Why would the furnace fan be tied to my master bath fan?

My furnace fan comes on with the fan in my master bath. And the vent fan when the furnace operates. Why would the furnace fan be tied to my master bath fan? I also see that the fan draws air from an outside vent. We have a smell coming out of our vents that smells like rotten hay. Never seen a setup like this. Not sure what to do...

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Answer by scott96 (113)

You have a fresh air/venting system. It's made to get fresh outside air into the house and stale air out. The smell might be from mildew in the ducts.

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Answer by thelostone (1457)

There is no reason for this besides somone did it that didn't know what they were doing. REwire them all so they are on independant cicruits like they should be.

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Answer by champaign9497 (11977)

You need to get ahold of a professional in heating and cooling that could be a very deadly situation for you and your family and if they put hay in the duct work for insulation that can cause breathing problems in humans.

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Answer by champaign9497 (11977)

You need to call in either a service tech or a contractor the furnace fan should not be hooked up to the vent fan both of those things should be isolated and on their own you also should not be having oders coming out of your vents hopefully they can get there promptly and fix this for you.

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Answer by IanValentineHvacr (26)

Furnace and fan are obviously wired together like a 3 way switch. Trace furnace fan back to original power source hand ove hand. There should either be a splice where the wire was connected or it is wired to the other side of your fan switch.

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