Any HVAC experts?
 

So I have a question about my air exchanger. When we initially built the house, they told us they installed an air exchanger as these new houses are somewhat air tight. They said to be careful how much I use it as it could increase my electric bill if I keep blowing all my hot air outside and my furnace has to run more often to keep the house at a certain temperature. Anyways, years later we had a A/C unit installed and connected to the furnace. We still hadn't really used the air exchanger up to this point. I recently turned on the air exchanger while my furnace thermostat was set to off just to circulate the air in my house. I noticed that the fan on my A/C unit would run when the air exchanger was on. It was not cooling the air but it was running continuously while the air exchanger was on. Is this normal? I don't know much about these things.

Depends on a few things. First, if it is JUST an air exchanger then yes, you have to reheat the incoming air (or cool it). If it is an HRV then those units recover much of the heat (cold) so that only a portion has to be reheated or cooled.
Most exchangers now are plumbed to the furnace to give distribution throughout the house so the fan will come on for that distribution.
My HRV is installed so that it can go throughout the house or only in the basement where all my tanks and cultures are, but I have to physically change the HRV output to just the basement or to connect it to the cold air return of the furnace.

Yes if you are running the air exchanger the furnace fan will come to replace the air in the house that the exchanger is removing from the house. Air going out has to be replaced with air from your furnace it will have a fresh air outside connection that pulls in the fresh air to accomplish this. This is a typical hook up in the newer homes. :biggrin:

Depends on how it's setup, quite often if you have forced air heating the air exchanger ties into the cold air return and heating ducts of the furnace. If this is the case the furnace fan needs needs to run with the exchanger fan. I'm not sure about the AC fan, central air units have a fan on the unit placed outside and the coil is just placed in the furnace and uses the furnace fan. So which fan is on exactly?

But should my air conitioning unit fan come on as well. I am okay with the furnace fan being on. Would that mean I cannot run my air exchanger in winter as my air conditioning unit would be covered and I am assuming you shouldn't have the fan running under the cover.

I don't think the fan on the outdoor A/C condensing unit should be running...

If it's running, it probably means the compressor is running as well, which means your A/C is effectively ON.

That is what I thought, but when I went to the registers it was blowing warm air not cold air and the thermostat was set to off. As soon as I turned off the air exchanger the fan stopped turning on the a/c unit. Since then I have had the a/c on and it blows cold air just fine. I am at a loss. Maybe I will go turn the thermostat to heat and see if the air exchanger still turns on the a/c unit.

That seems really weird to me - can you call the place that did the installation?

Unfortunately, they were not that great to deal with in the first place and it was so many years ago they wouldn't do it for free now. I just talked to an electrician friend and he suggested that if everything else works fine, he would just turn off the breaker for the air conditioner in the winter and not worry about it although it did sound to him as if they wired something wrong.

I had something like this in my last house. When we turned on the circulating fan the AC compressor would start. I was told it had to do with the relays for the fans and they would need to be changed. I never did, I just tuned the breaker of for the AC off.