Hello Folks:

I had a Carrier Heat Pump (Model 25HNA6) with variable speed blower (Model FE4A) installed this past March. A Carrier Infinity Thermostat / Controller was also installed at the same time (SYSTXCCUID01-A). The existing Aprilaire 760 humidifier was kept because at the time installation, it was working fine.

However, the humidifier is no longer working – probably because it was wired incorrectly. The wiring diagram for the humidifier, as installed into the new Carrier system, is below.



Carrier_Hum_Terminal -------> Aprilaire Humidistat -------->Brown Wire on Apriliaire


Carrier_Com_Terminal -------------------------------> Brown Wire on Apriliaire

Aprilaire_Power_plug ----------------------> 120 volt outlet on wall

Note that the 120 volt outlet is just a standard wall outlet near the Carrier unit. It is not part of the Carrier system.

One curious thing is that there is ALWAYS 24 volts across the Carrier Com and Hum terminals. This is true even if turn the Infinity to “off”, i.e., no heating or cooling.

Questions:
Thanks,

RW

 

I will have to do some reading on this... I have not done anything with Carrier's Infinty stat.

I;ll post back later tonight after supper.

 

Looks like the dealer has to read the install manual.

On page 5 of the furnace install manual. it says that a relay must be used on your powered humidifier.

The Aprilaire Humidistat is NOT needed on this, the Infinity t-stat takes care of this for you.

 

I know.

This has (apparently) been the most incompetent install job ever done. The main issue was that the salesman stated that there would be no problem installing new Puron refigerant lines between the joists and the removable ceiling tiles in my basement. WRONG.

The installers came out and went "Oh sh**. Not enough room between the ceiling and joists. We will have to rip down your wall" (See attached picture).

Then they had to come back a few days later when the auxillary heating started tripping my 100 amp double pole breaker (never given an explanation on this one, but the problem hasn't come back).

Then they had to come back just after Memorial Day when the unit shut down and wouldn't cool (overcharged with Puron). This one was really great as the unit failed in the middle of a Memorial Day party with ~ 50 guests and temperatures in the mid-90's.... I ended up with one MAD wife !

Now this.

I say it all rests with the salesman who incorrectly scoped out the job. This put the installers behind the eight ball as they lost ~ 4 hrs with taking down the wall and running new refigerant lines. The main installer was at my house from 9 AM to 10 PM. He took only a 10 minute lunch break. The bottom line is that he had to rush to finish things, and when you rush you have errors.

To say I am mad is beyond belief.....

Thanks again,

RW

 

Yikes...

Do you want me to help you wire up the humidfier right? I'd be happy to go over what you need to do make it right, or you plan on calling the dealer back?

 

The answer is yes to both questions. I am calling the dealer back (just faxed a description of the problem to them).

And I also want to know how to do it - just so that I know what the dealer is doing when they arrive.

The main thing that is confusing me is why is there always 24 volts across the HUM and COM terminals. Shouldn't this cycle with the demand for humidity ?

Thanks,

RW

PS - I am leaving to go out of town in a couple of hours on a business trip (I'm a mechanical engineer). I will be back late Thursday night, and the dealer is supposed to come out on Friday. So my responses over the next few days may be sporadic.

My background is in heat transfer and fluid mechanics(nuclear power and the paper industry). So I have some novice familiarity with HVAC, but I am by no means an expert. Before I posted my problem description, I searched through a number of the existing posts. I learned a lot by reading your posts to other people's issues.

Your continued comments and suggestions are most helpful !!

 

The brown wire from the humidifier is also 24 volts.. so you are reading 24 volts from the humidifier itself! HUM on the furnace is also 24 volts!

I am suprised that is hasn't' burnt/short out the transformer on the humidifier itself or the board since you got power going to each other!

 

Figured give you an ideal how it should of been done.

 

Jay:

Thanks for the information.

I suspect that the Aprilaire is fried. I kept the 120 volts plugged in, and then disconnected all the humidistat, furnance, and humidifier wires. Nothing happens when I connect the two brown wires on the Aprilaire. This indicates to me that that Aprilaire is now fried.

Also, with the HUM and COM wires are now separate and disconnected from each other. However, they always show 24 volts no matter what the humiditly control setting is on the Infinity. In fact, the voltage across these two terminals is 24 volts even with the heating and cooling both turned off. Shouldn't the voltage across the HUM and COM terminals only equal 24 volts when there is a demand for humidity ?

Thanks,

RW

 

Humm.. Yeah, it should 0 volt when there is no call.. Sounds like that may be fried/contacts welded together.

 

I have the same problem but mine is wired differently.

Here's my setup.

humidistat------>humidifier (760)------>model 50 relay

Humidistat------>model 50 relay

relay -----> furnace com lead.

Humidifier(120v)-------regular outlet.


Questions:

Is this the correct wiring?

Does the wire need to be stripped to connect to the relay from furnace?

What's the HUM terminal in the furnace for?

BTW, I have a Carrier 92 Comfort Series.

Thanks in advance.

 

What relay are we talking about? The A50 relay?

 

it's GA50 from generalaire.

 

Ok, we have 3 wires tied to the GA50 relay?

if so, that is not correct.

 

No 2 wires and a metal u shaped. looks like this.

24 volt current sensing relay general aire GA50 - eBay (item 120332681883 end time Dec-11-08 17:14:36 PST)

 

Ok, I am having a hard time "reading" this.. are you able to draw or take a photo of your setup?

 

Ok, let me give it another try.

The ga50 sensing relay comes with 2 wires on one end and a metal bracket on the other end. The manual says to connect it in a series with the humidistat and the humidifier.

ga50 Relay ----> Humidistat ----> Humidifier -----> ga50 Relay


then attach (with a wire) the metal bracket to the com lead of the furnace.

It doesn't seem to work since the humidifier doesn't turn on when blower starts.

My furnace also has a HUM terminal, is this where I attach the metal bracket? I followed this steps. (powered 760)

http://www.gogeisel.com/geiselonline...stallation.pdf


Thanks again in advance.

 

Is it the white wire coming off the blower motor? Other than that, it's wired up right.


Stay away from that with your humidifier.