Thread: downstairs bathroom fan tied to upstairs furnace

right at this very moment I am in a house that is two stories. I turn on the bathroom exhaust fan downstairs and hear a loud click. I of course I am in the home by myself. I finally traced it to what I believe is the furnace upstairs everytime I turn on the fan the furnace fan appears to turn on anybody have any ideas?

Originally Posted by cory nystul

right at this very moment I am in a house that is two stories. I turn on the bathroom exhaust fan downstairs and hear a loud click. I of course I am in the home by myself. I finally traced it to what I believe is the furnace upstairs everytime I turn on the fan the furnace fan appears to turn on anybody have any ideas?

That is so unlikely, I suggest you check it again (and again) before you write it up.

......could you be dealing with a remotely located exhaust fan?.......Greg

In some jurisdictions it's a requirement that a central exhaust fan is installed. (Example the province of Ontario) Short of that it is also not uncommon to encounter exhaust fans connected to serve the same purpose, but never connected to the furnace fan.

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In some jurisdictions it's a requirement that a central exhaust fan is installed. (Example the province of Ontario) Short of that it is also not uncommon to encounter exhaust fans connected to serve the same purpose, but never connected to the furnace fan.

Originally Posted by cory nystul

right at this very moment I am in a house that is two stories. I turn on the bathroom exhaust fan downstairs and hear a loud click. I of course I am in the home by myself. I finally traced it to what I believe is the furnace upstairs everytime I turn on the fan the furnace fan appears to turn on anybody have any ideas?

Someone tell me what the implication is - additional air movement and ventilation for the home?
It is common in our area with newer homes /crawlspaces to have the main bathroom fan interconnected with the furnace air mover because it is part of the whole house ventilation system which also services he crawlspace.
That being said it is usually activated by the humidistat
If Im going to make a call there has to be a legitimate implication first

To follow up, Supposedly the clicking i hear (clicking not heard in the bathroom) supposedly is because the bathroom fan was loose.

But hey keep in mind I found that the waste line on toilet in the crawlspace of the same house was leaking and the handyman that is "making repairs" says its from the tank sweating. I will follow up when i get to do the re-inspect.

Thanks for the follow up

Follow up to the follow up.

I re-inspected the house today and had my wife come along to trace down the clicking and possible connection to the furnace fan.

I found that the downstairs powder bathroom exhaust fan does in fact turn on the furnace fan, which is located upstairs. I am unable to see if the connected or just the wiring.

The clicking was coming from the box pictured. And yes i did notice the knockout with out a collar/bushing.
DSCN2479.jpgDSCN2480.jpg

As a side note the handyman that "made repairs" stilll claims that the clicking was coming from a loose exhaust fan that he re secured.

Cory,

The clicking is from that contactor (relay) clicking in and out.

None of the grounds are grounded, some are cut off - and, no, that ground under the screw does not count as being grounded either.

Final Update to anybody that is interested,

After begging and pleading and the sale almost falling apart i was finally able to get an HVAC to look into the furnace fan that is for sure connected to the downstairs bathroom exhaust fan.

The HVAC, whom is a part of the company that installed the system, claims that they build the homes so tight that they were worried about a negative pressure when the bathroom fan is turned on so they tied the fan into the furnace wiring.

I must admit I don't believe it. Why would you tie only 1 of 3 fans into furnace if you were truly worried.

I am not sure what else I can do, to improve this situation.

Cory,

I am trying to grasp the HVAC technicians thinking, which adds to your doubts that he understands what he is doing, or, more importantly, what he is NOT doing:

To exhaust that one bathroom, instead of exhausting the air with an exhaust fan, he runs a duct to the furnace and turns that fan on to recirculate that bathroom air throughout the house instead of actually exhausting that air?

First, that air is required to be exhausted. Second, that air is required to be exhausted to the outdoors - not the indoors, and not even in a manner in which it could easily be brought back indoors.

Lastly, he is sucking all the moisture from that bathroom into the ductwork? Bath fans are frequently referred to as 'fart fans' but in reality they are not there for odors, they are there for the moisture created in the bathroom.

As far as i can tell the ducting is separate, but hidden in the ceilings, so....

I am still not sure how tying the electiral from one bathroom fan, but not the other 2, into the furnace fan would alleviate a possible negative pressure.