Author Topic: HRV question  (Read 1808 times)

Offline nash668

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HRV question
« on: July 26, 2015, 06:07:01 PM »
I'm not to familiar with HRV's. But I did an AC for a friend and couldn't help but notice that it was connected to the Y1 on the furnace before there was any AC installed...

Any reason why? I'm assuming it's like a "free cooling" feature. Kind of like an economizer on a roof top?

Thank you!

Offline Admin

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Re: HRV question
« Reply #1 on: July 27, 2015, 07:11:04 AM »
What kind of HRV was it?  Most HRV controls don't operate on 24V so I suspect this was the interlock wiring used to synchronize the furnace fan with the HRV.  Usually it's connected to G, but they may have used Y1 to energize a different fan speed.  Does the furnace have an ECM blower?

The HRV shouldn't run during the summer months and even if they ran it during cool nights, the design of the HRV should be such that any cool air that was brought into the house would be warmed up by the warmer exhaust air leaving the house.

If you correct the interlock wiring make sure to use the 3 wire method and not the 2 wire method or it could cause the AC to start because Y is being back fed with 24V.  I attached a wiring diagram to this post.