Wednesday, March 12, 2014

Beginner Moving Humidistat For Generalaire Humidifier Model 1042lh



Hi,
I bought a house recently and have been trying to learn more about the humidifier that was installed. I have a Generalaire bypass humidifier Model 1042LH. House was built in 2004 and is 3000 sq ft.
The filter was pretty rusty and the drain pain was pretty dirty so I bought a few replacement filters and replaced the drain pan.
Everything seems to be working fine but I am a complete novice when it comes to HVAC stuff. Humidity in the house is around 30% and no moisture on windows except for two large ones with hunter douglas architella duette (honeycomb) blinds that get frost even if I leave a small gap at the bottom. I'm trying to see if the frost/condensation gets better if I raise them a bit more but it seems like this is a common problem with insulated blinds. Temperatures at night here get in the teens.
Anyways, I was reading the instructions and noticed that it said to not install the humidistat on the warm air vent, only the return. I don't remember it mentioning why this was bad.
I noticed that mine is installed on the warm air vent and was wondering if this is a big issue. If it is, how can I fix it? Hopefully it is straightforward and something a beginner can do.
Thanks
Here are some pictures (click to enlarge).

The humidistat should always be mounted on the return duct BEFORE the humidifier. This way it can get an accurate reading as to how much moisture is in the air coming back from the conditioned space. The whole point of the h-stat is to determine if the house has enough moisture in the air or if it needs more and it can't accurately do that when mounted downstream from the humidifier. All you would need to do is pull it out from where it's currently mounted, measure and cut a new hole, re-mount it and re-connect the wiring (which is only 2 wires), and patch over the hole on the supply. It's an easy fix but may be slightly more involved since all of your duct is insulated.

thanks.
stupid question: what tool do I use to cut out the sheet metal when I mount it on the return duct?
is an acceptable location of the humidstat in the same location as the current one but on the return vent? see picture one. I was thinking to just move it across to the correct vent (mounted under the vent running across the ceiling).

You would use aviation snips... tracing out the hole for the h-stat and then punching a hole in the center with a hammer and flathead screwdriver is the easiest way to get started. Another good tip is that it's always easier to start a little small and have to make the hole bigger. Once you make the hole too big it's MUCH more difficult to fix. The location you chose to use would work just fine, I've seen several mounted in that same location.

ok thanks.
two more stupid questions:
what should I use to patch up the other hole?
If I turn off the circuit breaker to the furnace will that be sufficient to protect myself when reconnecting the wires?

If you have any sheet metal laying around you can screw in a patch, and seal it with foil tape.
Yes, turn off the power on the system, and make notes of how the wires were hooked up on the humidistat.
When it's on the supply side, the air is going to be dryer and it will have a false reading.
It is normal for frost on a window behind blinds. I have the same thing in our home.

Hey there. Seems like you all know what you are talking about. Have the GeneralAire 1042LH and it was installed by a professional. I changed the filter last week as I know this is to be done yearly. I have not had any water come down through the filter in to the drain hose since I changed it. It is starting to get cold here in MI and I am noticing more static.
So, I took the water lead coming in to the selenoid off and there is water getting to it. There is no water coming out after the selenoid to drain in to the filter. I turned the humistat control to ON yesterday and still nothing in the filter. Is it the selenoid?

Originally Posted by Rjgator
Hey there. Seems like you all know what you are talking about. Have the GeneralAire 1042LH and it was installed by a professional. I changed the filter last week as I know this is to be done yearly. I have not had any water come down through the filter in to the drain hose since I changed it. It is starting to get cold here in MI and I am noticing more static.
So, I took the water lead coming in to the selenoid off and there is water getting to it. There is no water coming out after the selenoid to drain in to the filter. I turned the humistat control to ON yesterday and still nothing in the filter. Is it the selenoid?
Please start a new post, you are going to get other confused with you in the mix.
Did you check for power to the valve?
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