Category: Videos

I was about 13 years old the first time I bent EMT with my uncle. We were doing a renovation at a church, and watching him bend EMT and then getting to do it MYSELF was a truly religious experience.

There are a few things in the trade where workmanship really comes into play such as copper pipework, making up a panel or fabricating ductwork… bending EMT belongs on that list. While most commercial electricians do it every day, HVAC techs and installers only run into an application where we do it on a rare occasion. When that does happen its good to have a basic understanding of how it works. In this video Juan from the The Air Conditioning Guy channel goes over some quick basics on bending EMT

For more info you can read this great guide on bending from Klein

— Bryan

As a technician gains skill they will learn that regularly testing your tools is a huge part of success. It isn’t long in the field before techs find out that just because a meter or gauge gives a particular reading it doesn’t ALWAYS mean it is correct. Vacuum is one of these areas.

Everything in an air conditioning and refrigeration system leaks to some extent, our job isn’t to eliminate all leaks, our job is is to reduce the leakage rate to as low as possible. When using a sensitive micron gauge we find that isolating an assembly and checking the “decay” or standing leak rate is a great way to test and ensure that a system has minimal leaks and moisture. The challenge is that all of the connections in your rig leak and even the vacuum gauge itself leaks.

Some techs attempt to test the leak rate on micron gauge by connecting it to a core tool and then straight to the pump, evacuating the gauge down to very low level and then valving off. If you do this, you will find that every commercially available vacuum (micron) gauge shoots up pretty quickly. This is because the VOLUME of the gauge and coupler are so low that ANY leakage whatsoever has an enormous effect.

In this video Ulises Palacios shows us how to use an an empty recovery tank to better test the leak rate of a vacuum gauge rig.

It is certainly important to test all of your vacuum rig components, just remember that volume makes a huge difference when decay (standing vacuum) leak testing.

— Bryan

In this 60-second tech tip video by Brad Hicks with HVAC in SC. he shows us how and why to remove the weep port plugs on a condensing fan motor. I know from experience that motors can fail prematurely when this practice isn’t followed. Remember that motor orientation dictates which are removed. It (generally) the ports facing down that need to be removed and the ones face up stay in place.

Transcript

What’s going on guys here is a quick 60-second tech tip is on changing condenser fan motors. Whenever you’re changing them, most all condenser fan motors have plugs that are supposed to be removed depending on the orientation of the motor. Since this shaft is facing down into the unit these need to be removed and basically what they do is, they open the weep holes so any condensation or moisture that can get into the motor doesn’t stay in there to corrode the windings and in turn prematurely make the motor fail. So make sure you take those plugs out, if you don’t, like that motor over there you’ll be back within a couple years to replace it again. Just a quick tip make sure you take those plugs out like I said this motor is oriented this way so you want to take the plugs out of the bottom like I just did and your motor will last much longer. There you go thanks for watching.
— Brad Hicks

 

I hear many techs complain about the finicky and ineffective nature of electronic leak detection. So much so that some claim that is is a waste of time altogether. we recently located a leak inside the fins of a ductless evaporator coil, pinpointed to an exact spot using an electronic leak detector. For demonstration purposes, we took that coil and performed a definitive test to locate it in the video below.

A leak detector can be tricky to use so here are some of our top tips –

  • Know your detector. Know it’s limitations, it’s sensitivity and what can cause false positives. For example some leak detectors will sound off on certain cleaners or even soap bubbles. My detector sounds off when jostled or when the tip is blocked.
  • Keep a reference bottle so you can check your detector every time before you use it.
  • Maintain your detector and replace the sensor as required. Most heated diode detectors require sensor replacement every 100 hrs or so.
  • Keep it out of moisture. Most detectors will be damaged by almost any amount of moisture.
  • Move slowly and steadily. Don’t jump around or get impatient.
  • Most refrigerant is heavier than air which means that starting from the top and working down is usually a more effective way to pinpoint.
  • Go back to the same point again and again to confirm a leak. Don’t condemn a component bases on one “hit”
  • Find the leak WITH BUBBLES whenever remotely possible, even after pinpointing with a detector.

— Bryan

When evacuating, the FASTEST way is to use two large diameter hoses connected to two core removal tools and the cores removed. These hoses are then connected to the pump using a tee or evacuation “tree”.

However, when you only have one large hose another acceptable method is to connect the large hose to the suction side and the vacuum gauge to the liquid side alone.

Brad Hicks from HVAC in SC made a nice little video showing how he does this with just one hose. He uses a core tool with the vacuum gauge on the liquid line to ensure that there aren’t and issues with depressing the core, which happens often with certain cores and gauge couplers. The other reason is so that he can valve off the vacuum gauge when he releases the charge or charges the unit to prevent refrigerant and oil from potentially entering his vacuum gauge.

The disadvantage of this setup is that the vacuum must all pull through the metering device which can add time to the process. In the case of a “hard shut off” TXV this method may not work.

Transcript

Well guys here’s another 60-second tech tip video. This one’s going to be on single hose evacuation setups. I get tons of questions on the subject so hopefully, this will clear things up a little bit. It’s very very simple, all I have is two valve core removers here both ports liquid and suction have been removed. On the liquid side, I’ll have my micron gauge. In this case the BluVac Pro and on the suction side I have my Appion hose. This is a six foot(1.82 meters), 1/2″ diameter 1/4″ by 3/8″ and then, of course, my vacuum pump. No special fittings or anything anywhere very very simple setup and very effective. Just to give you an idea I’ve been running a total of 24 minutes right now and my decay test has another two minutes I’ve set for 10 minutes a day so another two minutes and we’ll be good to go and as you can see single hose setup very very effective and as you can see I have it isolated. I’m still reading my micron gauge and everything in the system.  Hope that helps just a quick rundown have any questions feel free to ask.
— Brad Hicks, HVAC in SC

When you first start checking your supply air with a thermo-hygrometer you may notice that the relative humidity is REALLY HIGH. Often the RH in a supply duct will be between 85% and 96% relative humidity on a system that is functioning as designed. The reason for this is fairly simple.

In order for dehumidification to occur the air must reach dew point, otherwise known as 100% relative humidity

Jim Bergmann explains it this way. Think of a sponge being like air and when it is fully expanded it is like the air in the return. When the sponge is fully saturated and can accept no more water it is at 100% RH and when it is completely dry it is at 0% RH. Let’s imagine that the sponge is 50% saturated and full size in the return. When that sponge (air) goes over the evaporator coil it is compressed, because colder air can hold less moisture. Once that air is compressed (cooled) enough it will begin to give up moisture. This point at which it starts to give up moisture is called dew point or 100% relative humidity. Once that air leaves the coil it still remains in approximately the same temperature state (compressed sponge) as it was when it went over the coil. This means that unless heat is added or removed from that air, it will remain at 100% relative humidity.

So why is it less that 100% RH in the supply?

There are several reasons why the air in the supply will be slightly below 100% in the supply. First is contact factor or bypass factor which are both terms used to demonstrate the efficiency of a coil at “contacting” the air. The greater the surface area of the coil and the longer the contact time of the air on the coil the more efficiently heat will be transferred from the air to the coil.

Because no coil is 100% efficient, there will always be some air molecules that leave the coil warmer than others, this causes the airstream to be warmer overall and decreases the RH of the air stream. You will notice when a system has a higher coil air velocity (speed) it will have a higher bypass factor (lower supply humidity). When you run lower coil air velocity the bypass factor will drop and the supply RH will increase.

There is also some heat added by the blower motor and possibly even the cabinet or supply ductwork. This added drybulb heat results in a warmer airstream and thus some additional moisture capacity. Imagine a slight expansion of the sponge due to heat from the duct walls and the blower motor.

Once that supply air exits the duct and mixes with the room air it is allowed to “expand” again and the relative humidity drops below what it was initially. This is why supply air has a high RH in cooling mode.

Here is a video we did on the topic –

— Bryan

 

Recovery is the removal of refrigerant from a system to either store and send in for recycling or to reintroduce back into the same system.

Here are some top tips –

  • Make sure your tank is empty and evacuated to 300 microns if you plan to return the refrigerant back into the system.
  • Never mix refrigerants.
  • Purge hoses before recovery.
  • Use a flare line drier on the inlet of the machine to increase the life of the machine and to filter and dry the refrigerant. These must be replaced regularly.
  • When recovering into a tank using the standard method invert the tank and pump into the vapor port on the tank.
  • Remove Schrader cores before recovery for faster recovery and a cooler tank.
  • Use larger gauge hoses with no core depressors for faster recovery.
  • Check Recovery machine inlet screens regularly and clean or replace as needed.
  • Some machines require oil to be run through the machine from time to time. Read manufacturer specifications.
  • If your tank becomes hot you can either place it in a bucket of water or run water over the tank.
  • Do not leave refrigerant in your machine during storage. If your machine has a purge mode make sure to purge the refrigerant out of the condenser (see manufacturers specs on your machine).
  • Most HVAC systems holding under 200 lbs of refrigerant are not required to be pulled into a vacuum during recovery. See this chart from the EPA.
  • Weigh the refrigerant out and do not fill the tank to more than 80% of the REFRIGERANT capacity, not just the water capacity.

We cover all of this and more in this video –

— Bryan

On occasion you will either find a furnace or be tasked with installing a furnace where the coil overlaps the edge of the furnace because the coil is wider. In the case of a Carrier CNPVP coil you need to ensure that you align the coil according to manufactures specs or you risk cutting off about 1/3 of the airflow.

The best case scenario is to use a coil that is a sizer match for the coil or to buy or make a  tapered metal transition between the furnace and the coil. The the case of the CNPVP the manufacturer allows the coil to be offset to the left.

In this video we illustrate replacing a leaking coil and reconfiguring it in the proper orientation.

— Bryan

There are many acceptable methods for making a wire splice and you need to consider many different factors when making a splice. Here are a few considerations.

  • High Voltage vs. Low Voltage – If the connection is 24V or less it USUALLY has fewer NEC (National Electrical Code) rules and regulations about how the connections are made and in some cases you are safe making an inline splice without a box. When making an inline splice on high voltage conductors you MUST use a properly UL rate splice or a box.
  • Dry vs. Damp Conditions – If it’s ever going to be exposed to moisture you need to think about shorting and corrosion. Your splice should keep water away from the conductors themselves. if there is any chance of moisture.
  • Concealed vs. Accessible – If you are going to bury the splice in the ground or in a wall it needs to be RATED for that purpose and you need to be darn sure that splice will last as long as the conductor itself.
  • Quality of Connection – Every connection needs to be good, but in cases like communication or AV wires it needs to be PERFECT. Think of that new high efficiency, super fancy communicating HVAC system you are installing. Those comm connections need to be good.    
  • Tension the Connection is (or may be) Under – In other words is the wire stretched or is there a chance it might be stretched or pulled later. For example, if a splice is going to be pulled inside a conduit, there is a good chance it will be pulled out someday. If the next guy tries to pull it out and it comes apart, your name will be cursed.
  • Aesthetics  – If the splice looks like a hunk of junk, it will be assumed it is a hunk of junk by everyone who sees it. Neat workmanship matters.

Here are a few options for splicing wires depending on application –

Bad Options 

Splicing any high voltage conductor in an “open” manner or in way that is not specifically rated. In most cases get a UL rated connector and make the connection inside a UL / NEMA rated rated box or assembly.

Making a splice by just twisting wires together and putting electrical tape on top. Just don’t.

Using wire nuts and creating a big ball of wires and running electrical tape over them until it looks like a giant blob of tape.

Good Options

Use wire nuts on low voltage or control wire in dry and accessible conditions but twist them so the wires stay neat and lay half of the conductors in one direction and the other half in the other direction and tape up in a neat fashion.

The same type of configuration with 3M Scotchlok crimp connectors for better moisture resistance than wire nuts.

In some mildly damp conditions you may be able to use self fusing silicone tape for a more water resistant layer than electrical tape.

Use butt end connectors on stranded wire or if using small gauge single conductor wire (like 18ga stat wire) you can double the end of the wire over before making a crimp. When making a crimp ensure that that the actual crimp is made on the side of the connector OPPOSITE  the seam. Once you make a butt end connector pull HARD on it totect and ensure that no bare wire is exposed outside of the insulator.

Better Options 

Use heat shrink butt connectors and stagger the connections to reduce the bulge. Heat the connectors to seal them, then run a piece heat shrink over them all. I found this 4:1 shrink ratio, marine grade heat shrink that should do a great job or water proofing. Heat shrink can be a real life saver and you can use a heat gun or a small butane torch to heat it up. Coincidentally they also make little, portable butane soldering irons as well.

For better connection quality and strength… that’s when you may consider the fabled NASA Splice!

When making a soldered splice make sure to use rosin core solder and wipe off the rosin flux before covering the splice to help prevent corrosion. Remember to run the heat shrink over the cable and the individual conductors BEFORE you start making the splices to prevent sadness and yelling.

Best Options

The best options are to just run a new wire or make the connections inside of a rate box with proper connectors. Sometimes the best way is the simplest way.

 

— Bryan

In this video we cover the basics of using the Testo 510i with a pitot tube to do a duct traverse and easily calculate Velocity in FPM and volume in CFM on a small 8″ duct. Using this method is handy because you can use the reliable, accurate and inexpensive 510i to perform the measurement without any other equipment other than tubes and a pitot tube.

As stated in the video, a pitot tube is best (most accurately) used in the following conditions –

  • Medium to High Air Velocities
  • With 4 -8 feet of hose
  • In low turbulence air at least 8.5 diameters downstream of any turns, fittings or diffusers (I was less than this in the video resulting in lower accuracy)
  • In a duct at least 30 times larger than the pitot tube diameter (It was less than this in the video resulting in lower accuracy)

 

For more information see the following links –

Dwyer Guidelines

TruTech Tools Traverse Quick Chart

TruTech Measuring with a pitot tube

Testo 510i specs

Video on the performance of a rectangular time average traverse

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