Wiring my Generalaire GFX3 humidistat, possibly to nest E ?

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Old 02-03-19, 07:43 AM
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Wiring my Generalaire GFX3 humidistat, possibly to nest E ?

Hi,

I am trying to wire a new humidistat to my humidifier, its a Generalaire GFX3, there are only 6 connections to make, 2 are an outside temp sensor, those are done, 2 are labelled HUM1 and HUM2, which are connected to the water control solenoid yellow wires, then finally 2 more for 24v power, those are connected to a 24v transformer plugged into the wall. I have yet to prove if the humidifier is working correctly, as I have no errors reported on the screen, but no action from the humidifier either, there is no water flow through the solenoid at the moment, I also have a nest E, and wondered if it would be easier to wire it to that and the furnace?

thanks in advance for any suggestions!

Bugeyedbrit
 
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Old 02-03-19, 10:23 AM
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Your wiring is identical to my setup.

For what it's worth, I recently had an HVAC guy come out to debug my humidifier. He said the outside temperature sensor was bad which prevented the humidifier from operating. I did not have him replace it because I decided to figure out how to use my Nest to control the humidity. I think he intended to replace the outside sensor and the manual humidistat control because they come together in a replacement kit.

So, this may be the problem you have.

Now, regarding the solenoid. I was able to test the solenoid by disconnecting the yellow wires and touching them to the 24VAC power connections on the humidistat. Doing this energized my solenoid. You could consider doing that to test the solenoid. If the solenoid is bad, it's easy to find a good replacement at a fraction of the cost you will be charged by an HVAC company.

By the way, on my setup, power is only supplied to the humidistat when the blower is running. So, if you want to do the solenoid test I described, you have to be sure you actually have power available at the humidistat.
 
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Old 02-03-19, 10:32 AM
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Welcome to the forums.

You either have the nest control the humidifier OR you use a standalone humidistat. Not both.
In order to help you with your wiring..... you'd need to post the humidifier model.

The two yellow solenoid wires only go to the H terminals directly..... if the humidifier plugs into 120v.
 
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Old 02-03-19, 10:46 AM
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Hi,

Thanks for the replies, the humidifier was/is a Honeywell he240, but I already replaced the original solenoid with a new one as the previous one had already died, I also removed the sail/air pressure switch as again, I was under the impression the this humidistat didn't need it?

I have read I can use the Nest to control it, connecting 1 side of the solenoid to the C terminal on my furnace (the C terminal is not needed for the Nest to function at the moment), and the other to the * terminal on the Nest, is that feasible?


thanks
 
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Old 02-03-19, 11:21 AM
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That humidistat needs switched 24vAC to it. That switched power allows the humidifier to only run when the furnace is heating. So you need to decide how you are going to switch the humidifier on. You may need to keep the sail switch. This is one diagram you can use.... out of the humid stat instructions.

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Your wiring description is correct for the nest. I usually make sure there is a C connection when I run an accessory off the * line. I'm guessing the nest E has programming for a humidifier.
 
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Old 02-03-19, 11:42 AM
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So would that mean re adding the sail switch on one side of the solenoid then up to the humidistat, then back down to the other side of the solenoid?
 
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Old 02-03-19, 12:40 PM
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The following may help: https://www.doityourself.com/forum/h...umidifier.html

Now, I am concerned because there was some mention in that discussion of wiring to the W line on the Next. Check the following thread out for more details. A guy wired to the W line and blew a fuse. He presents two wiring diagrams in the thread. I believe the first one is correct but he ended up going with the second diagram and ran into trouble. It's a short thread and worth reading.

https://www.thermostatforums.com/sho...00M-Humidifier
 
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Old 02-03-19, 01:38 PM
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Those seem to be for Nest applications, rather than Nest E, I just tried the wiring this:

Solenoid - *ob terminal and other side of solenoid to C terminal on the furnace, the Nest sees the new equipment as heat pump or cooling stage 2 or heating stage 2, not an actual Humidifier! I guess I am not getting the Nest E to control the humdifier, I may have to add back the sail switch?
 
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Old 02-03-19, 01:53 PM
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That link is not really helpful and this is not a aprilaire 600.

If you are going to use the nest...... say so now. Otherwise you need to follow the diagram like this. Somehow the 24vac needs to be switched by air movement. The diagram represents using the pressure switch in the 240. If you are wiring directly to the solenoid wires on the 240 then you need to use your sail switch where the red X is.

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Old 02-03-19, 02:00 PM
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I just looked it up..... apparently the nest E does not support a humidifier. It's a scaled down inexpensive thermostat. You'd need a nest 3 or 4.
 
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Old 02-03-19, 02:41 PM
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yep, just figured this bit out....maybe I'll re install the sail switch.

thanks anyway!
 
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Old 02-11-19, 05:51 PM
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Ok, so I just installed a Nest 3, and still have no real output from the Humidifier (I wired the solenoid to the * terminal on the nest and the C terminal on the furnace) I am a little confused, as it should now be working?

thanks

Bugeyedbrit
 
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Old 02-11-19, 06:11 PM
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When you did the nest setup. It should show the * as active and ask you how you want to use it. You need to set it for humidify with heat.
 
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Old 02-11-19, 06:51 PM
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I did that, and the Nest does see the wiring as a humidifier, but I still see no flow of water through the solenoid, I take it there is no issue with polarity as its only 24v ac from the furnace?
 
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Old 02-13-19, 06:09 PM
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I obtained a relay switch - (emerson 20-290q) and wired the solenoid to the 2 and 4 terminals, then connected the * terminal on the Nest to terminal 1 and the C terminal on the furnace to terminal 3......And bupkis, still no water flow, what am I doing wrong?
 
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Old 02-18-19, 05:40 AM
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Have you tested the solenoid by applying 24 vac directly? AC has no polarity.
 
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Old 02-18-19, 08:06 AM
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the solenoid is brand new, I hadn't thought to check if its functioning! Will try that.

thanks
 
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