Aprilaire 400 wiring questions

Hi all, first time playing with a HVAC project, hoping to get some advice setting up my Aprilaire 400:


Is it OK to use CAT5 cable for the low voltage wires I need to run to setup the humidifier? This would be 22 or 24 awg.


According to the instructions, I need to wire the G input to G on my thermostat, not the furnace This has me a bit puzzled as my thermostat is upstairs and I had assumed was wired to G on the furnace. This is an Amana 90 (either 090_30 or 090_50) furnace.


Thanks,
Paul

 

You can use network wire to hook up your humidifier but you're going to have to double up at least two of the wires.

 

I see no mention in the instructions for minimum gauge; I have some 16 awg but it seems like overkill. Any thoughts?

 

18 gauge t-stat wire should be used.. I would not advise using the CAT5 wire for this.

Do you plan on running the fan or use the fan to add humidity when heat is not needed/running?

 

Hi Jay, thanks for the clarification. I am unsure on the fan, I don't know if I'll get enough moisture with just the furnace cycles, so I am inclined to set it up to run whenever needed. Would I need to deviate from the provided wiring diagram to get this result?

 

Does your furnace run long cycles, or are they very brief and often?

What is the make and model on the furnace?

I may not be back for the rest of the night since we have plans, but will be back for sure in the morning! (Well, later morning hours!)

Happy New Year to you too.

 

It's an Amana 90 (either 090_30 or 090_50) furnace, I would say the run cycles are fairly long and infrequent.

Happy New Year indeed!

 

That is the Series name, I need the full model # from the nameplate itself.

 

I was afraid you were going to ask that, the only info I can find on or inside the furnance is a sticker on the AC portion of the assembly, that shows model CCA24FCC.

Here are a few pictures, any advice on how to proceed is greatly appreciated.

 

The name/data plate is in the upper section of the furnace. Should have a sticker on the side with all the info.

 

Well I've learned something already! Model is GUCA045BX30, MFG# P1241601F.

Paul

 

Looked it up, and we need to use a Transformer.. Did you get one with your Humidifier?

 

Yep, 24vac transformer was included.

 

You'll wire the line side of the transformer to the HUM H and N on the furnace.

Then you wire like this.. Where it says HUM, that will be wired onto the low voltage side of the transformer.
[ATTACH=CONFIG]5070[/ATTACH]

 

OK, I think I get it, let me map out how I see the wiring going:


[TABLE="width: 500"]
[TR]
[TD]ADHC strip[/TD]
[TD]Furnace[/TD]
[/TR]
[TR]
[TD]R[/TD]
[TD]R[/TD]
[/TR]
[TR]
[TD]C[/TD]
[TD]C[/TD]
[/TR]
[TR]
[TD]ODT[/TD]
[TD]temp sensor[/TD]
[/TR]
[TR]
[TD]ODT[/TD]
[TD]temp sensor[/TD]
[/TR]
[TR]
[TD]W[/TD]
[TD]W[/TD]
[/TR]
[TR]
[TD]G[/TD]
[TD]?[/TD]
[/TR]
[TR]
[TD]H[/TD]
[TD]transformer[/TD]
[/TR]
[TR]
[TD]H[/TD]
[TD]white wire from humidifier[/TD]
[/TR]
[TR]
[TD]Gf[/TD]
[TD]G[/TD]
[/TR]
[/TABLE]


The transformer has two wires on one side (black and white) and two terminals on the other (labelled 10VA 24Vac). Are you saying the white wire goes to HUM N and black goes to HUM H on the circuit board? Then one terminal goes to the other H output on the ADHC strip, the remaining terminal goes to the yellow wire from the humidifier?

Thanks.

 

Yes, the white wire from the transformer goes to HUM N, and black to HUM H.

No need to hook up G wire at all. I don't advise running humidifier with fan only.

One side of the humidifier solenoid wire goes to H, and the other side of solenoid wire goes to the transformer.

 

Great, I'll get some furnace wire today and give it a shot tonight. Any suggestions on how to mount the transformer? Doesn't seem like a good idea to leave it dangling or resting on the bottom.

 

Mount it on the side of the furnace.. If there thread for knock out, then mount it in the knock out.. if if screw in place, then screw it to the side.

 

Thanks again for the assistance, I was able to get everything working on Thursday, and mounted the transformer on the sheetmetal used to hold the logic board. The unit is working, however I am underwhelmed by the amount of humidity it is adding to the airflow. The humidistat is mounted about 8" above the return vent but reads much higher %RH versus a number of portable hydrometers, sometimes as much as 10% too high. Putting the unit into manual mode did not make a difference, so I then removed the humidistat from the return vent so it would measure untreated (dry) air in my basement. It still reads high.

Any thoughts? I'll call Aprilaire on Monday but I'm thinking the humidistat isn't accurate.

 

8" above return vent??

Take a photos of this for me.

 

Sorry, I mashed some terminology together: the humidistat is mounted on the front of my return plenum, about 8" above the point where the bypass duct dumps in. Right now the humidistat is dangling off the front of the return with it's sensor reading the air in my basement. The display shows 48%, my hydrometer reports 33%. :|

 

Are you reading on more than one hydrometer?

Maybe your hydrometer is off?

 

Two different devices, both have similar readings. I put the Aprilaire 60 humidistat back on the return in auto mode and it has shown readings as high as 60% today. I'm definitely new to all this but it seems like I would always get higher relative humidity readings if I measure the colder return air as opposed to the recently heated air being sent up the supply? Leaving one of my hydrometers on a register reports very low humidity, in the 20's%. I'm going to talk to Aprilaire tomorrow, but I'm tempted to mount the humidistat on the supply trunk.

 

The humidity reading WILL be lower in the supply side.. When that air reaches in the room itself and "Cools" down, the humidity then rises.. so, do NOT install the humidistat in the supply it will be damaged from the heat.

The reading in the return may be a little bit higher since the air in that is cooler, and you may have a fresh air tied into your system from outside?

 

Fresh air and exhaust appear to be ducted directly in/out of the furnace via smaller pvc pipe. I spoke with Aprilaire today and am dissapointed that they couldn't offer any solid suggestions, nor do they feel there is an issue here. Regardless of what their device says, my house is still far drier than I want, I have a humidifier that could easily resolve that problem but their "logic" dictates otherwise. Even a $50 room humidifier allows me to tell it to run if that's what I want to do.

 

Do you have a temp probe? Maybe the air in the return duct is cooler, so the humidity reading will be higher in it.

 

I don't anymore, I'll dig one up and play around, maybe I can find a better location for the unit. It has been consistently reading 6-7% higher than my other humidistats. Not as bad as I first thought but it makes a big difference. I'd be a lot happier if it were reading low.

Aprilaire suggested mounting it somewhere else in the return duct, I don't really want to keep drilling holes as a guessing game.

 

An update for anyone keeping score: after a few weeks I am confident the Model 60 thermostat reads high, typically 4-7%. This wouldn't be a problem if I could set the unit to 50 or 55%, but it maxes out at 45% (which in my case means 38-41%) so my house is still too dry. The 400 works great, it is delivering water just not enough. A couple conversations with Aprilaire were very discouraging: they are confident their unit is properly calibrated and I should have plenty of moisture in my home. Apparently my three humidistats are all wrong, their unit is correct.


So my solution was to buy a humidistat that can be turned up to a higher % moisture, specifically a GeneralAire MHX3. Looking at the wiring options in the manual ( https://www.discountfurnacefilter.co...ers_Manual.pdf ), it looks like Diagram 1 for "wiring 24v bypass humidifier" would work?


I'm thinking C on the humidistat goes to the white wire from humidifier solenoid,
NO on the humidistat goes to the transformer, the other terminal on the transformer goes to the remaining humidifier solenoid wire.

 

Yes, that would work.

You will lose the adjustments with the outdoor temps. Honestly, I don't advise having it over 40%, then it just a risk of water damage some where in the home.

 

Jay, thanks again for your help, it is truly appreciated. I understand your caution however I am struggling to understand if I have too much moisture in my home. Only once have I seen any windows with condensation, it was yesterday with a high of 10* and even that was just a tiny bit of mist in one corner of a few windows on the shady side of the house. I do not want to deal with mold, but as it stands the house feels dry: skin, static, cranky animals and wife... :O

Apart from moisture on windows, any other ways to tell if there is too much moisture? Are there certain areas of the house that may be more susceptible to damage that I could keep an eye on?

Thanks!

 

Yeah cool spots on the walls in older homes, and maybe other hidden spaces. If you have heavy shades, it will build up more on those windows.