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Dehumidifier wiring

5.6K views 38 replies 7 participants last post by  owenfi  
#1 ·
I have a Lennox XP-20-036-230-A02 air handler. I just had a HVAC company install a Honeywell DR-65 dehumidifier, the install went well, but I noticed it will not shut off. They have been back a few times to try and figure it out, they still have not been able to. They think they may have to cut a jumper on the circuit board? Any help to figure this out would be appreciated.
 
#2 ·
Do you mean the Dehumidifier or main fan keeps running? Both? Is it actually dry in the house? What have you set the humidistat to? What is it reading? We'll need pictures of the setup. I see no reference to a jumper in the manual.

Cheers!
 
#4 · (Edited)
Thanks fir the reply!

The only thing running is the dehumidifier. Main fan is not running. The system can be turned off and the dehumidifier keeps running. I believe they said they have to find out why 24 volts is always coming out of board connection.
They think they may have to cut a humiditrol jumper on the board. I will attach a couple of pictures. (On the pics the wires come off board to a relay and than to dehumidifier).

Yes it is dry in house.
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#6 ·
Thanks for the response.

Why would the dehumidifier be running if it’s not calling for dehumidification? The Lennox board is what feeds the dehumidifier which is controlled by the Lennox iComfort S30 Ultra smart thermostat.
 
#10 ·
👍
No matter what, the board in the air handler is sending 24 volts to dehumidifier. I guess I will wait on tech to hear back from Lennox about if they should cut humiditrol jumper as per iComfort S30 manual.
 
#11 ·
I have a Lennox XP-20-036-230-A02 air handler. I just had a HVAC company install a Honeywell DR-65 dehumidifier, the install went well, but I noticed it will not shut off. They have been back a few times to try and figure it out, they still have not been able to. They think they may have to cut a jumper on the circuit board? Any help to figure this out would be appreciated.
[emoji106]
No matter what, the board in the air handler is sending 24 volts to dehumidifier. I guess I will wait on tech to hear back from Lennox about if they should cut humiditrol jumper as per iComfort S30 manual.
You gave us the outdoor unit model number. We need the indoor model number. Do you live on the coast? It's unusual to get a whole house Dehumidifier AND a variable capacity ac.

The board will continue to provide a signal as long as the thermostat is requesting it. (which you also haven't provided a model number for.)
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Cheers!
 
#12 ·
Sorry I didn’t realize I posted the outdoor unit tag. I will post the indoor air handler number. I provided the thermostat model…Lennox iComfort S30.
The air handler is a Lennox CBA38MV-042-230-6-01…So sorry for posting wrong number.
Maybe thermostat is bad
 
#18 ·
Do NOT cut anything on hr board. You will PERMANENTLY damage the board and will no longer be able to use a Dehumidifier with a the S30. (there are about a dozen models of that thermostat. That's what I'm asking about. Something like Cat # : 19V30)

The Dehumidifier requires an external field supplied relay between the Dehumidifier and the air handler. It needs to be wired right or you'll get the result you're seeing. The S30 also needs to be setup with an "auxiliary Dehumidifier".

At the price of that setup, I would expect white glove service. I initially thought the prices listed under my account were typos, it's NOT cheap.

Cheers!
 
#20 ·
Those boards that run on 24V have a transformer to supply power to that board. That same transformer may be used to power the GAS IGNITER. I would make sure before attaching any "appliance" to that 24V that the transformer can handle extra load. I would call the furnace maker if you have a GAS furnace. I have no idea how many amps yo

HOWEVER Honeywell DR-65 dehumidifier has like 25 possible attachments mentioned in the install manual (thermostats, Manual Dehumidistat and Automatic Ventilation Controls, all kinds of gadgets, manual humidistat% comfort selector, ...)

I'm confused here. You assume don't have a psychometer hookup that is supposed to activate the de-humidifier but (HOWEVER) i can't assume you don't either. You said you had professionals install it, but they didn't do it correctly and walked away and still billed you despite not finishing.

You said it's always running but didn't say if your target humidity has been effected?

Never pay service people unless they complete work they promised. Never pay them before the job.
 
#21 ·
"Follow this diagram if using TrueDRY DR65 with a powered dehumidistat such as TrueIAQ (DG115EZIAQ)." ?? is this the right diagram?

Input ratings• Electrical input voltage: 120 VAC, 60 Hz nominal• Input current: 5.2 A

Output ratings• Power transformer to R/C terminals: 24 VAC, 0.85 A
 
#25 ·
Ok, let me clarify. System was installed about 2 years ago and I had a portable dehumidifier that I got tired of dumping. So 2 weeks ago I called another company to come out and install this whole house dehumidifier. Everything seemed good until I realized that it would never shut off. The main fan on the air handler would shut off, but not the dehumidifier. The installers came back and are still trying to figure it out. Hopefully tomorrow they will figure it out. They didn’t want to cut board and are checking on what it could be. I will attach relay pic and pic of dehumidifier connection. Im trying to figure it out for myself…I think it’s in the S30 thermostat. Here are pics of board to relay, relay, and relay to dehumidifier. View attachment 659978 View attachment 659979 View attachment 659980 View attachment 659981
 
#29 ·
You do realize that your unit has a dehumidification feature? You'd only need the Dehumidifier if it's cold and you don't need the ac.

All of that is deactivated when you choose auxiliary Dehumidifier. A different set point is used for it.

Cheers!
 
#31 ·
Setting to a low airflow amount is critical to getting good dehumidification from that system. I believe it can idle down to about 20% of rated capacity but I could be wrong. You'll basically want to set that number as low as it'll allow you to. (hopefully as low as 250-300cfm.). Basically, when it's warm enough to need any ac at all, it shouldn't ever shut off.
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Cheers!
 
#34 ·
Strange. I'm pretty sure it does. At least the manuals indicate that.

Either way, you'll want to change the settings so that the ac will try to dehumidify also. It'll be more efficient at it, as long as it's not too cool out. Adjust the settings I mentioned above. You'll have to remove the auxiliary Dehumidifier option.

Cheers!
 
#37 ·
I'm running into a possibly similar situation with hardware along the same lines and have a guess as to what's going on (but no clue why on earth it would be this way, I asked about that in HVAC-Talk)

So I have an S30, with settings enabled for Aux Dehumidifier (I only have a furnace, no AC or heat pump; but I do have a Santa Fe 120H whole home dehumidifier wired inline).

It wasn't running quite right (furnace fan doesn't stay on while it runs, dehumidifier priority seems to be lowest even below "Fan On" which I always leave on) so I started investigating.

I found with with my multimeter that the DH output is "active low" that is to say:
When the S30 calls for dehumidify it goes to 0V, when it is not calling for dehumidify it is at 24V!
This was exactly BACKWARDS of what I expected.

This is not documented anywhere as far as I can find (S30 or furnace manual or wiring guides), so I think there is a chance that it is a bug in the firmware.

That said, mine is wired properly with a relay (just seems wasteful and dumb as it is though, but I could definitely be ignorant of a valid reason) so it does control properly, it's just that I need my furnace fan to stay on and it doesn't.

If yours is backwards you should observe it turning off when the dehumidify call comes, which it doesn't sound like it happening, but maybe the humidity is naturally lower? Or did you fix it some other way?
 
#38 ·
I'm running into a possibly similar situation with hardware along the same lines and have a guess as to what's going on (but no clue why on earth it would be this way, I asked about that in HVAC-Talk)

So I have an S30, with settings enabled for Aux Dehumidifier (I only have a furnace, no AC or heat pump; but I do have a Santa Fe 120H whole home dehumidifier wired inline).

It wasn't running quite right (furnace fan doesn't stay on while it runs, dehumidifier priority seems to be lowest even below "Fan On" which I always leave on) so I started investigating.

I found with with my multimeter that the DH output is "active low" that is to say:
When the S30 calls for dehumidify it goes to 0V, when it is not calling for dehumidify it is at 24V!
This was exactly BACKWARDS of what I expected.

This is not documented anywhere as far as I can find (S30 or furnace manual or wiring guides), so I think there is a chance that it is a bug in the firmware.

That said, mine is wired properly with a relay (just seems wasteful and dumb as it is though, but I could definitely be ignorant of a valid reason) so it does control properly, it's just that I need my furnace fan to stay on and it doesn't.

If yours is backwards you should observe it turning off when the dehumidify call comes, which it doesn't sound like it happening, but maybe the humidity is naturally lower? Or did you fix it some other way?
The OP hasn’t so much as logged into the site in over 2 years. You'd be best to start your own thread.