#condenser

Tech Tips:

In a previous article, I talked about wiring permanent split capacitor (PSC) condenser fan motors. While researching the topic, I realized that there isn’t as much information available on condenser motors as there is on their counterpart—the indoor blower motor. I had never really given it much thought, as I assumed that the condenser motor […]

Universal Condenser Fan Wiring Options

Assessing the Situation It is fairly common for a service technician to come across a failed condenser fan motor in the field. It doesn’t matter if we are talking about really old or fairly new equipment—condenser fan motors sometimes fail. The issue is deciding whether to use an OEM (Original Equipment Manufacturer) or a universal […]

How to Replace a Condensing Fan Motor

Service calls about condensing fan motor failure are quite common. Even though fan motor replacement is a standard procedure for residential split systems, it requires careful attention to safety and detail. This article will give you a step-by-step guide to replacing condensing fan motors. Along the way, we will also explain a few best practices […]

HVAC/R Refrigerant Cycle Basics

This is a basic overview of the refrigeration circuit and how it works. It isn't a COMPLETE description by any means, but it is designed to assist a new technician or HVAC/R apprentice in understanding the fundamentals. First, let's address some areas of possible confusion: The word “condenser” can mean two different things. Many in […]

Condensing Temperature, Condenser Split, and Subcool

In this podcast, Bryan talks about condensing temperature, condenser split, and subcooling. All three of the values are proportional. If one changes, all three of them will change. Saturation is also a critical concept that relates to all three of those, so we also cover those relationships. As you remember, a condenser rejects heat and […]

The Basic Refrigeration Circuit

In this episode of HVAC School, we discuss the entire basic refrigerant/compression refrigeration circuit. We are in the business of moving heat. Heat refers to motion in the molecules. Temperature is the average velocity of those molecules. Heat needs a temperature differential to move. So, HVAC systems absorb heat when the refrigerant is colder than […]

How to Evacuate an AC system, Full Vacuum Procedure

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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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