The question we are looking to answer is, should we install the TXV bulb before (upstream) or after (downstream of) the external equalization port? The first thing to know is that the TXV controls the amount of refrigerant flowing into the evaporator coil. The TXV is a metering device that restricts the flow of refrigerant. The TXV measures and adjusts to maintain a specific superheat. It does this by using three pressures. TVX Bulb Pressure (opening force) External Equalizat

In this HVAC training article, we will be discussing how to adjust the fan speeds on an indoor ECM variable speed blower motor and an ECM constant torque/multi-speed blower motor. These blower motor versions can be found in furnaces, air handlers, and packaged units. This is a follow-up to our other article on " Adjusting the Furnace/AC Airflow Speed on a 120v PSC Blower Motor ". If you have not read that yet, I would encourage you to do so! To start, ECM stands for Electr

In this HVAC training article, we will be discussing how to adjust the fan speeds on an indoor PSC blower motor in furnace and air conditioning units. PSC stands for Permanent Split Capacitor and these motors can be easily identified by their direct connection to a capacitor. Remember that CFM stands for Cubic Feet Per Minute. Roughly 400 CFM is needed for every 1 ton (12,000 BTU/HR) of heat removal capacity in air conditioning systems. 350 CFM per ton can be used in humid cl

This article explains how the thermocouple, gas valve solenoid, and pilot flame work on a water heater. I will be discussing 10 problems that may occur that causes the pilot flame to go out along with the solution for each example. The following steps indicate how to light the pilot on the water heater and explains the key components within the water heater that make it work. Lighting a pilot should be fairly simple. 1. Locate the large red/white knob on top of the water heat

In this HVACR Training article, we are using electrical resistance measurements on the PSC compressor terminals in order to determine which tab is Common, Start, and Run. This is used when the tabs are not labeled, there is no plug for the terminals, or there is no electrical wiring diagram available for the wires feeding from the terminals. The steps listed below can be used to test all single speed PSC motors (i.e., compressors, blower motors). Whenever possible, first meas

In this article, we will be discussing methods to test the safety switches in a gas furnace using a multimeter. These switches include the flame rollout switch, thermal limit switch, and the pressure switch. The gas furnace is designed with at least one flame rollout switch to detect flames or high temperature within the combustion chamber. The flame rollout switch is normally closed and opens on high temperature from the flame. The switch is meant to open if the flame is pus

In this HVAC training article, I discuss 20 AIRFLOW Problems that you may find on ducted gas furnaces, air conditioners, heat pumps, air handlers, and packaged units. Some problems happen over time due to lack of maintenance while others may have occurred during the initial installation. Low air flow is a big deal, so it is important to figure out what is causing this issue. For a furnace it could overheat. For an air conditioning system, the evaporator coil could freeze. If

In the world of HVAC, low voltage shorts are a common occurrence on a service call. Low voltage shorts occur when an electrical circuit finds a shortcut to the ground or common that requires little or no resistance, rather than completing the designated path. In an HVAC system, low voltage shorts are often indicated by a blown fuse on a control board or in the circuit wiring. Unfortunately, knowing that a short exists is only the first step. The fuse acts as a safety on the h

A refrigerant leak may be easy to find when the leak is a large one but when the leak is small, finding it can be tedious and time consuming unless the right leak detection tool is used. If a leak exists in a system, the leak may be anywhere such as in the condenser, evaporator coil, line set, or a fitting, component, or joint. Searching all of these areas must be done quickly and with confidence. Regardless of the type of gas within the HVACR system, an ultrasonic leak detec

In this step-by-step installation, we will be covering the full installation of a ductless Mini-Split heat pump system. This system happens to be a Cooper&Hunter Dakota Series Hyper Heat model . This installation process will be very similar to other manufacturer’s Mini-split systems. However, it essential to read the install instructions and flare torque specs of the exact model you are installing. A variety of tools and techniques are needed to complete the installation of

In order to troubleshoot a gas furnace, the technician must have a thorough knowledge of each component that could be in the unit. Understanding how each component works is crucial to fixing the problem! Let's start by going over each of the major components down below! Integrated furnace control board: This board integrates both the ignition control with the blower control all as one board. Depending on the 24v inputs on G, W, Y terminals, it will control the function of the

Diagnosing if a control board is bad on a furnace, air conditioner, or heat pump may seem difficult but here are some simple tips and processes to make the job a little easier. It is difficult, if not impossible to know if a control board is bad if you don’t know how the system it is attached to works. For a furnace, you need to know the sequence of operation for the heat to turn on. ( Check out our video on that .) For an air handler, you will need to determine if the unit i

How can you tell if you have a clogged liquid line filter drier? If there is a noticeable temperature drop from one side of the filter drier to the other, this means that there is a pressure drop. Remember that temperature follows pressure and temperature is something that we can measure on the outside of the tubing. Usually no ports are available at the inlet or outlet of the liquid line filter drier. Filter driers are designed to have an extremely low pressure drop across t

Is there an easy way to tell if a mini-split ductless unit is low on refrigerant? Yes, if the Delta T is low and the system continues to run without reaching the desired temperature, you can check the total superheat to determine if it is low on refrigerant. I have noticed that on most properly charged systems, the total superheat tends to be between 0 to 5 degrees during emergency cool and full speed cooling. The reason that the system can run with this low of a total superh

Why do older coils seem to last a long time but ones that are only 10 or 15 years old leak? Energy transfer efficiency was not as much of a concern on older equipment and the tubing used in these older coils had a thicker outside wall dimension. On newer coils made over the last 20 years, the tubing in the coil is thinner, and in most cases, they have an increased surface area on the inside for quick heat transfer. The picture shows this increased surface area. The problem i

I put this list together to make sure that HVACR technicians don’t have to undergo the same frustrations, loss of time, and expenses that I did when trying to figure out solutions to vacuum problems! I am happy to say that I no longer have issues with my vacuums and if there is a problem, I can usually figure out the solution quickly without frustration! Below are my top 40 tips for techs when pulling a vacuum! Hoses 1. Hoses may be rated for vacuum or just for positive press

Can you check the charge on a system without checking pressure? Sure, remember that the only reason we check pressure is to convert it to saturated temperature. For single and two speed compressors systems, we use the subcooling and total superheat charging methods. I will briefly explain these charging methods using pressure before diving into reading temperatures only in order to check the charge. In order to measure subcooling, we measure the saturated temperature in the

The answer is no because the refrigerant rejects heat in the condenser so the pressure and temperature of the refrigerant should lower. The refrigerant starts off in the condenser as a superheated vapor and after it rejects heat, it changes from a vapor state to saturated. After it rejects enough heat, the refrigerant changes to a subcooled liquid. In this picture, we see a saturated temperature of 105°F and a line temp of 93°F. 105 - 93 = 12°F of Subcooling It is possible f

In this article, we will discuss an HVAC unit’s refrigerant pressure on both the high side and the low-pressure side while the system runs. It is important to know the range of these pressures in order to understand why and how charging and recovery are performed. The first thing to realize is that when a system is off and equalized, the system’s pressures on both the high side and the low-pressure side will match. In the example of an R-410A packaged unit with a surrounding

In a dry climate, certain considerations must be taken prior to installing or servicing air conditioning systems. A TXV metering device and an accumulator are important factors. In a dry climate, a TXV metering device should be installed instead of a piston metering device. Not only is this important for efficiency, the TXV will help protect the compressor somewhat during low indoor humidity and high outdoor ambient temps. The TXV does this by keeping the superheat steady at