevent the system from running (Series)

The H46C is pretty simple in that it opens and closes at around the set humidity and only has two connections. In this strategy, you break the Y wire leaving the thermostat or the R wire entering the thermostat with the humidistat. This way, it shuts the system down when the humidity in the space is lower than the setting. If you break Y, the blower may still run continuously when the humidistat is open; if you break R, then the thermostat may go blank, or the batteries may eventually die.

If you wire it this way:

  • Set the humidistat to ON when the home is occupied
  • Set the humidistat to 55 – 60% when away
  • Set the thermostat to 75° – 80° when away

This way, the system will only run when the humidity is above the humidity setpoint, and the temperature is above the temperature setpoint. So a “safer” setting would be 75° with 55%, and a riskier but more energy-efficient setting would be 80° at 60%

Close to Make the System Run (Parallel)

This method works on the idea of setting the thermostat on a high setting when you are away and allowing the dehumidistat to turn the system on and off in cooling mode.

As shown above, this method connects between Y and R on the thermostat in parallel with the thermostat control.

First off, this strategy doesn’t work well on heat pumps though you could do it by adding a relay, and I’ve seen people wire it O to Y which really won’t work right in the heating mode because it will keep the system locked in cool by back-feeding O from Y.

So to be clear… I don’t like this way at all, but if you do wire it this way;

  • Set the humidistat to OFF when the home is occupied
  • Set the humidistat to 55% – 60% when away
  • Set the thermostat to 80° – 85° when away

So there you have it – If you want humidity control while occupied get a thermostat and system that have the ability to control airflow and runtime based on humidity as a factor.

If you want the system to run primarily based on humidity during away periods this can be done as shown above.

— Bryan


We can all agree that the future we all would have expected for 2020 when we rang in the new year isn’t the one we got. We are all worried and looking to hedge our bets or cut our losses in one way or another and that makes sense. Given what we now know let’s take a look at a brighter future and imagine what that might look like if we start making moves toward it.

Interest In “Essential” Jobs 

I understand that for the moment during “stay at home” even our industry is seeing layoffs, but for us that won’t last long.

The reality is that once this all settles down there will be a lot of people who want to work in jobs that aren’t as impacted by economic swings. While there will still be a huge shortage of skilled workers in the trade we will have an opportunity to bring in some new people to the trade who will value the piece of mind it can bring.


Rise of Practical Product Performance Testing 

When we have big problems people tend to come together to find real, practical solutions. I hope to see more of this lead to better testing standards for IAQ products so that we can compare them head to head and make the best choices.

In this test of a DIY filter from Smart Air Filters, they show the DATA of how well a DIY filter can do in reducing very small particles from indoor air. In our podcast with Founder Thomas Talhelm, we talk about how getting better data and interpreting it in clear and honest ways may be the future of the IAQ industry and that’s a future I can get behind.

Apprenticeship Revolution

Registered apprenticeship programs are a really nice alternative to college where students can learn as they are employed with participating employers. Many people will have a desire to get out of debt and stay out debt while they pay their bills from their own efforts. I look forward to the future where more companies participate and more high-quality techs spend time teaching in the field and in classroom settings.

Cut Through Red Tape

We’ve already seen many building departments going to remote video inspections and many previously “essential” processes going to the side to keep the world running. While some of this isn’t always the best, I hope some of the best parts remain and video inspection seems like a really good idea to save time and labor and dare I say pollution? (less driving around and return trips).

More Technology Solutions

How many people have and will use ZOOM for meetings, online learning for classes and online signature capture for forms and documents? Necessity is forcing us to adapt and learn new things. Even NATE and RSES are embracing online accredited classes and remote proctoring for exams which will be HUGE in helping busy people.

Disruptive Innovation 

When the going get’s tough we often rethink the way things are done. I talked with Michael Housh and Jim Bergmann about some of the problems we could solve with a self-contained, R-290 heat recovery chiller in residences. Far fetched? maybe… but big ideas can lead to practical steps of growth and that always excites me.


Return to Fundamental Business  

What are some good fundamentals to follow? You already know them but let’s do this anyway.

  • Don’t go into debt
  • Only spend money you have
  • Make due with what you have and save your money to grow
  • Hire good people and train them for the skills
  • Fire people who don’t do their job well or exhibit toxic behaviors and do itquickly
  • Price your services wisely so you make a 6% + net profit
  • Don’t confuse markup with gross margin
  • Keep track of ALL your expenses
  • Bill immediately and follow up on accounts receivable weekly
  • Watch your cash
  • Learn to read your P&L and Balance sheet (Basically follow Ruth King)

Are we being idealistic? Certainly.

Will most of these happen the way we hope? Probably not.

But if we have learned anything we have learned over and over that steps towards progress have setbacks and unexpected discoveries that can sometimes lead to greater progress than we could have expected.

— Bryan


As HVAC contractors, we are tasked with keeping staff and customers safe during the outbreak, and we are relied upon to provide some guidance to customers about how to protect themselves against the virus in the air.

For employers and employees looking to navigate the new FMLA / FFRCA legislation, we put together a document that covers the main points, and we included the federal poster on the topic HERE

At HVAC School, we’ve been doing a lot of reading and listening to people with a lot more knowledge on these topics than we had before writing this guide. Even after all the best research we can muster, it must be said we are not microbiologists, epidemiologists or industrial hygienists. Our understanding of this outbreak is ever-evolving, and we will update this guide as new information becomes available, but the best resource for general information regarding prevention and care is available at the CDC website.

Other important industry resources:


EPA Biological Pollutants’ Impact on Indoor Air Quality

EPA Green Cleaning and Sanitizing Guide

Latest COVID 19 projections in the US and by State

Virus Basics

As with many things in our trade, it is helpful to gain a simple mental picture of how things work, even if it isn’t a perfect representation.

The virus isn’t “alive” in the way that fungus or bacteria is alive. It is a spiky sphere that contains genetic information (in the case of SARS-CoV-2 it is all RNA) that causes the host cells to “make” more of the virus.

When we ingest or inhale the SARS-CoV-2 virus, it attaches itself to our cells and “injects” that genetic information into our cells, causing them to create more of the virus to infect more cells with new spiky spheres. Some of these get expelled from our mouth and nose when we cough, sneeze, or talk, and some emissions make their way onto our hands when we touch things.

The key thing to get our heads around:

The virus spreads outside of us, but it only REPLICATES inside of us

We are the virus factories, our own cells make it based on the tiny plans planted in them. This matters, because if we think of viruses like bacteria or fungus that are living and grow, then we will come to incorrect conclusions.

Viruses have a fatty (lipid) coating that makes up the sphere, and the spikes that make it stick are little proteins.

When the fatty layer of protection is broken, the genetic information inside the virus can no longer get into your cells, rendering it non-infectious. In fact, when we say that something “kills” a virus that is what we are really saying, because it wasn’t alive to start with.

One big factor in infection is the immune function of the person who gets the virus. If someone has immunity, it means that their immune system has identified the virus as a risk due to current or previous experience, and the body sends antibodies to surround and neutralize the virus.

A vaccine is generally a weakened or deactivated version of a virus. Vaccines are injected into a person so their immune system can “learn” to fight the virus before an actual infection occurs.

As professionals that interface with consumer health, it must be our mission to help provide an indoor atmosphere that promotes immune function, as well as protects against contaminants.

This means we must seek not only to neutralize viruses, but look to contribute to all the factors that can create and maintain a healthier indoor environment. This includes:

  • Good air ventilation and circulation to reduce airborne chemicals (VOCs) and CO2
  • Humidity control
  • Temperature control
  • Air filtration
  • Carbon Monoxide Monitoring and testing to keep it as close to zero as we can
  • Control over duct and building envelope leakage to keep control over indoor air factors and quality

This webinar video from Nate Adams and Retrotec is an excellent source of detailed information, and is also one of the resources I used heavily in writing this.

Use Soap / Detergents

The reason soap works well to deactivate the virus is the nature of the bonds that form on the fatty lipid shell on the virus. The soap breaks the lipid shell apart when hands are washed with enough time and friction. The “antibacterial” properties of some soaps are just that, antibacterial which means they work against bacteria, not viruses.

The difference between a soap and a detergent is soap is natural and made from animal and plant sources, and detergents are synthetic and are generally specifically designed to overcome some technical challenges with soaps.

A molecular biologist I spoke to summed it up this way:

“Basically, if it makes suds, it’s doing what you need”

Obviously, the effectiveness of any cleaning process depends on many things like the amount of soap used, dwell time, and friction

This isn’t to say that using an anti-viral disinfectant AFTER cleaning is a bad idea. Some surfaces can be tough to reliably clean with soap and disinfectants can also disrupt and deactivate the viral membrane. Make sure to use an EPA LISTED DISINFECTANT that is also specifically listed and labeled for HVAC use.

There is evidence that high-temperature steam is also effective as a sanitizer. This is a quote from the EPA Green Cleaning and Disinfection Guide:

“Dry vapor steam cleaners have been shown to be very effective for disinfecting and is approved for food contact surfaces as well as other surfaces.”

As always, we strike a balance between safety and effectiveness, and look to use products that are effective and safe when neutralizing viruses. We need to consider the technician and the occupants in our decision making.

How Do We “Catch” (become infected with) a Virus?

There are several different ways that a virus is transmitted, but the Coronavirus (SARS-CoV-2) is transmitted primarily in two ways:

  1. Bio-aerosols: Basically viruses contained in our saliva that come from our coughs, sneezes, and breath, which appear to make up the majority of the risk.
  2. Surface contamination: Occurs when someone gets viruses on their hands and then touches a surface; then someone else comes along and touches that same surface. Surfaces can also become contaminated when bio-aerosols fall and settle on surfaces.

The virus survives best inside our bodies, and once it leaves, the clock starts ticking for how long it survives before it becomes deactivated and non-infectious.

Again, the virus doesn’t “grow” outside of us, it just spreads out, and some other unlucky person can either breathe it in, or pick it up from surfaces, and then transfer it to their face from their hands.

This is why hand-washing, disposable gloves (regularly changed), and masks are effective at preventing the spread. In the USA we have not widely used respirator masks such as the N95, primarily because they are cumbersome and uncomfortable to wear all the time and, most of all, because there is a shortage for healthcare workers.

Wearing surgical masks may not effectively protect the wearer but can assist in containing the bio-aerosols in the mask preventing others from being infected by the wearer. This is somewhat disputed by well-researched sources, like this one, with the conclusion being that almost any mask is better than no mask.

Either way, we know that quality masks like N95 are a best bet, but we need to save them for healthcare workers at this time.

If you are using masks there is a lot of discussions as to how to sanitize them without disposing of them when there is short supply. This research cited by Stanford seems to show that 30-min in a 156°f oven is one of the better options.

HOWEVER… the report is careful to state that there are many factors to sanitize masks and they STRONGLY ADVISE AGAINST sanitizing at home In a home oven.

Health care workers are at a much higher risk of contracting the virus, due to procedures such as intubation, which is why respirators are a necessity for them, and not necessarily for other workers outside of healthcare like HVAC techs.

Viruses are small… much smaller than dust, pollen, dander, bacteria and fungus. This means they may remain suspended in the air given the right conditions, and are hard to catch in typical air filters. But it isn’t as bleak as it may seem.

This article from Smart Air covers why many high MERV filters can still help significantly with viruses, even if the “holes” in the filter are larger than the size of the virus.

Obviously, HEPA filtration is still the gold standard for the capture of tiny particles, but even HEPA captures really tiny particles via a phenomenon called diffusion.

There are many papers and a lot of back-and-forth on how long the virus can survive in the air, and on various surfaces. The answer is, there is still a lot we don’t know; but we do know that it can survive in the air, but it appears unlikely that an infectious dose will travel all the way into the HVAC equipment and survive long enough to be a risk to HVAC professionals. This doesn’t mean we shouldn’t take precautions, such as wearing gloves, bagging filters, and even wearing masks while removing filters, but the risks do appear to be low even in worst-case scenarios like medical HVAC applications.

We know for sure the virus lasts longer on stainless steel and plastic than it does on copper… So is it time to go back to copper door knobs and handrails?


Our greatest risk by far… is still when we are around people who carry the virus


So to summarize some virus basics:

  • Viruses aren’t alive in the same way as bacteria and fungus
  • People carry the virus, and in people is where it replicates and spreads not on surfaces
  • Viruses are tiny and hard to catch when compared to most other particulates 
  • Soap and detergent cleaners works well on viruses
  • Sanitizing with appropriately tested and rated sanitizers is still a good idea
  • Good masks do help, but medical professionals need them most

Protecting Workers and Customers

For an HVAC contractor, it is in our best interest as an “essential service provider” to keep our technicians and customers safe while still doing our jobs. The following is a list of policies and procedures you could put into place to help.

Standard Practices

  • Wash hands thoroughly for 20 seconds with soap and water using vigorous friction 
    • Before Eating
    • After Each Call 
    • After Bathroom Breaks
    • After Fueling Vehicle
  • Employees stay home if they showing any symptoms, make it easy on them to stay home.
  • Check temperature every morning before the start of work and stay home if it exceeds 100.4° F
  • Practice social distancing of 6’ – no shaking hands
  • Don’t touch the face
  • Sanitize tools, steering wheel, and cell phone with 70/30 isopropyl alcohol or other approved sanitizer (Don’t mix products)
  • Avoid ride-alongs where possible

Customer Interaction Zones

  • Ask customers if any occupants have symptoms before dispatching. If so, limit to only necessary calls, wear a respirator in the customer interaction zones (when available), and request the customer to wear a surgical mask. 
  • Request all customers to pre-open doors for the technician (where possible), to limit surface contact and to maintain 6’ of distance
  • Wear disposable gloves and safety glasses while in the customer work area when handling knobs and surfaces in the customer zone (N95 masks once there is no longer a shortage) 
  • Wear work-appropriate gloves while performing work tasks
  • Sanitize knobs and other common touch areas at the end of the work

Servicing Equipment 

  • When servicing equipment, use usual PPE of gloves, safety glasses or goggles as appropriate for the task, and standard PPE masks/respirators when changing filters or working with chemicals. 
  • Service filters and evaporators with the blower off
  • Use only approved cleaning and disinfection products, and follow the specific direction for use for HVAC equipment on coils, blowers, and air filters. 
  • Washing then sanitizing evaporator coils, blower wheels, and cabinets with approved cleaners and processes is always a good idea anyway. 

Remember – the greatest risk of infection if when you are in proximity to other people, not in the equipment itself.

Improving Customer Outcomes

Another thing our customers look to us for is ways to help protect themselves and their families from infection. Along the way we need to make sure we:

  1. Do no harm
  2. Tell the truth
  3. Provide solutions that represent a value
  4. Execute the solutions properly

This is surprisingly hard in the case of this virus because it isn’t living and it propagates inside people, not on surfaces or in equipment.


  • More indoor time by occupants means more indoor pollution and exposure
  • Maintaining healthy indoor conditions improves immune and respiratory function  (,,
  • More surface sanitizing means more chemical use indoors and more ventilation and dilution needs
  • Filtration is required for particles such as dander, dust mites, and pollen. Dilution is required for VOCs and CO2 
  • CO monitoring is a must for buildings with any fuel-burning appliances, due to the impacts on pulmonary function of even low levels of CO. 


There are many different ways to bring in outdoor air. As we ventilate, we need to filter, and control the humidity of that air if it is too humid, too dry, or full of particulate matter. It helps to dilute indoor contaminants with outdoor air so long as we:

  • Provide filtered, humidity-controlled outdoor air according to ASHRAE 62.2 or similar (dehumidification or humidification may prove challenging at high ventilation rates)
  • Ventilate during occupancy or according to CO2 / VOC levels
  • C02 levels higher than 1000 PPM are attributed to decreased cognitive function and perception I love this guidance for a simple way to filter room air on a low budget from the Hayward Score


  • HEPA filtration where possible 
  • MERV 13+ is ideal with 4” or thicker media
  • Activated carbon/charcoal filters can help to reduce VOCs and O3 
  • Filter outdoor air independently / redundantly 
  • Ensure system static pressures are within design 
  • Counteract higher resistance air filtration with a greater surface area to reduce filter pressure drops

Humidity Control 

  • Humidity that is too low may make COVID-19 worse 
  • Humidity Control between 30 – 60% at all times is highly recommended with 30% being ideal for Winter in cold/dry climates, and 50% – 55% being ideal for Summer in warm/humid climates
  • Humidity control also impacts VOC off-gassing, bacteria, fungus and O3

Kaleb Saleeby wrote an excellent overview on these three factors HERE

Be Prudent Regarding IAQ Products

There are numerous IAQ products on the market with varying levels of effectiveness and safety. At HVAC School, we advocate for more independent testing under real-world conditions, testing against a wide range of particles, VOCs and biological contaminants. We also advocate for peer-reviewed studies of these independent tests. As it stands, products like direct air filtration are well established, whereas products that use active production of oxidizers have not been as well tested in a truly independent fashion.

Because of this, I suggest only selling IAQ products where:

  • You understand the underlying technology, not just the marketing or trade name
  • You have sought out the best independent studies you can find
  • You have a grasp on all of the risks (all products have risks)
  • You ensure the products are installed properly
  • The customer has been communicated with based on the science and real research
  • You can monitor the IAQ characteristics with a quality monitor BEFORE and AFTER

Avoid falling for:

  • The idea that any core IAQ technology on the market is proprietary
  • Claims of kill rates or capture rates without the specific test criteria
  • Claims that things are “NASA technology” or “Space approved” etc.. without understanding what that means


Risks to Watch For 

Every IAQ product has some risk factors, even if they are minor. For example, putting in a better air filter (from a MERV standpoint) can restrict airflow, bringing in more outdoor air could increase or decrease humidity beyond the safe range etc…

Even some of our favorite IAQ solutions can cause problems if we don’t plan for them and think them through. Here are some common things to watch for in common “boxed” purification solutions:

  • Products that produce O3 
  • UV
    • UV has been shown effective in irradiating metal surfaces in close proximity (
    • Any UV light that shines on a surface that is not metal where VOCs can be produced 
    • UV lights and eyesight 
  • Oxidizing air purification 
    • Incomplete degradation
    • Impacts of ions directly on respiratory function 
    • Efficacy in large areas / high-velocity air streams 

The following are some great videos to watch to understand more about these topics

(Employees) What to do if you are sick?   

  • Follow the CDC Guidelines
  • Stay Home, Stay Home, Stay Home
  • Call your healthcare provider or visit an on-line clinic.  Follow their instructions.
  • Do not go to the doctor (clinic, urgent care, or ER) if your symptoms are mild.  
  • Call 911 if your symptoms are life-threatening.

(Managers and Owners) What to do right now

  • Follow CDC’s guidelines to create an “Infectious Disease Outbreak Response Plan” for your place of business.
  • Do employees all know who to contact if they’re sick?
  • Who will do the cleaning procedure?
  • Who is responsible for the risk assessment?
  • Who decides if the business will shut down?  And Open back up? How will you notify everyone?
  • Do you need to notify customers?

(Managers and Owners) What to do in your place of business if an employee is sick or “presumed COVID-19 positive”

  • Follow CDC’s instructions for “Disinfecting Your Facility if Someone is Sick” 
  • General information (as of 21-Mar-2020): Most places in the US are not able to test everyone who has the symptoms of COVID-19.  Therefore, it is most likely that if an employee becomes sick with COVID-19 symptoms, you will not have test results to confirm if they are positive or negative.  Most likely, they will be evaluated and if their symptoms are close, they will be given instructions to act as if they are COVID-19 positive. They will be “presumed COVID-19 positive”.

(Managers and Owners) What to do if an employee has had contact with or lives with someone who is sick or “presumed COVID-19 positive”

Contacts of Asymptomatic People Exposed to COVID-19: CDC does not recommend testing, symptom monitoring, or special management for people exposed to asymptomatic people with potential exposures to SARS-CoV-2 (i.e. in a household). People who have been exposed to “contacts of contacts” are not considered exposed to SARS-CoV-2.

In closing, this guide is written to help contractors and technicians work more safely and keep customers safe. It is not the final word on any of these topics, and should not be used without FIRST reading current CDC and OSHA guidelines as well as consulting an experienced industrial hygienist.

— Bryan

Some More Excellent Resources 

Healthy Indoors Magazine COVID Webinar Series

Find out more about the health or your home environment with the Hayward Score

I wrote this years ago, but now this feels like a season of tough decisions. I hope this helps.

When you run a small business you are called upon to make hundreds of decisions both large and small, but sometimes there comes a tough decision you REALLY don’t want to make. It’s times like these that you could use an article and some long, complicated initials to help you get up the guts to make a decision… and this is THAT ARTICLE. 


Do a Pre-Postmortem 

We call this performing a PPM (Nobody calls it that) 

If you are a leader who can make knee jerk decisions based on emotion or a “whim” you may consider this technique to help with some perspective. 

A post mortem is looking back at something that went wrong and figuring out what caused it. A pre-postmortem is attempting to look at the choice you have now and diagnose it with a future perspective to see what could go wrong. 

Try to separate from the here and now and put yourself in the mindset of yourself 6 months, a year, even 5 years from now. Now think about how the future “you” will look at the decision you are about to make (or fail to make) and what the potential ramifications will be. 

Sometimes a tough problem becomes more clear when you can look back at it with future eyes. 


What if You Couldn’t Fail? 

You walk into the boardroom, and nail your presentation to the chairman of your largest customer. He looks over his glasses and asks, “Have you done a WIYCF analysis on this?”   

This is the opposite side of the spectrum from the PPM, if you are a leader who often lacks confidence or clarity or can be overwhelmed by fears, it may be helpful to think about what choice you would make if success was inevitable, what if you LITERALLY COULD NOT FAIL?

If you have ever met a leader who is abounding with confidence, it is often that they don’t consider the possibility of failure. This isn’t to say that they don’t fail…they just don’t acknowledge it when it happens and don’t let their mistakes reduce their confidence or forward momentum. When you make decisions from a “can’t fail” mindset you will often find a way to make the impossible possible. If you find yourself inhibited by fear, doubt and second-guessing you may want to focus on the WIYCF report. Heck, you may even become a reality TV star or President.


What Would Your Grandma Do? 

I often think of the wisdom of my Grandma Betty. She has lived well through getting married young, running a business, dealing with my Grandpa’s wild schemes, raising children and seeing countless cultural changes and wars come and go. While she may have no specific domain knowledge of my business, she has a good perspective on life in general. 

Often when I think about what she would do I am reminded that nothing is as horrible as it seems in the moment, and that a little patience and kindness goes a long way in solving life’s problems. What would your Grandma advise in this decision?


Who Wins? Who Loses?

When making a hard decision think about who the winners and losers are based on each option. I think about the three legs of the company stool as: profitability, employee morale, and customer satisfaction. Every decision I make has to take all three of these into account as well as benefit at least two of the three. 

Step back and think about how to make it a…wait for it …business cliche coming…a

“Win-win situation” 


Which Choice is Simpler?

Choose the simpler one. No initials required.  


Which Option Makes the Most People Smile For The Longest Period of Time?

Let’s ruin this concept by making up a corporate term for it. We will call it the “Time Average Mouth Corner Lift Factor” of TAMCLF.  

Business isn’t just about the numbers or the money, it really is about people and building relationships. Think about the choices you have to make and imagine the people who are most important to your business. Imagine the faces of your employees, partners, customers and your spouse and children. Are they smiling, or frowning? Will they be smiling or frowning a year from now once the decision has a chance to run its course?

This does not mean that business is a democracy or a popularity contest. Sometimes you will make decisions and other people will not like them, but it is still a HUMAN process that affects other HUMANS. 

When making a hard decision it is best to skim through, gather good advice, give yourself a deadline, seek simplicity and then MAKE THE DECISION. 

It only gets worse when you procrastinate. We call this the “Things Going Bad When You Procrastinate Coefficient” or TGBWYPC.   

 — Bryan

This is a recent call I ran that clearly had an interesting past. It had a condensate pump to pump the water just a few feet up to a drain that went to a common drain. The “cleanout” after the trap is supposed to be a vent, not a cleanout, which means it needs to be uncapped and vented higher than the indoor drain pan so that if the drain backs up the water goes back into the system and trips the condensate switch.  With the current position, the vent could not be raised because it would come right up in front of the filter.

My best guess is that when the installing contractor installed a new, larger air handler it no longer had the fall they needed to get the existing drain so they capped the vent (seen in the photo above before it goes into the wall).

I’m using this system as an example because it has every possible drain don’t you could come up with

  • No Cleanout
  • No float switch (condensate switch) to prevent pan overflow
  • Vent Improperly placed or causing filter obstruction
  • Using a pump when one wasn’t originally needed
  • Using a common drain with no vent
  • No insulation on the condensate drain horizontal runs

We did rectify as much of it as we could here which included

  • Adding a condensate switch
  • Repiping with a proper cleanout and vent before the pump
  • Insulating the horizontal portions

Unfortunately, we couldn’t eliminate the pump and I forgot to take “after” photos

This is an example of a drain properly pitched, insulated, trapped and vented with a system and secondary pan switch installed. Two things I do notice on this one is the pan doesn’t look like it overlaps 3″ at the top of the unit, The cleanout would be better right above the trap and I can’t tell what’s supporting this drain to ensure the pitch stays correct.

It’s amazing how much there is to the simple, humble condensate drain.

— Bryan

Let’s Start with the basics.

Water freezes at 32° Fahrenheit and 0° Celsius at sea level and atmospheric pressure. When any surface is below that temperature, and the air around it contains moisture, ice/frost will begin to form. In some situations, ice is to be expected, such as in refrigeration evaporators and exposed portions of the refrigeration suction line and the metering device outlet in refrigeration applications. Frost and freezing are also likely in heat pumps operating in heat mode. The outdoor coil on a heat pump becomes the evaporator coil, and during low outdoor ambient conditions, it is expected that the outdoor coil will eventually freeze and require defrost.

The reason that frost/ice is inevitable in some applications is just due to the laws of thermodynamics (moving heat). To get heat from one place to another you need to have a difference in temperature. So inside of a freezer where you hope to get the box temperature to 0°F  the coil temperature needs to be BELOW 0° to transfer heat out of the freezer and into the coil and then down the suction line to the compressor. If you have a freezer with a design coil temperature difference of 10° and a design superheat of 8° the coil will be at -10°F and the suction temperature at the evaporator outlet will be -2°F.

On a heat pump running in heat mode, you will commonly find an evaporator (outdoor coil) that runs 20° – 30° colder than the outdoor temperature. This means that if it is 30° outside the outdoor coil temperature could easily be 0°F. In these cases, ice is normal and periodic defrost is expected and required.

Some systems we work on and install will freeze. Air conditioning is not one of them.

In an air conditioning system, we must keep the evaporator temperature above 32°F. We can easily know the evaporator temperature by looking at our suction saturation temperature (suction gauge temperature for the particular refrigerant). For R22 32° is 57.73 PSIG at sea level, R410a is 101.58 PSIG, and R407C is 67.80 PSIG.  If we don’t keep our evaporator coils above these coil pressures/temperatures, the system will freeze. The rate at which it will freeze is a function of –

  • Time – The longer it runs at or below 32°, the more frost/ice will build
  • Moisture – The more humidity the air contains as it passes over the coil
  • Temperature Difference – The colder the coil, the faster ice will build
  • Air Velocity / Dwell Time – The faster the air moves over the coil, the slower ice will build, the slower it moves, the quicker it will build
  • Coil Design – Closer fins will freeze faster

The ice buildup always starts in the evaporator and works it’s way outside. If you have a frozen compressor, you have a frozen evaporator. When you find a frozen system, take your time and get it fully defrosted. Take care to manage the ice melt water and keep it away from motors and boards where it can cause damage and a shock hazard. Some towels and a shopvac are great to have handy when defrosting a unit. When possible allow it to defrost slowly and naturally to prevent damage.

So what circumstances can result in low coil temperature?

Low Evaporator Load 

Low load is often equated with low airflow… and it usually is low airflow, but there is a bit more to the story than that.

An air conditioning system has one final design result, one big end goal that we are shooting for. Matching the refrigeration effect to the evaporator load.

We must match the quantity of refrigerant moving through the evaporator coil to the amount of heat the evaporator coil is absorbing

That is our mission, and that is the primary reason we measure superheat. Superheat gives us a look at how well we are matching refrigerant flow to heat load. High superheat means evaporator underfeeding; low superheat means overfeeding.

There is an issue though, we could have a correct superheat and still have a coil temperature of under 32°, and this is not acceptable in an air conditioning system. When the coil absorbs less heat than designed the coil temperature and suction pressure drop. In cases where a TXV or EEV is controlling suction superheat the suction pressure will drop even further as the valve attempts to keep the superheat from plummeting.

This is why we must size a system, and it’s ductwork appropriately for one another as well as for the space, climate, and even altitude. If we install a system that requires 1200 CFM of airflow to properly balance the refrigeration effect to the load at 75° design indoor temperature and that system is only receiving 900 CFM of airflow, you run an excellent likelihood of freezing. This is especially true when the outdoor temperature drops or the customer decides to drop the thermostat lower than usual.

Low load is often due to low airflow, low indoor ambient conditions and equipment oversizing. Low load conditions will have symptoms of low suction pressure, low superheat, low head and high evaporator Delta T. Start by looking for the obvious, dirty coils, dirty filters, dirty blower wheels, blocked returns, mismatched equipment, improper blower settings, closed registers and undersized ducts. You can then move on to performing static pressure tests to locate more difficult issues.

Low load is the most common cause of persistent freezing and should be top of mind when a technician is diagnosing a freezing system

Low Refrigerant In the Evaporator

System undercharge or underfeeding due to restricted refrigerant flow (restricted filter driers, plugged screens, failed expansion valves or undersized pistons) can also result in freezing over time. Low refrigerant can result in fewer molecules of refrigerant in the evaporator coil which results in lower coil pressure because the coil contains both saturated liquid at the beginning of the coil as well as superheated vapor towards the end. This type of freezing requires time because less refrigerant in the coil equals less refrigeration (cooling) effect.

If the coil temperature is below 32° in an undercharged situation, the coil will simultaneously build frost as the beginning of the coil after the metering device AND underfeed the coil resulting in high superheat. Over time as the frost builds it will start to block the opening of the coil which blocks airflow and insulates that portion of the coil from airflow which reduces the coil load. Eventually, once the coil is blocked with frost almost all of the load is removed from the coil and you have a low refrigerant issue that LED to a low load issue that resulted in a complete freeze up.

Once you defrost the system and test you will find that low refrigerant charge conditions result in low suction, low subcool, high superheat and low head pressure. Refrigerant restrictions will be low suction; high superheat, high subcooling.

Often once you resolve the charge issue, you may also find another low load issue as well that contributed to the freezing. In many cases when low charge is the cause, the customer will notice the issue before the system is FROZEN SOLID.

Low refrigerant will often result in a partially frozen coil more than a full block of ice. Remember, low COIL refrigerant can be restriction related or low charge, but if it’s low charge you will have low subcooling if it is restriction it will have high subcooling.

Low Outdoor Ambient

When a cooling system is operated during low outdoor temperatures the condensing temperature and head pressure will drop. If the head pressure drops low enough the suction pressure will also drop resulting in freezing. The only way to resolve this cause is to install some type of head pressure control such as fan cycling or fan speed control to keep the head pressure from dropping significantly.

Blower Issues

If the indoor blower shuts off, the coil temperature will drop. Sometimes a blower motor will have internal issues or controls issues that cause it to shut off periodically. This can cause intermittent freezing that can be hard to diagnose. Checking controls, belts, blower amperage, bearings, and motor temperature can all help in diagnosing these issues. Sometimes leaving an amperage data logger on the motor along with a coil or supply air temperature sensor can give you the ammunition you need to pinpoint an intermittent issue.

When diagnosing a freezing situation don’t jump to conclusions, get all the ice defrosted before making a diagnosis and keep a sharp eye out for airflow and design issues. Freezing is often due to more than one issue combined that act to turn your customer’s air conditioner into an ice machine.

— Bryan


I ran a service call today with another tech where the previous tech had diagnosed an intermittent piston restriction. I read the history beforehand and for the past several years there were a lot of assorted comfort complaints and lot of little charge adjustments in both the Summer and winter, it is worth noting here the system, like many in our market this system a heat pump.

There were mentions of freeze-up during the Summer and high pressure cut out during the Winter which had me thinking airflow even before we arrived.

As we pulled up I noticed it was a townhome community with four homes per building.

There was no tenant home so we accessed the home via lockbox and as we walked up the stairs I was noticing the home was quite small… two bedrooms and two baths and when we opened the air handler closet it was….. 3.5 tons

The place had 12″x12″ tiles on the floor and it was a simple rectangle so we counted up length x width and the entire home was just under 1200 sqft.

Now sqft per ton is no way to do a load calculation… I admit it

But this townhome had occupied spaces on both sides meaning the only exposures and windows were on two sides with big trees shading the back, the building was built in 2007 and this system was installed in 2016.

What’s the next move you would make?

Common Sense

The great thing about having 4 other, almost identical units on the building is that we can easily see what tonnage they had installed, and they were 2-ton units…. makes more sense.

So in 2016 some fly-by-night company hacked in a 3.5-ton unit rather than using a 2-ton that may have been a little oversized to begin with given the low loads on this home.

The result is a system that is running REALLY low airflow resulting in low evap temperature and low superheat in the summer and high head pressure in the winter. Techs had been trying to “fix” the problem each year with little charge adjustments rather than finding and fixing the underlying issue.

After walking around the home we found some vents closed… likely because they were blowing somebody’s wig off with the high air velocity.

We went in the attic and found some ducts unsealed, some insulation pushed out of the way and two bath fans venting freely in the attic.

None of this required fancy tools or advanced diagnostic techniques to diagnose… just some common sense… some looking around and a little comparison to figure out the story.

Elementary my dear Watson… Elementary

— Bryan

I’ve always opposed the practice of grabbing a hub puller as the first method of removing a blower. This video by Brad Hicks with HVAC in SC on YouTube demonstrates the exact method I use to safely remove a blower wheel without damaging anything. Thanks Brad!



This is going to be on removing blower wheels from blower motors I see a lot of guys that will just get a fancy puller they won’t do any prep work on the motor shaft they’ll just drop their puller on there and try to remove it. Sometimes it works sometimes it gets everything bound up to where you have to replace the blower wheel.
Basically, what I do is just loosen the set screw,  you can see how rusty this one is right here but loosen the setscrew and force the wheel on the hub down farther first.  You can see now we have some clean metal and then I just take a couple minutes to just with a piece of Emery cloth or sandpaper just clean this shaft up really really good. Take a couple extra minutes to prep that shaft once that’s nice and clean you just grab something some sort of lubricant rust breaker wd-40 in this case spray a little bit on there and nine times out of ten this wheel will come right off no problems at all without any puller. I do hope that helps thanks for watching.
— Brad

When working in a business with people, you have two options:

1. Become bitter as you experience people and life and issues
2. Grow from experiencing people and life and issues.


I’m not proud to say it, but I realize now that when I started my business and had bad experiences, I would run to option #1. and start building a wall between people and myself. Every difficult situation would bring me to my wall and I’d add another row of bricks.

It happens. We get taken advantage of, our expectations are completely dashed and unmet, we lose money, our ego is crushed, etc.

Often times money was never the issue for me, but it was more a matter of emotional heartache and inconvenience. 

A quick example: In the early stages of starting our family business I had a commercial customer where I was installing air conditioners within cell phone tower equipment rooms. Every job made money, but frustration would build with last minute changes on their part. We’d make special trips to get different supplies to help meet their demands, and I sensed in myself that I was building my wall higher and having thoughts like: “I will not work with these types of jobs in the future”

I see now that I was putting an emotional limit on myself and was simply-unwilling to grow.

Instead of focusing on the fact that I had an opportunity to expand and broaden both my experience and customer base, I was shrinking my horizon by committing to only approach things that I was comfortable with and things that I naturally enjoyed doing.

While I didn’t give up entirely on insane projects, I would often be heard saying to a customer, “We aren’t taking on that type of project at this time” or to the office personnel I’d say, “Nope, I’m not going to deal with the difficulty of that type of customer.”

Somehow I felt as if I was being a strong leader by being willing to “Just say no.” 

I was fooling myself. Instead of allowing circumstances to be an opportunity to grow, I was allowing circumstances to control my behavior.

What changed for me was coming to realize that I spent too much time judging motives and allowing the behavior of others to affect how I looked at my business and purpose.

As time passed I came to see that I could keep on the way I was going, but I wanted more. I wanted to expand myself, I wanted to see that others’ crazy wasn’t so terrible after all. In fact, I too have a form of crazy; it just looks different than someone else’s.

Why not choose to work together and support one another instead of creating walls of indifference? Find enough common ground to make it a win/win situation.

While I would still say there are times to say “no” to a job or a potential customer, it’s based off of different reasons than what I had before. It might be “No, I can’t make money on this job,” or “My employees just don’t have the skills and/or equipment to handle this problem,” or “The scope of work is way too vague for me to bid on this,” instead of the old “This is new and unfamiliar. I’m not doing this!”

In summary:

  • Find opportunities in difficulties
  • Shed fears and embrace new things
  • Find common ground with others and don’t judge their motives
  • People are crazy, and so are you
  • Valuing others will genuinely grow you as an individual, and as a business

What is an experience where you’ve had to deal with heartache, but can still see it as an area of growth?



At the time of the publication of this article, COVID-19 (coronavirus) is spreading across the world at an alarming rate, and many people have self-quarantined to help slow and/or stop the spread of the virus. These precautionary measures are prudent and responsible. However, with the increased amount of time people will now spend inside their homes, there is a hidden factor to be aware of, which many people won’t think about. The prolonged occupancy of homes with increased cooking, bathing, and cleaning time will significantly impact the indoor air/environmental quality of these homes. An issue like this may not be measurable, but it is inevitable. In a time when many technicians, companies, and manufacturers will use this health crisis as a way to promote the sale of IAQ products in ways that can only be judged as unethical, it is imperative to the honest and curious technician to understand how to do her part in educating customers, and keeping everyone healthy.

This article will stay away from talking about specific types of boxed devices out there that “purify” the air, because that’s a topic for another day. The focus here is on the three main processes available to technicians and homeowners to improve indoor environmental conditions. Taking these one by one, technicians should have a thorough crash-course understanding of each and its importance to indoor air quality (IAQ). Ventilation, Filtration, and Humidity Control.

The first step in understanding a healthy indoor environment is to recognize the villains one must fight against in order to keep an environment healthy. Particulate Matter (PM), Volatile Organic Compounds (VOCs), Humidity (high or low), Carbon Monoxide (CO), Carbon Dioxide (CO2), Ozone (O3), etc. are just a few. These are the elements that tend to concentrate themselves in tight indoor environments. Each of the “Holy Trinity of IAQ” is designed to deal with these undesirables in their own dedicated way.

Everyone should know what a bath fan is. If you don’t have a bath fan, you probably live in a house not updated since the 1970s, and you likely have other decor issues to deal with as well. Bath fans are the most common mechanical ventilation in homes today. They are a form of negative pressure ventilation. As the fan pulls air from the room and expels it (hopefully not in your attic), this creates a negative pressure on the building envelope, and air from outside is pulled in through the cracks and crevices around your windows, door frames, attics, and through Jerry’s mouse hole…which everyone has…right? This type of ventilation is by far one of the least desirable, because you exact zero control over the quality of air you are bringing into the home. The air could be high in humidity and temperature, or it could be passing through layers of blown-in insulation inside your attic; neither of which are ideal. Air from these places isn’t really fresh.

The general consensus is that positive or balanced pressure ventilation is best. Examples of positive pressure ventilation include Make-up air units (MAU), Dedicated Outdoor Air Systems (DOAS), and the use of a scuttle (a small duct run from outdoor air into the return ductwork for HVAC systems). Balanced pressure ventilation is accomplished through mechanical equipment like Energy Recovery Ventilators (ERV), Heat Recovery Ventilators (HRV), and Conditioning Energy Recovery Ventilators (CERV). Each of these technologies has their advantages and ideal applications. The reason positive/balanced ventilation is desirable is for its ability to control the fresh air. If you can control the air you breathe, you can keep it “fresh”. For all of these options, there are applications for which they can be used that actually improve upon the quality of the air entering the space. But why do we care about ventilation? What’s so important about it?

Houses used to be built loosely. This isn’t to say they were built poorly, but houses used to be loose enough to allow for tons of natural ventilation. The codes and standards have evolved, and we now construct assemblies more airtight than in the past. This is why the EPA has published that indoor environments are often 2-5 times higher concentrations of air pollutants than outdoor levels, and can reach upwards of 100 times worse! This is because as people bathe, clean, and cook, VOC concentrations, Particulate matter, and humidity levels increase dramatically. People thought bath fans were for bathroom odors, but really that’s just a nice side-effect. They are for removing water vapor during and after showers/baths. Ventilation is utilized to dilute VOCs, CO, CO2, and other chemicals in order to maintain a comfortable indoor environment. I know of people who grew up watching their mother open all the windows of the house for a couple hours a week in order to “flush” the house. Mechanical ventilation is just like that, except more controllable and technologically advanced.

Particulate Matter is another indoor environment characteristic, which can cause a variety of health concerns. Particulate matter is categorized by its size in diameter, which is measured in micrometers (or microns). A lot of buzz is generated around PM 2.5, which is particulate matter with a diameter of 2 and a half microns; that is due to PM 2.5’s ability to do major damage to the human respiratory system. To give you an idea of the size of PM 2.5, the EPA has published that PM 10 is considered inhalable. PM 2.5 is 75% smaller than that! This means PM 2.5 tends to stay in the air stream longer than larger, denser particles. However, PM 2.5 is not the smallest particulate matter that can potentially do harm. PM 1 and 0.5 are also in the air, and they can easily make their way to our lungs and bloodstream. In order to combat against these airborne particles, it is important to filter the air with a high-quality air filter. There are filters designed to trap PM 2.5 and smaller (MERV 11 up to HEPA), and they are a critical component to any air distribution system. The third edition (2018) of the EPA Technical Summary of Residential Air Cleaners states that a MERV 13 is recommended for every HVAC system, or as high a MERV rating as the system will allow. 

EPA Technical Summary: Residential Air Cleaners (2018)

It is important to note that Particulate Matter does not refer to just dust. Particulate matter can be made up of pollen, viruses, bacteria, fibers, fungal spores, vehicle exhaust, etc. This fact makes it clear that filtration is not only important for the HVAC system, but also for the incoming air to any mechanical ventilation system. Humans are constantly submerged in this fluid called air. We must give more thought to the quality of the air we breathe. 

The final head of our three-headed IAQ dragon is Humidity Control. This can refer to either high or low humidity levels. Either extreme is unhealthy and can create an environment prime for health risks. On one hand, high humidity can cause respiratory issues, encourage dust mite life, allow viruses and bacteria to increase, allow VOCs to become airborne, allow increased chemical reactions, and allow microbiological growth to take place. On the other hand, low humidity levels can also cause respiratory issues, irritate mucous membranes, allow viruses and bacteria to increase, and allow for the production of ozone. The happy medium is the generally accepted ideal humidity index, which falls between 35%-60% relative humidity.

In order to control humidity indoors, a technician must be aware of her climate zone, and whether she must work to increase or decrease humidity levels indoors in relation to outside levels. For arid climates, humidification is necessary, and options such as higher airflows and in-duct steam humidifiers are great solutions. For humid climates, running lower airflows and adding mechanical supplemental dehumidification is ideal. Some dehumidification systems allow for ventilation as an option, and they include a high MERV filter to cover all the bases. This option is an ideal solution for certain applications. Humidity must be controlled in an occupied space for that space to be comfortable. People are much more sensitive to humidity than temperature. 

Looking at these three paths to creating and maintaining healthy air inside a home, it is important to realize these are Indoor Air Quality solutions. To create and maintain a fully comfortable indoor environment, air leaks, insulation, and load matching are other issues that would need to be addressed. However, in addressing the current issues with air quality in homes, this “Holy Trinity” is all any technician needs to exert energy into in order to help keep occupant air clean. There is a mindset that humans are never more intimate with their surroundings than when they inhale the air into their bodies. Technicians must take action to educate consumers and recommend the most effective solutions for IAQ improvement. 

There are many companies and manufacturers using this health crisis to promote the sales of popular air “purifiers”, which use chemistry to “clean” the air in lieu of ventilation, humidity control, and filtration. The technology of these products will be discussed in a later article, but the most important take-away at this juncture is how important it is to maintain control over the humidity, the outdoor air coming into the space, and the concentration of particulate matter in the air stream. The methods of dealing with the issues mentioned in this article are the only methods that have been time and volume tested over decades, and they have standards in place to help ensure their effectiveness on IAQ. 

So what do technicians do right now? Many homeowners may not want to spend the money on advanced in-duct filtration, mechanical ventilation, and humidity control during this time of uncertainty. Joe Medosch from has shared a very ingenuitive and affordable solution for many people to effectively filter indoor air. 

This DIY method is a great way to help encourage homeowners to remain healthy as they spend more time inside their homes. This “box fan filter” may also make it more viable for sensitive people to open their windows and doors for longer periods of time during pollen season, as this enhances the circulation of air inside, and adds filtration throughout the home. Another recommendation for homeowners is to utilize the bath fans and kitchen exhausts as a way of ventilation. ALWAYS run a bath fan during bathing activity, and continue to run it 10-15 minutes afterward in order to prevent as much water vapor as possible from remaining inside the home. Portable dehumidifiers and humidifiers are also available. 

Another recommendation for every technician, business, and the homeowner is the use of IAQ monitors throughout the home. Real-time monitoring and translation of data over time allows people to see the effects of their activities on IAQ. For technicians and businesses, it is a great way to track the effectiveness of your work over time. Without measurements and testing, you can only guess!

As we work together to combat the spread of viruses in our communities and around the world, the HVAC/R industry has a large opportunity to help educate customers on how to create and maintain a healthy indoor environment. We must take care to avoid fear-mongering and sales tactics geared toward the exploitation of people’s vulnerability and miseducation. Practice integrity, do your research, and implement industry best practices always


– Kaleb

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