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Old 05-16-2010, 09:05 PM   #1
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When running furnace on fan only.....


If I have my thermostat to "off", but fan to "on", is my air exchanger and humidifier still running, or do they only run when the thermostat is set to heat or cool?

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Old 05-17-2010, 06:55 AM   #2
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When running furnace on fan only.....


Depends on how its wired up.

It could be wired up that they are both on. Or just one, or neither.

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Old 05-17-2010, 07:20 AM   #3
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When running furnace on fan only.....


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Originally Posted by beenthere View Post
Depends on how its wired up.

It could be wired up that they are both on. Or just one, or neither.
Ok. But generally, how do I know when my air exchanger or humidifier is actually on and working? Is it safe to assume that if the intake vents in the rooms are sucking in air, that my air exchanger is working?
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Old 05-17-2010, 07:24 AM   #4
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When running furnace on fan only.....


Turn fan on. Go to exchanger, and see if its running. Do same with humidifier.

More then one system has been wired/set up incorrectly.

What controls do you have. Some automatic ones won't run the humidifier, after it gets up to X temp. others will.
Air exchangers should generally run winter and summer. But some are set up not to. Because the summer humidity is too high.
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Old 05-17-2010, 07:33 AM   #5
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When running furnace on fan only.....


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Originally Posted by beenthere View Post
Turn fan on. Go to exchanger, and see if its running. Do same with humidifier.

More then one system has been wired/set up incorrectly.

What controls do you have. Some automatic ones won't run the humidifier, after it gets up to X temp. others will.
Air exchangers should generally run winter and summer. But some are set up not to. Because the summer humidity is too high.
I have done that, but there are no lights on the exchanger, or humidifier to indicate that anything is on. I do see it vibrating and the hoses moving, but that just could be from the vibrations of the furnace. There are clear tubes, whch I assume are for water or condensation drainage, but I never see any water in them. Sorry for the stupid questions, but it's my first house with this type of equipment, and I really don't know too much about it.

The controls I have on the thermostat are "heat", "cool", and "off", and of course temperature settings for up and down. It's not programmable (to my knowledge).
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Old 05-17-2010, 07:48 AM   #6
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When running furnace on fan only.....


With the fan switch set to on at the thermostat.
Removed the cover panel for the exchanger. Depress the safety switch, see if it runs. Keep fingers clear of all moving parts.

Do same with humidifier. And look for water to run. Your humidifier may not work at all.


You may want a tech to come out and check if everything is working the way it should.
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Old 12-23-2010, 05:50 AM   #7
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When running furnace on fan only.....


I don't see a safety switch, and there are no moving parts inside. Just a filter and 4 air intake and exhaust holes. There are 2 round plates which appear to seal 2 of the holes. They only open when I set my humidity control to a setting lower than the current indoor humidity. I'm assuming when these plates are closed, the exchanger is not running? But that would mean that the exchanger would not be running in the summer, and only in the winter when I need a humidity reading lower than what the house is currently set to.
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Old 12-23-2010, 06:08 AM   #8
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When running furnace on fan only.....


In the summer. You set the humidity control higher. To maybe 50%, so that it doesn't bring in high humidity outdoor air, when your home already has too much humidity in it.
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Old 12-23-2010, 06:24 AM   #9
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When running furnace on fan only.....


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Originally Posted by beenthere View Post
In the summer. You set the humidity control higher. To maybe 50%, so that it doesn't bring in high humidity outdoor air, when your home already has too much humidity in it.
Exactly, but when I set it higher, the plates in the exchanger seal the holes, which means my exchanger is not exchanging air. Same thing in winter.
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Old 12-23-2010, 07:24 PM   #10
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When running furnace on fan only.....


You don't want it to run 24/7. You only ant it to run when the humidity is acceptable in the house.

You could get a Honeywell IAQ thermostat. And let the IAQ thermostat control it. The IAQ can be set to run it to meet fresh air standards. And not run it when not needed.
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Old 12-23-2010, 07:58 PM   #11
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When running furnace on fan only.....


What is the brand name and model of your exchanger. Post a pic of it. Should only have 1 damper and that only works when it defrosts itself.

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