Month: October 2019

Tech Tips

5 Terror Inducing HVAC/R Stories & Facts

October 31, 2019 By No Comments

As the evening approaches on this All Hallow’s Eve, Reformation day or Halloween (depending on your preference), let us take a moment to focus on some of the truly terrifying elements of our trade, because the Scariest stories are TRUE.

Real Ghost Stories 

The year was 1921 and a wealthy family purchased a new home in quiet part of town. It was a large, old building and the family was excited to live in such a majestic home.

The trouble started almost right away and the lady of the home (referred to only as Mrs. H) began to recount her experiences in the home to her doctor in letters that were later published.

This house was lit by gaslights and had servants quarters and passageways, a perfect house for a haunting. From Mrs. H’s account to her doctor:

“One morning, I heard footsteps in the room over my head. I hurried up the stairs. To my surprise, the room was empty. I passed into the next and then into all the rooms on that floor, and then to the floor above to find that I was the only person in that part of the house. Sometimes after I’ve gone to bed, the noises from the store room are tremendous, as if furniture was being piled against the door, as if china was being moved about, and occasionally a long and fearful sigh or wail.

“Sometimes as I walk along the hall, I feel as if someone was following me, going to touch me. You cannot understand it if you’ve not experienced it. But it’s real. As I was dressing for breakfast one morning, B, who is four years old, came to my room and asked me why I’d called him. I told him I’d not called him, that I’d not been in his room. With big and startled eyes he said, ‘Who was it, then, that called me? Who made that pounding noise?’

“I told him it was undoubtedly the wind rattling his window. ‘No,’ he said, ‘It was not that. It was somebody that called me. Who was it?’ And so on he talked, insisting that he’d been called and for me to explain who it had been.”

The hallucinations continued, with the family feeling the presence of the unknown. They experience hauntings, rattling beds, lethargy, and temporary paralysis. Even the plants began to wither and die.

Mrs. H continues:

“Some nights, after I’ve been in bed for a while, I’ve felt as if the bed clothes were jerked off me. And I’ve also felt as if I’d been struck on the shoulder. One night I woke up and saw, sitting on the foot of my bed, a man and a woman. The woman was young, dark and slight and wore a large picture hat. I was paralyzed and could not move.”

After speaking with different people about their malady with the spirit realm, a relative suggested that they are being poisoned. He had heard similar accounts from people poisoned by combustion gases experiencing similar symptoms.

It turned out that the gas lighting and the furnace were dumping carbon monoxide in the home. As soon as the furnace was properly vented their ghosts disappeared and life returned to normal.

This preceding story is one of my favorites from the Podcast and Radio Show This American Life which was brought to their attention by Albert Donnay, toxicologist and CO expert.

It makes me wonder how many of the hauntings in these old homes is due to CO rather than the spirit realm.

The Deadly Gift 

The year was 1938 and Walt Disney was just off of his first blockbuster success with his film “Snow White”.

Walt and his brother Roy decided to buy a new home for their parents in North Hollywood, finally moving them down from Oregon to be near their now famous sons. In November of 1938 their mother complained to Walt that the furnace smelled strange so he sent some of his studio repairmen over to have a look.

Several days later the housekeeper found both of Disney’s parents unconscious in the home, with their mother Flora dying shortly after. Their father recovered shortly after, but many accounts say that Walt never forgave himself and was later heard mumbling

“I told those techs to buy a BluFlame combustion analyzer from TruTech tools before they went out. Heaven knows if they used the coupon code getschooled they would have had significant savings!”

All of my facts in that story are definitely, 100%,  maybe true.

In all seriousness, testing combustion and using low level CO monitors in homes and for yourself while working around combustion appliances can save many lives as well as undiagnosed illness and even a haunting now and then. See anything wrong with the furnace above?

Roofs and Ladders 

We were called out to a new high rise condo building in our area to maintain a bunch of rooftop equipment and what we found was an acrophobic nightmare. No guard rails, no parapet wall… just equipment, with much of it a few feet from the edge with sure death awaiting below.

Our service manager promptly called the customer and let them know that we would be back once they had measures in place to make the equipment safe to service.

Guess what they responded?

Nobody else has a problem with it

Whether it’s equipment that cannot be safely serviced according to OSHA 1910.1 like the ones above or extension ladders put up through scuttle holes 20′ straight up we need to start making customers responsible for providing us with safe working conditions rather than just doing it because “Nobody else complained”.

Maybe a harness tied off can work the first time until they get a proper permanent ladder or guardrail or WHATEVER WORKS, but just going back time and time again and putting ourselves in danger is the definition of insanity.

Moisture Problems 

The pager went off at 2 AM… I was on call AGAIN because the guy who WAS on call quit right in the middle of his week… he just couldn’t take this thing beeping at all hours. I grabbed the on call cell phone that was as long as your forearm and dialed the after hours voicemail line… YOU HAVE ONE NEW MESSAGE… the familiar robotic voice chirped at me.

The man in the recording sounded panicked “You were all out here earlier today and replaced an evaporator coil and now my WHOLE CEILING JUST FELL IN!”

Well… It wasn’t his ENTIRE ceiling, just a large portion of his master closet ceiling over his suits and ties and patent leather shoes. All of this happened because the tech out earlier that day hadn’t paid attention to how he strapped drain and there was a newly formed sag resulting in a double trap. Add in the fact that he had “moved” the pan switch out of the way and forgot to reinstall it properly.

Water damage, mold and mildew, lawsuits and 2 AM service calls can be prevented by paying attention to –

  • Drain pitch
  • Float Switch Location and Testing
  • Drain Cleaning
  • Pan Positioning
  • Proper configuration of drains in horizontal applications
  • Drain Cleaning

Many of the biggest nightmares in my career have been due to drain issues and moisture due to surfaces hitting dew-point. Keep the moisture where it belongs and the pager will stay quiet… who has pagers anymore anyway?

The Tiny Plug

I was sitting on the couch the other evening watching football when my oldest son who rarely has much to say piped up and said

“Dad, what happens if you test gas pressure and forget to put the plug back in”

The hair raised on parts of me where hair shouldn’t raise.

Turns out he was just curious and hadn’t actually forgotten to put the test plug back in on a valve but it did get me thinking that there is nothing quite so scary in our trade as a combustible gas leak and none more odious than “forgetting” something that critical.

When working on gas appliances always make sure to leak check connections and for gas bypassing the valve during the off cycle using a combustible gas leak detector…. Trust your nose as well… if you smell gas odorants then investigate.

Most of all…

Please…

Whatever you do…

Don’t forget to put the little plug back in after testing the gas pressure.

Also watch out for razor blades in your apples tonight… or better yet… don’t eat fruit being handed out during Halloween. What sort of demented psychopath hands out fruit on Halloween?

— Bryan

Tech Tips

Aftermarket Motor Selection & Considerations

October 29, 2019 By No Comments

This article is written by technician and HVAC School community star Kenneth Casebier… Thanks Kenneth!

When looking at replacing a single phase A/C motor with an aftermarket motor from your van, there’s a few things you should know and pay attention to.

First, the factory OEM motor is always going to be the best option especially when talking about blower motors in a furnace or fan coil unit as that motor was specifically designed for the static pressure and application of the unit. Sometimes this isn’t always an option and for those times there’s a few guidelines that will aid in ensuring the motor of choice will be a good decision for both the tech and the consumer.

The first hard fast rule when selecting a motor is going to be frame and size. The frame of the motor needs to match the application, the last thing you want to do is modify a piece of equipment just to install a motor that may fail because of improper installation and now the equipment may not accommodate the right motor because of the modifications made. The actual depth of a condenser fan motor is very important as an aftermarket motor where the body of the motor is taller than the original, it can create a situation where the blade wont be positioned properly in the cabinet/shroud leading to incorrect amounts of airflow and potentially causing issues with obtaining the correct amp draws for reliable performance. Blade position can be EXTREMELY important to condenser airflow and should be carefully considered especially when up-sizing the HP of a motor.

The next most important consideration is amps. The amp draws need to be similar to the factory motor. Always check the data plate as the motor you’re removing may have been changed with an improperly matched motor thus why you are there now. A good rule to follow is keep amp draws within + or – 5% of the original but as close as possible or exact is a best practice. You have to keep in mind the blade, blower wheel, and duct work or shroud are going to affect the ability to properly load up a motor. If you choose a motor too far out of specs for the application you may find yourself in a potential situation for a prematurely failing motor.

(Note from Bryan: If you are replacing an OEM motor with a more efficient motor such as replacing a PSC with an ECM the amperage may go down in those cases and still be acceptable)

Horsepower is the biggest value that there seems to be some confusion on. An easy way to make a wise choice when selecting an aftermarket motor is NEVER DECREASE HORSEPOWER! Keeping the HP the same or increasing by no more than 1 value is a safe practice that will keep you from going back and replacing the motor again.

An example of this would be if you have a failed OEM ¼ hp motor, a “like” 1/3 hp would be an acceptable option, however a ½ or ¾ hp motor may work but will likely cause size issues and will be more costly to operate for the end user and therefore a bad choice.

The last major consideration when selecting a replacement motor is RPM, in PSC motors you want the match to be exact. A 1075 RPM PSC motor is 6 pole motor with a synchronous speed of 1200 RPM and a 825 RPM motor is an 8 pole pole motor with a synchronous speed of 900 RPM. Some motor manufacturers will use slightly different RPM ratings such as 1100 vs. 1075 but this is still a 6-pole motor and the 1075 can replace the 1100.

Additionally it is good to look at the bearing type used when replacing with ball bearings having a longer life but often noisier than sleeve bearings. Also consider the ambient temperature rating of the motor and chooser higher temp rated motors in more extreme ambient conditions where appropriate.

Always use the proper sized capacitor when replacing a motor and it is a good idea to replace capacitors with motors as a precaution.

Remember, no after market motor is going to be an “EXACT” replacement and for that reason I always recommend the factory OEM when possible. In extreme temperatures I know getting the equipment operational can be a driving factor in the decision making process and I’ve even “loaned” a motor to someone until I could order and return with the OEM. This can incur extra costs to the owner but it’s still better and sometimes cheaper in the long run than leaving an improperly applied motor in a system.

— Kenneth Casebier

Tech Tips

Testing a Thermocouple

October 26, 2019 By 5 Comments

First, a thermocouple is not a flame rectifier like a modern flame sensor. A thermocouple actually generates a milivolt potential difference when it is heated by a flame.. Just to get that out of the way for any of you newer techs who are used to modern flame sensors.

With higher efficiency gas fired equipment being the norm for replacement systems, thermocouples and standing pilots are becoming a thing of the past. Newer appliances do not typically utilize a standing pilot, opting instead for hot surface or spark to pilot ignition. These types of ignition systems have benefits over standing pilot, from increased reliability and longevity to higher efficiency numbers. But there are many appliances in the field that still use a standing pilot, and a good service technician should be able to diagnose a thermocouple issue.

Many of you will say-

“Why even check the thermocouple? It’s a 5 dollar part, just throw a new one in!”

“Why are you so lazy? Do you even HVAC in real life or just on the internet?”

Yes, I know thermocouples are cheap and I am all for replacing them when they need to be replaced, or while replacing a gas valve or pilot assembly. But over the years I have seen a lot of guys ( me included) go on calls for pilot issues, find a pilot blown out, relight the pilot, and then because it’s the easiest, quickest fix, replace the thermocouple, only to have the same customer call in a day or two later with the pilot being out AGAIN. And when the tech goes back and relights the pilot, then what? Is that brand new thermocouple bad after a few days? Probably not. There is probably some other issue, but checking the thermocouple millivolt production is the first step for a proper diagnosis.

So how does a thermocouple work? Well, I’m no scientist ( I’m barely a writer), but I’ll tell you what I know. When different metals are joined, and there is a temperature difference between them, a magnetic field occurs between the joints where the different metals meet. The heat of the pilot flame is the source of the temperature difference in a normal pilot system. Through this process, a small amount of current is produced, generally around 30 millivolts. This voltage is sensed by the gas valve and is used to keep the pilot valve internal to the main gas open. If the pilot goes out, the heat that is generating the potential (voltage) is lost, thus current stops flowing to the gas valve, and the pilot valve is closed, closing off fuel to the pilot assembly. The thermocouple is a safety device. If the pilot flame goes and the pilot valve doesn’t close, the burner compartment and potentially the room the equipment is in can fill up with gas. That the consequences of that would require a different article.

When should you check a thermocouple? I am in the habit of checking thermocouples when I encounter them, whether it’s on a maintenance inspection or a service call. If you are in the habit of checking them, it usually doesn’t take more than a few minutes. If the millivolt measurement is less than 26-27, I typically recommend replacement.

To check a thermocouple, you need a multimeter that is able to measure millivolts. It is typically shown as mV or is just the third decimal over on the DC voltage reading. Remember, the meter should be set to DC voltage.

It’s also helpful to have a extra set of hands, but it is very possible to perform this check by yourself if you hold your tongue correctly (or just use alligator clips). First, disconnect the thermocouple from the gas valve. Then light the pilot. Most gas valves have a turn knob that has to be set from On/Off to Pilot. There usually is a push button that is pressed to manually open the pilot valve, sending gas to the pilot assembly in order to light the pilot. The trick is to light the pilot, and position the meter leads in the proper place to read the voltage. The push button must be depressed through the whole check. With the thermocouple being disconnected from the gas valve for checks, the pilot valve should not stay open and the flame should go out when the push button is let up.

Put on meter lead directly on the gas valve side of the thermocouple. Put the other lead on the copper line as shown by my right hand in the picture above. While holding the meter leads in this position, light the pilot. The thermocouple needs to heat up for 30 seconds to 1 minute in order to obtain a proper reading.

30 millivolts is the desired reading, with a swing of plus or minus 5 millivolts. If the readings are in that range, and you have been having pilot failure issues, more than likely there is some other cause. Dirty pilot assembly/ orifice is the most common other issue I encounter, but it could be down draft/flue or combustion air issues, fuel pressure problems, or a failing gas valve. But as stated above, the thermocouple should be eliminated as a potential issue before moving on with a proper diagnosis. Don’t throw parts at a problem and see what sticks. With thorough troubleshooting, you can save a lot of time, headaches, and maybe the customer a little bit of money and frustration.

— Justin Skinner

Tech Tips

AHR NATE Class + Test

October 24, 2019 By No Comments

Title: NATE Testing & Review

Description:

Bryan Orr with HVACRSchool.com will offer a general, technical NATE review from 8am-11:30am and proctor a session of North American Technician Excellence (NATE) technician certification testing in the afternoon from 1pm-5pm.

The Review will cover elements of the CORE, Air Conditioning and Heat Pump exams and how the concepts apply to the field as well as some fun and terrible Dad jokes.

Price = $200.00 for Test & Review

ENROLL NOW

Tech Tips

HP, Motor HP, BHP, Motor Watts

October 24, 2019 By No Comments

Brake Horsepower (BHP), motor nameplate HP, and the actual electrical power (watts) a motor will consume are different, but related concepts. This gets confusing, so we will tackle them one at a time.

Let us start with simple definitions of work, power, and horsepower.

Work = distance in feet x force in pounds, both applied in the same direction.

Power = time rate of doing work, or work / time. Some units of measuring power are watts, kilowatts, HP, etc.

Horsepower (HP) is defined as doing work at the rate of 33,000 ft x lbs / minute. A horse can do work at this rate continuously without being overloaded. A human cannot sustain doing work at the rate of 1 HP for very long. There is an interesting video of an Olympic cyclist on a stationary bike generating enough power to operate a toaster at @ 700+ watts (746 watts = 1 HP).

He is exhausted after powering the toaster just a few minutes to toast 1 piece of bread. Put another way, imagine continuously lifting an endless supply of 200 lb barbells from the floor up to a height of 7 feet (clean & jerk). To do work at the rate of 1 HP, you would have to lift @ 24 of these barbells up 7 feet, every minute. Every minute, 24 barbells, 200 pounds each, lifted up 7 feet. 33,000 ft x lbs / minute / 7 feet x 200 lbs = 23.6 barbells / minute. This helps us understand why it takes approximately five people to do the work that one horse can do.

Motor nameplate HP indicates the amount of mechanical HP a motor can safely deliver via its shaft without overloading/overheating. Motors are not always delivering full nameplate HP to the load they are driving. The load required by fans, pumps, and compressors usually depends on the fan or pump’s design, the flow rate (cfm, gpm) it is handling, and the pressures that are developed. Thus, a motor with the capability of 3 HP may be driving a load that only requires 2 HP.

Brake horsepower (BHP) refers to the actual mechanical horsepower received at the shaft of the driven machine, such as a fan, pump, compressor, etc.

The watt is also a unit of power. 1 mechanical HP is equivalent to @ 746 watts. Electric motors do not operate at 100% efficiency, thus some of the wattage consumed by a motor converts directly to heat. The rest (the majority) of the wattage provides useful mechanical shaft power to the load that is being driven. For example, a 3 HP motor that is fully loaded and is operating at 90% efficiency will consume a total of 3 HP / 0.90 = 3.33 HP in electricity…or 3.33 HP x 746 watts / HP = 2,487 watts. Of the total 2,487 watts of power being consumed by the motor, only 3.0 x 746 watts / HP = 2,238 watts are converted to useful mechanical shaft power.

To avoid confusion, make sure you understand these different units, or ways of measuring & expressing power.

Steven Mazzoni

HVAC/R Instructor

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