Failed current sensing relay on Arpilaire 400A

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Old 11-25-08, 07:51 PM
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Failed current sensing relay on Arpilaire 400A

The sensing relay has failed and is always "on". After looking at the current wiring I had a few questions. Here's how it is wired:

Furnace: Trane XV90

--The continuous 24v is supplied from the HUM-N lug on the furnace board to R-C on the controller

--The sensing relay switches power from HUM-N to W/G-Cf on the controller

--H wires on the controller are connected directly to the humidifier.

While this worked properly (when the sensing relay was working), this does not match any of the wiring configurations shown in the 400A/digital controller manual. Is this config ok?

Can I get rid of the sensing relay? Is the EAC-N lug (just below the HUM-N lug on the furnace board) an adequate switched 24v source with the fan that I can use instead of the sensing relay? I cannot find a good source of info on the HUM-N and EAC-N board connections.

If I need to buy another sensing relay, where can I find one? What kind of store sells these? (Home Depot, HVAC supply place?)

Thanks.
 
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Old 11-26-08, 07:18 AM
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You would not need the the relay on your XV90.

Is there a transformer being used?

The HUM wire on the XV90 is 120 volts, and we need ti get a transformer in place.

I will post back when I hear that you do have a transformer.
 
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Old 11-26-08, 07:57 PM
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Originally Posted by Jay11J View Post
You would not need the the relay on your XV90.

Is there a transformer being used?

The HUM wire on the XV90 is 120 volts, and we need ti get a transformer in place.

I will post back when I hear that you do have a transformer.
There is no transformer as it is connected to 24v now via the HUM-N terminal.

I guarantee you that the HUM-N terminal is 24v--I measured it personally with a voltmeter (~26v), and the humidifier has been connected to it and working since its (professional) installation more than a year ago. I have the transformer that came with the humidifier--it was never used as it was not needed.

I suspect that the EAC-N is also 24v--it sits directly below the HUM-N terminal (I did not measure that one yet). Both terminals are bare metal, unprotected male end for a spade connector. Would they leave 120v metal post in such an exposed way--someone would electrocute themselves. Isn't everything on that furnace board 24v? (This is the same board that the thermostat and control wires are housed on.)

Is the EAC only hot when the fan is blowing?

(I won't have any time to look into this any further until Friday--I'm on the hook to prepare the turkey feast tomorrow.)

Thanks.
 
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Old 11-26-08, 08:17 PM
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What is the model # of the furnace, and age?

I have the XV90 in my own home, and the HUM is 120volts.

we'll be in touch on Friday again.
 
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Old 11-27-08, 06:27 AM
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Originally Posted by Jay11J View Post
What is the model # of the furnace, and age?

I have the XV90 in my own home, and the HUM is 120volts.

we'll be in touch on Friday again.
Where do I find the model #? I looked a couple of days ago and could not find it.
 
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Old 11-27-08, 07:39 AM
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Take the top cover off (burner area), and on the right there is a silver sticker with model # and other info.

The sticker may be hard to see since some time is some what covered by the burner box.
 
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Old 11-28-08, 03:00 PM
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Originally Posted by Jay11J View Post
Take the top cover off (burner area), and on the right there is a silver sticker with model # and other info.

The sticker may be hard to see since some time is some what covered by the burner box.
Model number:TUY100R9V4W6
Manuf. Date: 5/07
Install: 7/07
This is a two-staged, variable speed blower model.

I just checked the EAC-N terminal: 28v and hot all the time like the HUM-N terminal. Hmmmm. (I'm measuring between these "-N" terminals and the BK screw-down connection--how it is wired now using HUM-N) BK is the always hot 24v source? Hmmmm. I think I'm seeing pattern here . . .

After some Google searching, it looks like the EAC N and HUM N are the "N"eutral sides and there are separate Hot connections EAC and HUM (likely what you are saying is the 120v terminals).
http://www.white-rodgers.com/wrdhom/...pg0268_270.pdf

So is there a switched 24v hot side terminal I can tap into for the W/G-Cf on the humidifier controller so I can get rid of the sensing relay? (that is the recommended connection for the Aprilaire 400.)I would like it to work during any heat stage and when the fan is turned on at the thermostat. (That's how it works now when the sensing relay works.)

After looking at the Aprilaire 400 manual again, it looks like it expects the HUM and EAC terminals to be switched "to determine furnace operation" in the first configuration. In another configuration it looks like I could use the Common/G connections for the W/G-Cf wires and accomplish exactly what I want to do (and get rid of the sensing relay?). Might this work or am I going down the wrong path?

Thanks.
 
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Old 11-28-08, 03:54 PM
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Originally Posted by jamitt View Post
I just checked the EAC-N terminal: 28v and hot all the time like the HUM-N terminal. BK is the always hot 24v source?.
BK is used for control the blower speed..


Photo below is mine.. behind this cover (Turn power OFF), there a wire taped "HUM" on it.. A knock out to mount the transformer to as seen below.


This how it should be wired if you have a transformer. Let me knwo if you do have a transformer or not.
 
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Old 11-28-08, 07:02 PM
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Originally Posted by Jay11J View Post
BK is used for control the blower speed..


Photo below is mine.. behind this cover (Turn power OFF), there a wire taped "HUM" on it.. A knock out to mount the transformer to as seen below.


This how it should be wired if you have a transformer. Let me knwo if you do have a transformer or not.
Yes, I have a transformer but it is not installed. It came with the humidifier.
 
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Old 11-28-08, 07:36 PM
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Originally Posted by jamitt View Post
Yes, I have a transformer but it is not installed. It came with the humidifier.
Ok, install the transformer as shown on my photo. Wire that to the HUM wire in the box, and wire the neutral side to the house hold neutral wire coming in to the box.

Wire the transformer to W/G and Cf at the humidistat.

Then wire R and C to the board's R and B (Not BK)
 
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Old 11-29-08, 07:26 AM
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Originally Posted by Jay11J View Post
Ok, install the transformer as shown on my photo. Wire that to the HUM wire in the box, and wire the neutral side to the house hold neutral wire coming in to the box.

Wire the transformer to W/G and Cf at the humidistat.

Then wire R and C to the board's R and B (Not BK)
With all due respect, this is counter to the Aprilaire manual. They want the transformer to provide continuous power to the R/C terminals and a switched source to the W/G and Cf terminals. See link http://www.google.com/url?sa=t&sourc...cNeRbpqLgPXzBw
Start on page 13.

I'm so confused . . .
 
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Old 11-29-08, 07:35 AM
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Originally Posted by jamitt View Post
They want the transformer to provide continuous power to the R/C terminals and a switched source to the W/G and Cf terminals..
Yes, I am aware of how Apilraire wants it wired up, but Trane's HUM is a 120 volts switched source, and R and B on the board is the 24 volts continuous power..

So it's wired another way around as what the manual calls for.
 
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Old 11-29-08, 02:52 PM
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Originally Posted by Jay11J View Post
Yes, I am aware of how Apilraire wants it wired up, but Trane's HUM is a 120 volts switched source, and R and B on the board is the 24 volts continuous power..

So it's wired another way around as what the manual calls for.
OK, thanks. I'll give it a try . . .
 
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Old 11-30-08, 03:35 PM
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Originally Posted by jamitt View Post
OK, thanks. I'll give it a try . . .
Any update for me? The way I suggest to be wired is done by many others here asking for help had no issues, and that how Trane install manual shows to install the humidifier. (made by aprilaire)
 
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Old 11-30-08, 07:36 PM
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Originally Posted by Jay11J View Post
Any update for me? The way I suggest to be wired is done by many others here asking for help had no issues, and that how Trane install manual shows to install the humidifier. (made by aprilaire)
I ran out of time this weekend--won't get to it until later in the week as I'm traveling . . .

Thanks.
 
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Old 11-30-08, 07:41 PM
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Have a safe trip and will be here if you have any questions.
 
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Old 12-06-08, 08:00 PM
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Thermostat Manual

Jamitt,

Thanks for that link to the Aprilaire Thermostat manual. If only I'd seen that before blowing up my first t-stat, it would have saved me some time, headaches and $$...

Why can't manufacturers give you all the information you need instead of writing cryptic instructions?!
 
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Old 12-08-08, 04:55 PM
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Originally Posted by Kevin1158 View Post
Jamitt,

Thanks for that link to the Aprilaire Thermostat manual. If only I'd seen that before blowing up my first t-stat, it would have saved me some time, headaches and $$...

Why can't manufacturers give you all the information you need instead of writing cryptic instructions?!
That manual came with my Aprilaire. If yours was professionally installed, the installer may not have left it with you.

That section of aprilaire's website has all their manuals--it is the professional installers' section.
 
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Old 12-08-08, 05:07 PM
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Originally Posted by Jay11J View Post
Any update for me? The way I suggest to be wired is done by many others here asking for help had no issues, and that how Trane install manual shows to install the humidifier. (made by aprilaire)
I'm back and had time to "play" with it this weekend and I'm still not happy with the results.

Installing as you suggest allows the humidifier to only run while heat is on--I also want it to run when the fan is "on" as set by the thermostat (need to do this to keep the humidity up during dryer times).

Then I rewired it to use the G and C terminals--that had the opposite effect--it only runs when the thermostat is set to fan "on" and not during heat demand (if fan is set to off).

Now I know why the installer used a sensing relay on one of the fan leads.

So going back to my original problem. The sensing relay failed. Can I accomplish my desired effect (humidifier on during heat and when fan is "on) without the sensing relay?

Thanks again for your help.
 
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Old 12-08-08, 09:36 PM
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Ok, instead of using the HUM wire for the transfomer now wire it to EAC instead.

I've ran mine in the past on EAC, I was not happy with the results, a lot more water was wasted to provide humidity.. The humidifier work best with hot air going over it.

I run mine on heat only and I am not wasting water that the non heated air is not adding the humidity into the air.
 
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Old 12-09-08, 05:16 PM
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Originally Posted by Jay11J View Post
Ok, instead of using the HUM wire for the transfomer now wire it to EAC instead.

I've ran mine in the past on EAC, I was not happy with the results, a lot more water was wasted to provide humidity.. The humidifier work best with hot air going over it.

I run mine on heat only and I am not wasting water that the non heated air is not adding the humidity into the air.
Ahh, ok. EAC is electronic air cleaner I think--that makes sense.

Thanks.
 
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Old 12-12-08, 05:29 PM
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Originally Posted by Jay11J View Post
Ok, instead of using the HUM wire for the transfomer now wire it to EAC instead.

I've ran mine in the past on EAC, I was not happy with the results, a lot more water was wasted to provide humidity.. The humidifier work best with hot air going over it.

I run mine on heat only and I am not wasting water that the non heated air is not adding the humidity into the air.
Ok, it is finally working like I want. I used the EAC connection for the transformer and this is working great! BTW, the sensing relay turns out was on the same EAC wire!

As for running the humidifier with fan only (no heat), there is no waste of water with the Aprilaire 400 as it is an on-demand humidifier that requires no drain, so all water that enters it is used. It is connected to hot water--it works great with fan only and does raise the humidity higher than during heat only, during very dry conditions.

Thanks again for you help and putting up with my ignorance.
 
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Old 12-12-08, 08:30 PM
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Not a problem helping you out..

I wasn't aware you had the 400, and overall, how do you like it? I've had a few people come back here saying the pad is not all the way wet... Is it suppose to be all wet or just part of it?
 
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Old 12-14-08, 07:10 PM
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Originally Posted by Jay11J View Post
Not a problem helping you out..

I wasn't aware you had the 400, and overall, how do you like it? I've had a few people come back here saying the pad is not all the way wet... Is it suppose to be all wet or just part of it?
Over all I like it, but . . .

The concept is pretty simple. It pours water on the top of the pad and it trickles down through it. The trickle down water also fills a reservoir at the bottom and two floats (primary and emergency backup) tell it when to stop filling. The pad also wicks up the water from the reservoir from the bottom. I have not spent much time touching the pad to see how wet is stays, but the 400 could not keep the humidity high enough for my house during the extended dry, cold conditions--it would max out at about 35% during those conditions, and I was trying for 40-45%. My house is 45 years old and not that tight (about 3200 sq ft total and 2400 sq ft of it heated). I worked with you on this forum working through that issue on a different thread--
http://forum.doityourself.com/humidi...ml#post1445803

I added a second humidifier connected to the same controller, and the humidity levels now remain constant at 45% without any problem so far (but the coldest, dryest part of the winter has not yet arrived). I expect doubling the capacity as I have will be more than enough.

I learned that the advertised sq ft ratings for these humidifiers are typically for tight homes, and the humidifier manufacturers have much lower sq ft. ratings for less tight homes, if you can find them. According to Aprilaire, The 400 is rated for 1000sf for a loose house, 2000sf for an average house, and 4000sf for a tight house (its really based on air changes per hour--see link below). After seeing these ratings, I can see why I had trouble in my old, not tight house. Here's the specs for all the residential Aprilaireunits: http://www.aprilairecontractor.com/p...iers/84492.pdf

I had to choose the model 400 (a drain-less model) as I have no drain in the basement (where the furnace is). Another difference with the 400 is that it has no flushing capability (because of no drain) and therefore they recommend replacing the pad halfway though the heating season (the other models use one pad per heating season). I believe if you have hard water (that will leave lots of mineral deposits), then this is likely a good recommendation.

So now I understand the real ratings, I believe the 400 works as advertised and adding a second one has solved my problem.

Thanks again for your help. This forum is great!
 

Last edited by jamitt; 12-14-08 at 07:25 PM.
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Old 12-14-08, 07:55 PM
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Originally Posted by jamitt View Post
I added a second humidifier connected to the same controller, and the humidity levels now remain constant at 45% without any problem so far
That's pretty high.. How cold is it outside?

Be no way we could do that here in Mn with that high of a setting.. We suppose to get down to -6˚ tonight, and -13˚ tmrw. night.. Right now, ours is keeping aroun 32% at 0˚.
 
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Old 12-15-08, 06:29 PM
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Originally Posted by Jay11J View Post
That's pretty high.. How cold is it outside?

Be no way we could do that here in Mn with that high of a setting.. We suppose to get down to -6˚ tonight, and -13˚ tmrw. night.. Right now, ours is keeping aroun 32% at 0˚.
I'm in Maryland. So far, we have had a few continuous days of nighttime temps in the low 20's and daytime in the 30's. With one humidifier, it would top out at about 35% with those conditions and a bit higher if I left the fan run continuously.

If you are getting 32% in those really cold conditions, you are doing great! (Glad I don't live in MN--too cold for me!!)
 
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Old 12-15-08, 08:54 PM
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Originally Posted by jamitt View Post
If you are getting 32% in those really cold conditions, you are doing great!
I can easly do 40% or more if I wanted to, but I have an outdoor sensor to protect the cold windows from heavy frost build up.


(Glad I don't live in MN--too cold for me!!)
The coldest I've seen here was -35˚ in 1996, that same day up north in Towers Mn they had -60˚
 
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