Goodman GMT-070-4 with Aprilaire 700 and Model 60 humidistat

Hello,

I have had this humidifier installed for about 9 years now and recently, due to a recommendation from an hvac guy when he was here to fix our other heater, bought the model 60 humidistat to update the system. I know people around these forums are not so keen on the automatic blower function but that is what sold me on it as I'm currently having to run not only the whole house humidifier but also a supplementary humidifer upstairs that I have to fill 3 times a day.

Anyway on to the problem. I followed the wiring diagram exactly as it is shown on page 18 of the manual ( I can scan that if that helps). It was very similar to the original unit. basically everything is the same accept I took the G wire from the thermostat and connected it to the G pot on the model 60. The Gf was a new wire I had to run to the G terminal on the furnace.

I do have an external transformer that was installed by the original tech that installed the humidifier.

The basic function, which the old humidistat did, is working fine. The unit will turn on when heat is called for and shut off when the blower is shut off. The problem is when the unit tries to turn on the blower itself. It will click very fast and the blower never turns on.

I went through the troubleshooting in the manual and it says when this happens to check the VAC across the R and C wires. I checked that and it's a constant 27 VAC. The next step is to check the VAC across the W and C and the G and C. These are also supposed to be between 22 and 30 but are not. Sometimes they are around 5 VAC and other times as high as 15VAC but I have never seen them above that.

The manual has the troubleshooting, which I have found and know why it's not working, but it does not have any information on how to resolve the issue.

Any help would be hugely appreciated. My HVAC company won't help me because I bought the unit myself which is why I'm doing the install.

Thank you for your time.

 

I took some pictures of all of this mess of wires that is in the unit but I'm not sure if it would be much of a help. I was pretty shocked at how much of a mess it was when I opened it up.

The other wierd thing is the the unit is not showing the same humidity as some of the weather stations in the house. In the picture it's showing 48% but the 2 I have sitting on the main floor both show 36% in the house. Not sure why it's more than 10% higher.

 

Remove the G and Gf wire, and wire nut them together, and see if the can comes on with the t-stat fan switch set to "ON".

 

I'll give that a try tonight. I can say that turning on the blower as it's wired now from the thermostat does work.

 

Here's the diagram from the manual that I followed

 

Ok if it is able to turn on the blower with stat but not for humidity, then I'm thinking the humiditystat maybe the issue.

 

I talked with Aprilaire tonight. After discussing the setup with them we found that the R and C connectors are connected to the external transformer. They think the reason it's not working is because the common is not common. So they have recommended I remove the transformer from the setup and connect the R and C directly to the furnace. I have the older Aprilaire 700 almond color which apparently has a transformer built in or something. They said I shouldn't need it.

Anyway, going to give that a try and will post back with the results.

Thanks !!!!

 

Well, Foiled again. I've spent the last hour trying to find the R and the C. R was easy. I've circled it in yellow in the image but there is no C on the board. Where the heck is the common? The thermostat upstairs is not connected to the common either. It's only got R, W, G, Y

 

For goodman, you will have to use the ground screw.

 

Thanks so much. The ground screw worked and the blower is now activating. Everything looks to be working but the humidifier is not starting water flow when the blower only is on. When heat is on water does flow. I wish the manual offered solutions.

 

Is the "Blower Activation" switch set to "ON"?

Honestly, I am not a big fan of running the humidifier with fan only. I've tried this once, and a lot of water was wasted, so I went with heat only call, and it kept up just fine that way.

 

Yes. The blower activation switch is on. The unit is passing all of the tests in the manual except for the celinoid is not kicking on in blower only test. The whole reason for getting this unit is due to the fact that heat only is not doing enough. I have to run a secondary 9 gallon a day Honeywell portable unit on the top floor to keep the humidity above 30%. Filling that 3 times a day is annoying when I have this whole house one. The problem is that during the day the heat does not run due to the massive number of windows we have on the back of the house. Any added humidity is better than none.

Thanks so much for the help

 

Is the Test is what you are following on page 20?

 

Yes, the test on page 20 is what I'm talking about. The test on page 19 when the heat is called works fine.

 

Also that image I posted in post 5 is wrong. That was not the wiring diagram I followed. I have the almond colored 700 which has the built in transformer so I followed the diagram I included in the last post. It's now wired exactly like that. There is no external transformer involved in the setup at all.

I do appreciate all of the help. Thank you so much.

 

So I figured out what was wrong. The guy that originally installed the humidifier took off the power plug and tied the humidifier power into the furnace safety switch for white and green but ran the black wire to the furnace 120v HUM port so the humidifer was only getting voltage when the heat was running. I ran the black wire to the black wire off the furnace safety switch and all is now working.

Thanks so much for all of the help. I could not have completed this without this site and you Jay.

 

Glad to hear you got it up and going, and thanks for the update..

Glad to help!