Category: All Videos

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.


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

The tech tip today is a video put out by my friend Brad Hicks from the HVAC in SC YouTube Channel. Thanks Brad!

Seal boots to prevent raccoon leaks

Ok, so this has nothing to do with raccoons but I like that photo.

Whenever you are installing duct boxes (also called boots or cans) in an aftermarket application, make sure to place a bead of sealant like mastic or silicone on the flange so that as it presses against the substrate it will seal against leaks to and from the unconditioned space. When installing in a new construction environment where the boxes / boots / cans go in before the substrate you will either want to use boots that already have gaskets or you will want to add a gasket to the flange such as foam tape.  In these cases, it is still a good idea to seal the edge further from the inside once the drywall (or similar) is in place and before the grilles and registers are installed.



Video Transcript

What’s going on guys? here’s another 60-second tech tip, this is on supply and return grills and properly sealing them. As you can see this return grill that I have pulled down was not properly sealed. No silicone or mastic, so basically what’s happening you can see a little bit of wood here when the blower comes on it pulls air that’s pulling unconditioned air from between the sheetrock and the wood that’s framing this box out of the attic and into our Airstream. Since our air filter goes here as well most of this isn’t being filtered, it’s just passing right into the system. As you can see that return is fairly dirty so all of this should be sealed with mastic and usually we just silicone or you can mastic this as well. Same thing with supply grilles, so if you ever have customers that are dealing with dust issues or units getting dirty but the filters aren’t that dirty this could be your culprit. Make sure you’re paying attention to the supplier return grilles and look out for this kind of stuff so hope that helps thanks for watching.

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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