Month: January 2020

Note: This short series is on the mindset of learning (and teaching) not really a “tech tip” per se. We will be back to the tech tips in a few days. 

I’ve heard and repeated these phrases countless times over the years both at home and at work

That should be obvious

It’s just common sense

How could you miss that

That CLEARLY isn’t good enough

You SHOULD know better

It’s the human condition to forget what it was like before something became second nature to us.

We tend to blur all the intermediate steps it took for us to become competent at something into “common sense” that people just “should know”.

When we see someone turning a screw or bolt the wrong direction we either verbally (or in our head) repeat the phrase

“Righty tighty, Lefty loosey”

Let’s analyze that for a second, what does that phrase mean to someone who hasn’t spent a lot of time with a wrench in their hand.

Turn it right? we are spinning it in a circle so it really depends on how you are looking at it whether it’s right or left is tight.

Hold your hand out in front of you with your thumb pointed down and fingers up. To tighten a bolt we turn right from the top with the bolt facing us. Our fingers turn right but from the bottom where our thumb is it actually turns left. Also, if the bolt is on the other side facing away from us we turn it left from the top to tighten.

We really turn it clockwise to tighten typical threads not “right” but even clockwise is something we learn through feel. If you were going to explain to someone how to tell the difference between clockwise and counter-clockwise what would you say?

“clockwise moves to the right” and then we are right back at the start.

We learn things through experience of

  • Trial and Error (this works, that doesn’t)
  • Compare and Contrast (This is like that or not like that for these reasons)
  • If this happens then that happens (If this, then that)

In the case of a simple phrase like “Righty tighty” we make several assumptions about the person we are saying it to that they know right from left already and that they understand your facing the component being turned and that we are saying right from the top.

But really we aren’t thinking about any of those things… we are really just thinking “This is obvious, stop overthinking it, turn the darn thing right to tighten it”

I can already see the messages –

Why are you complicating this… it’s obvious which way we mean when we say “righty tighty”

It isn’t obvious until it becomes obvious, then it seems to us like it always was.

We may think we learned it because someone repeated the phrase “righty tighty” but we actually learned it because we turned it the wrong way a bunch (trial and error), we learned right a left and clocks via repetitive reinforcement as a kid and it’s enough like the motion of a clock that we make a connection.

Memory Doesn’t Work How We Imagine (Imagining is how it works) 

I often envision my memories like books on a shelf that I pull down and read and then put back when I’m done, safe and sound for access next time.

In this model, I may lose a book or have a hard time finding it but my memory is my memory and it doesn’t change any more than the words on the page change. I may misplace my copy of “Hitchhikers Guide” but when I do locate it “The ships hung in the sky in much the same way that bricks don’t.” just like always (forgive my force-feeding of Douglas Adams line).

The reality of memory is messier and more fluid than books on a shelf

Have you read Neural Correlates of Reactivation and Retrieval-Induced Distortion Published in the Journal of Neuroscience? No? It’s a real page-turner.

The results of the study demonstrate that memory recall is actually quite dependant on the current state of your mind and emotions and surprisingly untrustworthy as exact replicas of the facts.

Modern neuroscience has demonstrated that all memories are recreations of the ideas and senses that you experienced in the past but using the brain of the present.

Think of it this way (compare and contrast in action)

When you take a voltage measurement with a digital, data logging multimeter, what is happening?

You are placing probes on points of differing electrical potential… do the probes measure the voltage? No, they simply transmit the potential to the meter.

Once the voltage gets to the meter, the meter can “measure” the voltage but does the internal electronics display the voltage? No, the display actually shows it in a way that makes sense to us.

If the meter stores the measurement, is it stored in the display?

No, the measurement is stored in memory as a bunch of zeros and ones and can be recalled later and reconstructed into a display later using software designed to make sense of those zeros and ones, therefore, replicating the result.

The difference with the human mind is that our experiences shape and change our software.

As we have experiences our brain encodes this data into our long term memory via neurons that are trained to fire in unison to “recall” a past experience or idea.  When we recall these experiences they are processed with your latest software that may come to different conclusions as to what these signals mean than the original.

The result? sometimes we don’t remember things as they actually were and especially all the little details it took to get from point A to point B.

Once we realize that all of our memories are complete reconstructions of raw data rather than books or photos on the shelf we can begin to understand that concepts that now seem simple, obvious or given were not that way when we first learned them. We likely just learned them through methods and during times that we are now failing to recall.

Lock in Understanding 

On social media, we often get some version of “If you don’t already know that you need to go back to school”. The funny thing about that is the people who say that often have similar blind spots and probably didn’t learn the very thing they now see as “so obvious” in school anyway.

Education at it’s very best is simply a forum where experiences can efficiently be metabolized into understanding

Understand and do, do and understand they go hand in hand. Sometimes we understand something first and then we do it. Sometimes we do something first, become confused, make mistakes and THEN we understand it.

Either way, the goal is to be able to both understand something and do it well. Once we do something long enough and understand it deeply enough it starts to feel simple to us but don’t mistake the fact that it is now simple for your mind as being “obvious” for others.

In order to teach well, we don’t simply vomit out the information we know and expect it sink in. We need to meet the student where they are and facilitate the experiences that will lead them down the path that will result in understanding.

Habits and Reps 

When I was 16 I went to work at a golf course for about 6 months. I really enjoyed golf and I wanted to get better so I figured working around it and playing almost every day would help.

It didn’t, I got worse

While I was getting a lot of reps swinging over and over the things I was doing and my assumptions about what I was doing wrong were incorrect.

I had the experience but I lacked the insight to come to a proper understanding that would result in effective practice.

Many of us learned most of what we know in the field simply because we get so many repetitions of experience in the field. Many of the time bad habits and incorrect thinking are ingrained in the field for this very same reason.

Incorrect assumptions lead to incorrect understanding and bad results.

Like Reagan once said

“It isn’t so much that they are ignorant. It’s just that they know so many things that aren’t so.”

On one hand, we cannot expect anyone to understand anything without experience any more than someone could learn to golf from a book. On the other hand, practice doesn’t make perfect if it is based on incorrect understanding.

To summarize;

  • We all know things because we have a combination of experience and understanding not because “it’s obvious”
  • Our memory is unreliable as to how we learned things and we often miss the little details that got us where we are
  • Trying to separate understanding from experience or vice versa is a waste of time

The next article will be on Trial and Error and how we can use it intentionally to learn and teach.

— Bryan







I walked into a supply house the other day and I was looking at a “universal” expansion valve on the shelf. The friendly guy behind the counter saw me and walked over, after saying hello he offered

“That’s a great valve, it’s even balanced port”.

Now I am a bit of a trouble maker, I should have just nodded and said “uh huh” but instead I asked, “what does balanced port mean?”. The counter guy sort of half shrugged and said: “I guess it means it works on a lot of different systems?”

I would bet that most people in the industry have heard the term “balanced port” and figure it sounds like a good thing but don’t really know what it does. Not long ago, I would have been one of them.

We have all been taught that there are three forces that act on an expansion valve –

  1. Bulb Pressure is an opening force
  2. Evaporator Pressure (external equalizer) is a closing force
  3. The Spring is a closing force

while the system is within its design operating conditions these forces are the primary forces at work that allow the valve to “set” the evaporator outlet superheat.

There is a fourth force and that is the opening force applied by the refrigerant passing through the needle. When the inlet (liquid line) pressure is within the normal operating range this force is accounted for in a normal TXV. In cases where the liquid pressure is higher than usual the force will be greater allowing more flow through the coil and when it is less it will allow less flow.

The result of this effect is fluctuating superheat based on liquid pressure which may be acceptable in small amounts but can become unacceptable quickly on systems that require accurate evaporator feeding or systems that have a wide swing in condensing temperatures and pressures.

Sporlan largely solved this particular issue in the ’40s when they brought the “balanced port” valve to market. While the technology is nothing new it has been improved on over time.

Balanced port TXVs can vary in design but they solve this problem by allowing the inlet pressure to affect the top and bottom of the needle (orifice) equally. This eliminates (or reduces) the liquid pressure as an opening force and instead turns it into a “balanced” force that neither opens or closes the valve.

If you have an application where the head pressure is allowed to change or “float” over a wide range, the balanced port TXV is a great choice.

— Bryan



In these tips and on the podcast we talk a lot about the importance of deep vacuum and deep vacuum using proper processes and tools is the best and really ONLY way to ensure a system is clean, dry and tight.

Just to review that means

Nitrogen purge, flow and pressurize > Cores removed > Vacuum gauge on the system > Large hoses > Vacuum pump tested > Pull to below 500 > perform an isolation “decay” test

This is all great and works just as advertised but sometimes techs can still get frustrated when pulling on systems that were previously in service or that are abnormally wet. This is when nitrogen sweeping and extra heat can come in handy.

Understand the Micron Gauge 

A micron is one-millionth of a meter of mercury column… in other words, a REALLY tiny amount of pressure and it requires a very accurate and precise instrument to measure.

A vacuum or “micron” gauge is a thermistor sensor that relies on heat transfer from the thermistor to measure vacuum level. Because vacuum is a poor conductor of heat the deeper the vacuum the less heat transferred which allows it to measure the vacuum level.

The gauge is calibrated to nitrogen or air NOT refrigerant, so any small pockets of refrigerant in the system or in the oil can interfere with the measurement.

The Challenge

When you are working on a system that previously had refrigerant in it and you recover the charge down to atmospheric pressure, there is still a lot of refrigerant in the system. The result can be an erratic reading on the gauge and “stalling” of the vacuum as refrigerant slowly escapes from the oil.

Sweeping the system with a high-velocity flow of nitrogen can help to displace the refrigerant as well as agitate the oil and help to free it up and remove it.

The same is also true with abnormally wet systems, while the nitrogen isn’t a magical sponge soaking up water it can help to get it moving to flow some nitrogen.

When running into these issues during low-temperature conditions or on systems like freezers where components are still in the cold box, it can be helpful to use a heat gun to warm cold areas or parts that hold oil such as the compressor or accumulator.

You can use heat during deep vacuum and then break with nitrogen to help the process along.

This does not replace the deep vacuum process but can certainly help it along when you find yourself getting stuck.

— Bryan

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