#diagnostics

Tech Tips:

The Evolving Career of the HVAC Contractor: Embracing Change to Stay Ahead

This tech tip was written by Shelby Breger, co-founder of Conduit Tech. You can check out everything Conduit has to offer and learn more about that interesting platform and how it helps contractors at https://getconduit.com/. Thank you, Shelby! Before starting Conduit Tech, Marisa and I spent a year doing everything we could to learn about […]

Tunnel Vision and How to Avoid It

How many times has the following situation happened to you? You're on your way to that final service call. While you're listening to the customer explain their complaints over the phone, there's this precise moment where you've thought: “I know what it is already. This will be a quick one.” Sometimes, intuition proves to be […]

Q&A – Why Didn’t You Notice it Last Time? – Short #210

In this short Q&A podcast episode, Bryan answers Edward's question about how to deal with customers who ask, “Why didn't you notice it last time?” There isn't an easy answer to that question. The truth is that air conditioning and home health and comfort issues are complicated, and it's entirely possible that an issue […]

Q&A – RTU Tips – Short #196

In this short Q&A podcast episode, Bryan answers Jeremy's question about checking the charge on rooftop units, and he gives some RTU tips. Rooftop units often come in sets, so you can use a thermal camera to look at all of the RTUs and compare them. A thermal imaging camera may even show you where […]

The Launch of a Revolutionary Software w/ Jim Bergmann (Podcast)

In this episode of the podcast, Jim Bergmann talks about the launch date of the measureQuick (MQ) app, what it will do, why he made it, who it is for, and why it's different than anything else that came before. MeasureQuick is a universal measurement platform that incorporates Bluetooth to display, store, and interpret measurements. […]

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In this short podcast, Bryan talks about evaporator coil placement based on a question submitted by a listener, John. Evap coil placement differs in furnace applications versus air handlers.

When we use air conditioners with furnaces, we usually put evaporator coils on the positive side to protect the heat exchanger from rusting out during the summer (due to condensation and the chemical reactions that can occur with the metal heat exchanger). However, when it comes to air handlers, they’re usually on the negative side. The coil is usually on the negative side of a fan coil or air handler because it keeps the blower motor cooler (though that doesn’t make a huge difference in terms of performance).

The HVAC system will lose fewer BTUs to leakage when the coil is on the negative side, which is better for energy efficiency; those BTUs can reach the conditioned space rather than the closet, garage, or wherever it is stored. Pulling air over the evaporator coil on the negative side, however, could potentially lead to greater turbulence.

We run into challenges with evap coil placement on gas furnaces when we have dual fuel systems (a heat pump and furnace working together). You can’t run gas heat over a heat pump coil due to the high head pressure, so a parallel setup would avoid the risks of high head pressure (downstream) or rusted-out heat exchangers (upstream).

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