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Tech Tips:

HVAC Contractors Guide to COVID-19 (SARS-CoV-2, Coronavirus)

UPDATED VERSION AS OF 4/1/2020 As HVAC contractors, we are tasked with keeping staff and customers safe during the outbreak, and we are relied upon to provide some guidance to customers about how to protect themselves against the virus in the air. For employers and employees looking to navigate the new FMLA/FFRCA legislation, we put […]

Ventilation, Filtration, and Humidity Control: The Holy Trinity of IAQ

At the time of the publication of this article, COVID-19 (coronavirus) is spreading across the world at an alarming rate, and many people have self-quarantined to help slow or stop the spread of the virus. These precautionary measures are prudent and responsible. However, with the increased amount of time people spend inside their homes, there […]

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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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