What is a Transformer and How does it work in your HVAC System?

Posted: December 27, 2022

Transformer's Work in HVAC System - PartsHnC

What is a Transformer? The simplest definition of a transformer is an electromagnetic device that transforms power. Then what does that imply? How does it manage to do this? Firstly, let us take a look at how they are constructed. Transformers consist of three primary components: a ferromagnetic core and two sets of wire coils. The primary and secondary windings are the terms used to describe the coils. 

Rheem and Lennox are two major manufacturers that produce transformers for HVAC systems. They are known across the world for their high-quality standards, innovative engineering, and reliability.

Table of Contents:

What is a transformer in your HVAC system?
What are the different types of transformers?
What is a furnace transformer?
AC transformer
How does a furnace transformer work?
What is the purpose of an AC transformer?
Signs of a bad transformer 
What causes a furnace transformer to blow?
How to test the furnace transformer?
How to test your transformer on your ac?

What is a transformer in your HVAC system?

The transformer's primary winding receives AC current through the coil, which causes the magnetic field to pulse. To avoid wasting energy, the magnetic field between the primary and secondary coils is guided by the transformer's core. The secondary coil's electrons are compelled to move once the magnetic field enters it, using electromotive force to produce an electric current (EMF).

The fundamental job of a transformer is to increase or decrease the voltage going from the primary to the secondary windings. To achieve this, just change the ratio of coils on one side to the other.

What are the different types of transformers?

There are different types of transformers used in HVAC systems. They include furnace transformers, AC transformers, heat pump transformers, and others. 

The most common one is a step-up transformer, which boosts the voltage by changing it from high-voltage AC (110 volts) to low-voltage AC (240 volts). This type of transformer is commonly seen in residential and commercial buildings. Another type of transformer is a step-down transformer, which converts low-voltage AC (240 volts) into high-voltage AC (110 volts). This type of transformer is commonly seen in industrial buildings with power generation facilities. 

As we know, various types of transformers are used in different HVAC systems, so let's examine how they work specifically.

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What is a furnace transformer?

The furnace receives power through a furnace transformer. The furnace transformer's main function is to convert high voltage input into a lower voltage output.

Timers, ignitions, circuits, and temperature controls are primarily managed by these furnaces. It serves to maintain the machine's voltage at a set level.

Furnace Transformer - PartsHnC

AC transformer

A device that modifies the voltage in electrical circuits using alternating current (AC) is known as an AC transformer. Stepping voltage levels up and down is significantly simpler with AC than with DC, which is one of the main advantages of AC over DC for electric power distribution.

A magnetic circuit is not used by AC transformers to carry the electrical power produced by the voltage and their supply support from one winding to another, nor do they alter their frequency in any way. It can be used to increase or decrease the present level.

The components of an AC transformer that make it function properly are primarily the core, winding, insulating materials, transformer oil, tap changer, conservator, breather, cooling tube, Buchholz relay, and explosion vent.

AC Transformer - PartsHnC

How does a furnace transformer work?

A transformer's primary function is to regulate voltage. Controlling the voltage in accordance with the circuit breaker or other electrical devices is advised.

To operate an Arc furnace, this is necessary. You'll discover that certain furnaces require 24 volts to function. Since every house's typical voltage output is 120 volts, the transformer will lower your home's voltage to the appropriate level for usage in your furnace. Some furnaces, both electric and gas ones, may have varying voltages.

There is a danger of blown fuses, system shortages, or occasionally even a significant power outage if the transformer is controlled improperly.

If the furnace is mechanized improperly, it could potentially sustain harm. This could result in a loss of money and put you in a bad situation.

What is the purpose of an AC transformer?

A transformer is a piece of permanent equipment used to change the voltage of an AC supply to sense a change in current. A magnetic core that has been laminated connects the two windings of this transformer.

The primary windings AC source and the secondary winding load are connected to this winding when there is a primary and secondary winding.

An alternating voltage is applied to the primary, and its main job is to change the magnitude. The number of alternating e.m.f. turns affect both the primary and secondary number of turns.

When an alternating voltage is applied to the primary, an alternating flux is produced in the core. When a load is connected across the secondary winding, the secondary emf causes current to flow through the load to the second winding. 

Signs of a bad transformer 

There are a few signs of a bad transformer. These include:

  1. Humming and Vibrating - Transformers typically make a humming sound. It is created as a result of the iron core or laminations' expansion and contraction. However, if this sound suddenly increases and is accompanied by powerful vibrations, your HVAC system may have a faulty transformer. Other factors like improper installation or a bad capacitor could be the source of the vibrations and humming sound. Therefore, it is advisable to wait for a specialist to arrive and determine the true source of the issue.
  2. Tripped Circuit Breaker - The circuit breaker typically trips when the HVAC unit's transformer malfunctions. It trips in order to prevent a voltage spike. A power spike can seriously damage the furnace and air conditioner by frying numerous elements all over the devices.
  3. HVAC System Not Working - Even with a sufficient power supply, your HVAC equipment won't operate if the transformer is defective. This safeguard guard against serious harm to the device.

The existence of a transformer fault as the cause of the HVAC unit's problem cannot be proved with absolute certainty. This can only be learned through the process of elimination. The HVAC expert will start by addressing the most likely and straightforward reasons why the unit could not be operating. When everything else fails, they will address the more significant reasons, one of which is a faulty transformer.

What causes a furnace transformer to blow?

There are numerous potential causes for a furnace transformer to blow, but the most frequent ones are lightning strikes, overloading, wear and corrosion, power surges, and moisture. Whatever the cause, the outcome can be impressive. Mineral oil is used in transformers to keep them cool. The wire may become overcharged and produce heat and a spark. The transformer may finally burst due to this extreme overpressure, which may result in a loud boom, a flash, and possibly a fireball that would send up a significant plume of smoke that might be visible from a great distance.

How to test the furnace transformer?

Testing a furnace transformer is a task that requires expertise and knowledge in the field of electricity. However, this task can be done by individuals with just some basic knowledge about electricity and how to test transformers. 

It is important to test the transformer before connecting it to the power source. This will help you avoid any damages or injuries that could be caused by faulty transformers.

Testing a furnace transformer can be done by plugging in a tester and checking if the voltage is within safe limits. If the voltage is not within these limits, then you should replace the transformer with a new one.

How to test your transformer on your AC?

Understanding how to test your transformer on your AC is a crucial step for any homeowner. To test the transformer, you will need a multimeter and a voltmeter. If you don't have these items, you can purchase them at your local hardware store. 

There are two ways to test a transformer: one is by measuring the voltage across the terminals of the transformer and the other is by measuring the current through the terminals of the transformer. 

You can use either method to test your transformer, but it’s best to use both methods in order to get an accurate reading. To test the transformer from voltage, use your multimeter to measure the voltage on either terminal of the transformer. 

For example, if you want to find out how much voltage is running through a particular terminal of your AC transformer, measure it at one of the black wires and then again at one of the white wires. The reading will be higher at one of these terminals than it will be at another terminal because each wire has a different potential for carrying current.

To test the transformer from current, use your multimeter to measure the amperage on either terminal of the transformer. For example, if you want to find out how much current is running through a particular terminal of your AC transformer, measure it at one of the black wires and then again at one of the white wires. The reading will be higher at one of these terminals than it will be at another terminal because each wire has a different potential for carrying current.

What happens when a transformer goes bad?

When a transformer goes bad, it can cause major problems and interruptions in the power grid. The following causes may result in HVAC unit bad transformer symptoms:

  1. Bad Contactor - A blown transformer is typically caused by a bad contactor. The entire unit is put under a great deal of stress by a faulty contactor. Most often, a blown transformer happens when the unit can no longer sustain the stress or pressure.
  2. Wiring Problems - A short circuit caused by loose wires or cables within the transformer could cause it to burn up.
  3. Power Surge - A power surge, which is an electrical failure, can also result in transformer failure.

Therefore, you should go ahead and install a new transformer to fix the problem.

Can I replace the transformer myself? 

The question of whether you can replace a transformer yourself is a common one. It’s not as easy as it sounds. If you have the knowledge and skill, then yes, you can replace your transformer yourself.

 Caution: Unless you have the necessary knowledge and skills, it might be better to hire a professional to handle the task for you.

Looking for quality parts for your HVAC System? Look no further than our inventory! We have everything you need to keep your HVAC unit running smoothly. 

We at PartsHnC, specialize in providing the best quality HVAC parts and accessories to customers. We offer a wide range of HVAC parts, such as filters and condensers, but also carry circuit breakers and transformers from well-known manufacturers that are 100% reliable and cost-effective.

HVAC Transformer

A transformer transforms electrical energy from one alternating-current circuit to another or multiple current circuits. It is used in low-voltage devices to reduce the voltage of conventional power circuits. Transformers change voltage using electromagnetic induction. Current is generated in a secondary winding as magnetic flux lines build up and collapse with changes in electric current traveling through the primary coil.

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