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Heating, Air Conditioning, Fridge, HVAC/Gas Furnace Transformer Replacement


I have a very old gas furnace. The transformer has blown. Where the furnace is so old no one has the transformer that is the original. I went to a local store and they sold me a class 2 transformer. the numbers that I got off the transformer were: 90-T40z input 120v output 24v class 2yfir 60 hz blk wth. The problem I am having is the new transformer has 4 wires that can be hooked up nd the old transformer has five wires that are hooked up and not to mention they are wrapped around screws. How can the knew transformer be hooked up properly.


Hi Tammy, You don't have to have a exact replacement as the original. Your new one is a 40VA transformer, which is the correct size. There are two types of transformers, single and duel. On the duel you can hook up 120V or 230V. The transformer you bought is for 120V input. We will have determine if your furnace is 120V. Send me the make and model number of your furnace.

Heating, Air Conditioning, Fridge, HVAC

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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