4 Answers

a transformer is to convert 120 volts of electricity into 24 volts which your thermostat runs off of the reason for the transformer is for saftey.

How Does an HVAC System Manage Energy Surges?

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  Some HVAC units will utilize what is known as a voltage regulator transformer. This transformer helps to condition the incoming voltage from any spikes that can occur in the power. You may notice these spikes when a light bulb may seem a little brighter or the power will just go off for a second or blinks. The voltage regulator transformer aids in smoothing out the spikes so it will not damage the internal circuitry used for controlling the HVAC unit.

  
  

  
  
  
  

Read more: How Do Transformers Work in HVAC Units? | eHow.com http://www.ehow.com/how-does_4564978_transformers-work-hvac-units.html#ixzz2Bgfy5nm7

To increase current flow.

There are many deference kind of transformers some to increase voltage or decrease depending on the use for.