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Trane XE1000 DFC


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04-17-14, 11:26 AM   #1 (permalink)  
Trane XE1000 DFC

Hi everyone, great place here. A little background on me and the issue I have. I am retired Navy A-Ganger. I've worked on refrigeration systems, mostly R-12 tho. I own a marine engine repair business and I work on and understand electrical and do a lot of DIY projects.

Ok, I had a AC guy come check my unit out. I told him that when the unit goes into defrost mode, cold air blows, cooling the house down, then of course the heatpump has to run again now to heat the house up. He said the air handler didn't have a jumper installed to turn on aux heat during defrost (which he said all heat pumps are suppose to be wired to do this). So he did whatever he did and left. When I notice the unit in defrost mode, seems it's blowing cold air again.

After he repaired (whatever he did) I had to change thermostats from a Honeywell RTH6350 to a Honeywell RTH7600. Honeywell said the first tstat might be bad. The first tsat would run the unit a long time even after the tstat showed the house was 70, which is where it was set to. It would basically run and run and turn off whenever it decided to.

What I would like help with is reading this wiring diagram to see how the unit turns on the aux heat when it goes into defrost being controlled by the Honeywell tstat?
Specifics would be great and I can understand the technical info given. I assume the coil bottom sensor (CBS) is what turns the unit on/off to defrost but I can't really see how it does it? Or if that is incorrect please explain.

My tstat wiring is as follows:
unit - 7600 tstat
R - RC -jumped to R
W - E-jumped to Aux
Y - Y
G - G
O - O/B
C - not used
T - not used

diagram split because it was too small to read
Attachment 30112
Attachment 30113

Also here is a pic of my original tstat.
Attachment 30111

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04-17-14, 12:46 PM   #2 (permalink)  
Hey boat, CBS detects 28* and closes, starting the timer in DFC. If it is still below 28* after 30 mins. it goes in defrost mode. Relay opens, stopping fan and energizing X2, which starts the heaters.

 
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04-17-14, 01:24 PM   #3 (permalink)  
Thanks for the info!!
So this should be right; W from the tstat is jumpered to X2 in the air handler/heater. This energizes the heater in defrost mode as you pointed out, and also, when the tstat is switched to emer heat.

So as long as X2 and W are connected all should be good. AND also, the black wire from the DFC should be connected to X2 from the X2 connection on the DFC.

And this is strange. I was with the guy when he removed the cover from the outdoor unit, and a black wire was there he said wasn't used. I believe that was the black wire from the DFC going to X2.

My original tstat had W jumped to X2, and there was a black wire connected to that X2. He removed the black wire from the tstat and said it wasn't used?
Now I'm wondering if he screwed it all up. I'll have to go look at the wiring outside and in the air handler.

Thanks again

 
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01-18-18, 02:20 PM   #4 (permalink)  
Trane XE1000 DFC

I have an old thread here about this but it won't allow replying to it anymore. So we'll try this again.
Issue: hp still wasn't turning on aux heat in defrost mode.
I went out earlier today and this is what i see.
Black wire (which is X2) from DFC is connected to white wire (which is W) going into heater control box thru control cable.
Black wire in the control cable wasn't connected so I contacted it to the above, so now I have X2/W both connected to black wire from DFC.

In the heater control box cable from Tstat and OD unit:
W's jumped together, Blacks jumped together,
and both of these are connected to the 3 white wires coming out of the plug from the heater control box.
This plug has (I believe it was) Red, Blue, Green and another white wire. These wires all go down to the FDR etc.

Questions:
1. I ran the unit in normal heat mode, and get 24v on the black to white to black wire in the OD unit when the unit is off. When it's running, the 24v goes away. Is that right?
2. Ran it in manual defrost mode, felt like heaters were on cos the air wasn't as cold as it's been the past few days when I noticed it in auto defrost.
3. Since I have DFC wires black to white and black in the cable all jumped together, I connected the black wire into the W connection on the Tstat. Was hoping the Tstat would show "Aux heat" in defrost mode, but that still doesn't work. I guess the Tstat has to internally power W for that to happen.

If you can't open the link let me know. It's a pdf drawing of my wiring diagram

 
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01-18-18, 02:29 PM   #5 (permalink)  
Apparently i can't share any image from Google drive. God i wish they would fix that crap already

 
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01-18-18, 03:49 PM   #6 (permalink)  
Welcome back. I'm sure you're mystified at how your thread has grown. An old thread cannot be brought back to life but I copied those posts and put them here for you. The board has undergone changes since you posted that. Picture posting is different. Follow this link... How-to-insert-pictures

Your old thread is over three years old. You're just getting to this repair now ?


~ Pete ~

 
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01-19-18, 08:43 AM   #7 (permalink)  
Posted By: PJmax Welcome back. I'm sure you're mystified at how your thread has grown. An old thread cannot be brought back to life but I copied those posts and put them here for you. The board has undergone changes since you posted that. Picture posting is different. Follow this link... How-to-insert-pictures

Your old thread is over three years old. You're just getting to this repair now ?
Well not exactly. Until the last 2 weeks when it's been bitterly cold here, is when i actually noticed how cold the air was blowing in defrost. I had changed wiring last winter and thought it was working as it should. Not so much until yesterday when I did what i posted yesterday.

My unit actually just went thru defrost a min ago. Tstat temp stayed at 70 during the cycle. A few days ago before I changed wiringwiring, in defrost the Tstat would drop to 68 ish.

So my concern now is the having the 24v on the black to white from DFC.
HOW is the W wire getting 24v in the air handler when the unit Is off?

 
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01-20-18, 02:19 AM   #8 (permalink)  


Nothing should turn off when your system goes into defrost mode except the outdoor fan motor.

The outdoor unit should send 24 volts to the air handler W terminal when it enters defrost mode.
This should energize the electric heat strips to temper the cold air that will blow into your house.

Trane systems usually use blue for the common circuit instead of the brown shown in my diagram.

 
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01-20-18, 05:35 PM   #9 (permalink)  
Posted By: Houston204

Nothing should turn off when your system goes into defrost mode except the outdoor fan motor.

The outdoor unit should send 24 volts to the air handler W terminal when it enters defrost mode.
This should energize the electric heat strips to temper the cold air that will blow into your house.

Trane systems usually use blue for the common circuit instead of the brown shown in my diagram.
Just crawled out from under house. Now I see how this works, and i learned something new. The W wire from Tstat always has 26v to it. It is connected to the 3 W wires in the AH in a plug. That plug has those 3 W wires with R,G,B. The R,G,B goes to the TNS.
The TNS also has a W wire coming out and the drawing refers to it as W/J. This wire goes to a another plug in the heater box along with the 3 W wires mentioned above from the other plug.
So in normal heat, W has 26v on it but not doing anything since no call for Emer. heat.
I turned unit on to aux heat(only), then crawled back under house. (Had the W wire disconnected from T stat first) crawled back in.
Touched W3 to W on (Tstat) no heaters kicked on).
Touched W2, no heater.
Touched W1, heaters kicked on.

So from what I observed, this is what happens:
When Tstat calls for heaters, the W which has 24v from Tstat applies that 24v to W/1 which goes to the heater relay. And that 24v is always connected to heater relay.
When the PCB closes contact 4 || 6, this allows W/J to complete the circuit and close the heater relay, turning on heaters.

So this is basically the same as it was connected. Dfc black(X2) to W (which is W1 in the heater plug).
So I'm still left with why the DFC will not activate W1 which already has 24v. And that doesn't make sense.
If DFC applies 24v to W1 in defrost, but W1 already has 24v, would mean there is nothing to tell the PCB to turn on the heater by closing 4 || 6?
Unless the W from Tstat looses it's 24v, then DFC sends it's 24v to PCB to close 4 || 6.
Still doesn't make sense!

If I could post a pic you could see my pic of heater controls that I noted with my Note 8.

 
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01-21-18, 11:41 AM   #10 (permalink)  
W to C should not always have 24 volts.

 
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01-22-18, 12:21 PM   #11 (permalink)  
Had to resort to using my desktop to upload some pics.
From what I see in the AH, the unit is wired correctly. Follow along with me.

1. W from Tstat and W from DFC X2 are connected together.
2. They are jumped to 3 WH wires coming out of plug 1-PF, 1-PM with R G B wires.
3. The 3 WH wires from opposite end of plug go to the second plug above 1-PF, 1-PM which feeds into the Heater relay etc.
4. The 4th WH wire which is WH/J comes from FDR and goes to top plug then goes to one side of Heater Relay (not shown on dwg but in pic).
5. In the top plug, WH1 and WH/J are connected to the Heater Relay.
6. WH1 is the activation wire from Tstat (which is normal), and WH/J (which is the 24v common side from FDR) completes the circuit when PCB closes contacts 4 || 6 to turn on Aux heating.

ALL of this is correct according to drawings and pics.


So 1 question I now have.
Is it possible that the White Rogers Tstat I have keeps W energized when system is in HEAT mode but off, THEN when system starts it turns off power to W so that when it calls for Aux Heaters it can energize W again?

READ THIS: The reaon I just asked this is, many other websites I've read recently state when system calls for HEAT, W IS ENERGIZED. They are NOT stating "calls for heat as in aux heat" they are saying heat as in heatpump heat mode.

ALSO, when my system starts this is what I hear. I'm sitting within ear range of Tstat. 1st click, system starts, fan comes on. Then I hear a 2nd click? Which from what I've observied MAYBE the Tstat turning off the power to W?

This seems to be how it is working. When I went under house last time, I left ALL the W wires disconnected. Went inside and Turned system to AUX mode (electric heat) and turned up Tstat so it would keep running.
Went back under house, when I touched WH from Tstat to the other WH wires, the heater relay turns on/off etc.

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01-22-18, 07:23 PM   #12 (permalink)  
Had an email conversation with White Rodgers today to test the Tstat.
And it works correctly. In normal heat mode, cont. between Rh & Y,G.
When called for aux heat, cont. between Rh & Y,G,W.
No volts on C - W when Tstat removed.

Now I have to go back to AH and disconnect W to Tstat and see if I get the 24v again.

 
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01-22-18, 09:08 PM   #13 (permalink)  
Do you have a model number for the air handler and a model number for the heat strip?

http://www.climas-trane.com.mx/docum...a%205%20TR.pdf


WHJ I understand, the other side of the contactor should probably land on 24 volt common.


Last edited by Houston204; 01-22-18 at 09:29 PM.
 
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01-23-18, 08:40 PM   #14 (permalink)  
No model # on the heat strip. There are 4 white round connectors with 120v black wire from heater relay to 2 of them. I believe the other 2 black wires are 2 common going to the heat senser. It is the black thing to the right of the big blue wire connector in the pic with a few wires going to it.

The AH is a TWE036C or something like that. Forgot to take a pic of the diagram in the door. But I've seen many different drawings and they are roughly the same. Like the THW36, TWV36 drawings are the same as mine etc. and my Tstat has R,B,BL,W,Y,G,O. All used except BL.

WH/J is the common side of heater relay coming from PCB, the other white wire which is actually W1 on mine goes to the Tstat. I have W1,2,3 but ONLY W1 activates the heater relay cos I tested it manually.

I haven't been back under the house to check the W1 again when it's disconnected from Tstat to see if it is still getting 24v.

When you say, "WHJ I understand, the other side of the contactor should probably land on 24 volt common."
You are talking about the 4||6 contactor? The other side of that is B.

 
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01-23-18, 10:06 PM   #15 (permalink)  
Yep, one side of the contactor is W and the other is C.
It kinda looks like someone did some incorrect wire connections.

 
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01-24-18, 06:55 PM   #16 (permalink)  
No it's wired just like the drawing

 
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01-24-18, 07:08 PM   #17 (permalink)  
Your drawing or the heat strip wiring diagram?

It looks like you drew what you have and it looks like what you have is incorrectly wired.

I am surprised that the missing heat strip panel isn’t laying around that air handler.
The heat strip diagram might be on it.

 
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01-25-18, 07:20 PM   #18 (permalink)  
I have the panel under the house, but it wasn't on when I bought the house. The wiring would have to be moved around some before it would fit back. It does NOT have a diagram on it.

None of the Trane heater strip drawings I've seen actually draw out the entire circuit. I have the factory wiring diagram for other heaters types from Trane and they are drawn the same as the AH drawing. Basically they only show the plug coming out of the heater box and they all say this is where the control wiring gets connected. Just like they say in Note 2 on the drawing above.

NOT sure why you are saying this is wired incorrectly?
WH/J goes to one side of heater relay, WH1 goes to other side of heater relay. This is EXACTLY how the diagram shows it is supposed to be wired. When 4||6 gets closed by PCB the heaters come on. Just like it is shown.

If it is the (2) 1-PM connectors confusing you, I had the same problem till I went and traced the wires.
One of the PM's has the WH/J wire (and that 1-PM is actually the plug at the heater box).
The other 1-PM connector is where the WH/1, the other 2 WH wires along with R,G,B which all go to the Tstat.


Last edited by Boatmagic; 01-25-18 at 07:58 PM.
 
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01-25-18, 09:43 PM   #19 (permalink)  
I see what they are doing.

Breaking the C to the heater contactor ,through a set of normally open contacts on a DPDT relay, unless the fan has a signal.

How are you determining when the heat strips are energized?
Are you measuring amperage?

READ THIS: The reaon I just asked this is, many other websites I've read recently state when system calls for HEAT, W IS ENERGIZED. They are NOT stating "calls for heat as in aux heat" they are saying heat as in heatpump heat mode.
This sounds like it is talking about non heat pump applications.
W is energized in your application with a heating demand greater than 2 degrees.


Last edited by Houston204; 01-26-18 at 06:16 AM.
 
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01-27-18, 07:40 AM   #20 (permalink)  
How I determined the heaters coming on was by doing the following:.
1. Disconnected the W wire from Tstst at the AH.
2. Turned system to Aux heat mode on Tstat so the compr would need to be run. Then turned the temp setting up to ensure heat turned on.
3. Went back to AH, touched W wire from Tstat to the WH/1 wires coming from the plug that has R,G,BL (which goes to second plug in heater box). The second plug is the one that has the R,B, 3 WH's and the WH/J coming directly from FDR..
4. When I touched W from Tstat to WH/1, the heater relay energized.
So I visually watched heater relay come on/go off.

So with that visually verified to be correct we also know that in Normal Heat mode, when Tstst calls for Aux heat it does in fact turn on heaters as well.
I verified this by running in Normal heat, measured temp at registers with my digital meter, then adjusted Tstst temp setting 2 higher and watched temp at registers go up another 10+ .

So now we know system works as designed, Aux heat runs/kicks heaters on when called for, runs in Aux mode with heaters only and also runs in Emer mode with heaters only.

I still have to check again to see if I'm getting the 24v again on the W from DFC to AH when running normally (which I shouldn't be getting but led me to this whole situation) LoL

If I see it again then no idea how it's getting there. Could only think the W wire is touching one of the other 24v wires that have power when system is off cycle.

If you recall back up in the conversation, I first saw the 24v on W at DFC when system was off cycle, then when system started up the 24v went awayand came back when system checked off again.

 
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01-27-18, 11:06 AM   #21 (permalink)  
Okay this all sounds clear to me except the last sentence.

If you recall back up in the conversation, I first saw the 24v on W at DFC when system was off cycle, then when system started up the 24v went awayand came back when system checked off again.
Is the thermostat satisfied at this time?
Did we measure W to C ?

 
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01-30-18, 03:27 PM   #22 (permalink)  
Sry, haven't been out to check this yet. Will update.

To answer your 1st question,
Whatever happened made no sense to me. Before system started up in heat mode that day, I had meter on the W coming from DFC (for the heater kick on in defrost mode). The W had 24v on it, and when it started up the 24v went away. Sat there till it cycled off and watched the 24v come back to W.

May..something was touching that day. But I will check it again soon.

 
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01-31-18, 06:59 AM   #23 (permalink)  
Measuring W to R will have 24 volts when no demand is present.
This is normal.

We want one meter lead on W and the other on C.

 
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02-03-18, 03:38 PM   #24 (permalink)  
Yes.
Back to the topic. Just came in from checking and found another issue I'll explain in a sec.

For this ongoing discussion here's what I know about my system.
1. When system is off, W retains 24v, which appears to be normal.
2. When system starts up in heat mode, that 24v goes away, again, normal.
3. If system calls for aux heat, this is when W/J, thru PCB contacts 4 6 closing, gives power to the heater relay to close contacts and power heater coils.
What I found today:
W1 connected to X2 from DFC had 24v when system off. Again that was normal as stated above.
Disconnected X2 from W1 at DFC, X2 had 24v when system in normal?
So this tells me the DFC internal relay, which closes to give 24v from Y-X2 to turn on heaters in defrost mode is closed. Which is broken!
My first thought when I found this was Maybe that's why my electric bill the past 2 months was $175/$245 cos the heaters have been running.
But, even when W1 was getting 24v from X2, the day I was at the AH wiring, the heaters are not on until I turned Tstat up to kick them on.


Last edited by Boatmagic; 02-03-18 at 05:43 PM.
 
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02-03-18, 08:07 PM   #25 (permalink)  
Are you measuring R to W, or B to W, or W to ground, or are you using a low voltage volt stick?



Last edited by Houston204; 02-03-18 at 09:00 PM.
 
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02-04-18, 09:43 AM   #26 (permalink)  
For the W and the X2 at DFC, W to ground, and then X2 to ground, that is with W, X2 disconnected.

I forgot this yesterday.
The W seems to work in conjunction with the Fan, I'll explain.
As stated earlier, at the OD, with meter connected to W-ground and system running in heat, W has 0 volts. When OD unit cycles off and AH fan still running, the W remains at 0 volts. Then about a min later when AH fan stops, this is when the 24v on W appears.

That is normal function of fan to run to finish getting all the heat out of coils.
And somewhere I read (can't remember where), the system is designed/interlocked so that the heaters can never come on UNLESS the AH fan is running. And that makes sense otherwise the heaters would burn up or overload etc.
So that explains why the W 24v doesn't come on until fan stops.

I just can't see where W is getting the 24v when everything is off? It's not from the Tstat cos I've tested that already.

If this was a military system, there would be a manual explaining every detail of operation. Cos I used to write/ edit these documents


Last edited by Boatmagic; 02-04-18 at 10:05 AM.
 
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02-04-18, 11:00 AM   #27 (permalink)  
It sounds like you are reading a back feed. Most likely through the thermostat.

I bet you had fun if you wrote them for mini split units.

 
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02-04-18, 12:48 PM   #28 (permalink)  
I'm sharing a link for you of a Powerpoint directly from Trane training. It explains operation of system using the original Baystat Tstat, which I had when I bought home and still have it.
If you look on pages starting at 30, this is the Tstat details. Then look at page 34 where it shows how it's supposed to be wired, which matches the drawings.
And If I'm reading what it says correctly, My system cannot turn on Aux heat in defrost UNLESS the black X2 wire from DFC is connected to black X2 to Tstat wiring, and then W1/W2 is jumpered in AH.

Also on page 38, where it explains 2nd stage Aux heating, the next page 39 states that X2 has 24v from DFC, yet we are not in defrost mode yet?

See if this makes sense to you?

https://drive.google.com/open?id=1ge...LLTQC3XVkc6uew

 
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02-04-18, 12:51 PM   #29 (permalink)  
It sounds like you are reading a back feed. Most likely through the thermostat.

Nope. I've tested Tstat with it disconnected according to the WR Tech rep via email. And it only powers W when you turn Tstat to Aux, Emer or adjust temp up in normal to kick on Aux heating

 
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02-05-18, 09:36 AM   #30 (permalink)  
Just a few minutes ago my system came on and went into defrost mode, and sure enough, the air was cold.
So this tells me the system the way it was wired works correctly.
Because today was the first time I've felt the cold air in defrost since I disconnected the X2 com W at DFC 2 days ago.

 
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02-05-18, 09:49 PM   #31 (permalink)  
I wonder if you would get the same results measuring W to B instead of W to ground.

You are reading backfeed from somewhere.

You can wire a relay to operate in reverse but that contactor is 24 volts to energize.

 
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02-07-18, 07:35 AM   #32 (permalink)  
It shouldn't matter really. Measuring W to gnd rules out the possibility of getting voltage from anything but W.
Also, sometimes B has 24v designed into a circuit.
Like on the sequencer, B has 24v always then when W gets 24v it completes the circuit.

Yesterday while looking at sequencer drawings/operation, I may be getting that 24v back from sequencer if the control end is always closed. Gotta check that now.

 
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02-07-18, 09:13 AM   #33 (permalink)  
I don't see a sequencer in the picture.

You have a transformer, contactor and a fan relay with a timer on it. That contactor is not going to energize the strips when 24 volts is removed


I recommend getting a clamp meter to measure amperage when demand isn't present.

Measure for 24 volts to it with and without demand.

Not to ground, across the coil.

 
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02-07-18, 05:54 PM   #34 (permalink)  
If you look at the pic I took of the AH and see the big blue wire nut. Just to the right of it against the back panel is the black sequencer. It's a double stack I believe.
If It's Not A Sequencer Them IDK what it is.

I gotta go back under and just start over till I find that 24v

 
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02-07-18, 08:12 PM   #35 (permalink)  
There is no sequencer in your wiring diagram.

I can't tell what that is next to the big blue wire nut. Probably a temperature limit switch.

Trane doesn't usually use sequencers.

When I look at Trane, Lennox and Bosch diagrams it makes me appreciate Carrier.

 
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02-08-18, 12:24 PM   #36 (permalink)  
Yes you may be correct. I have another pic of it looking right at it and it looks just like a sequencer, except there is no 24v connected to it.
It wouldn't make sense to have a sequencer and a separate heater relay.

Can you explain how the WH/J works. My Explanation.
On the heater relay, top Reds have 240v, bottom black wires are 240v out to heaters through the temp sensor.
On right side is W1, and the left side is WH/J.
So this relay gets 24v from WH/J every time the Fan turns on (which is on a delay), then only when W1 gets a 24v signal from Tstat do the heaters energize.
Would That Be Correct?

Now I know for a fact, that 24v I get on W ONLY comes back AFTER the Fan turns off.

 
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02-08-18, 05:40 PM   #37 (permalink)  
W makes the contactor but it will not get the C leg that is required to complete the circuit unless the fan relay is also energized.

If you measured at the heat strip contactor for 24 volts to ground it may still show up even with the fan off.

Other types (Warren) of heat strips may use a pressure switch to prove fan operation instead.

When you buy a thermostat it is usually configured for gas heat. This can damage electric heat strips if they are energized with no fan.

 
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02-09-18, 08:56 AM   #38 (permalink)  
"W makes the contactor but it will not get the C leg that is required to complete the circuit unless the fan relay is also energized."
Ok, So WH/J is the C leg. Yes I see this on the drawing.

"If you measured at the heat strip contactor for 24 volts to ground it may still show up even with the fan off."
Ok, then that would explain the 24v on W when system turns off.
So how is that possible?
If I'm correct, none of the other 7 wires in the cable have 24v in off except R from TNS, so W couldn't get 24v from any of those other wires even if they were touching. Because when system starts the 24v goes away


Last edited by Boatmagic; 02-09-18 at 09:13 AM.
 
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02-09-18, 05:29 PM   #39 (permalink)  
Do you feel like the expensive electric heat strips are heating when they should not be, or are you just curious as to where you are picking up a back feed reading when you measure W to ground outside ?

Are you dead set against measuring for 24 volts at the heat strip contactor?

This measurement should be taken across the 2 low voltage terminals on the contactor in your air handler.

If you are unable to take this measurement and just want possible causes for the false reading you need to start isolating heat pump, thermostat and air handler.

​​​​​This is the longest way to a solution.

I just get my clamp meter an test at the air handler.

Theorizing possible causes for a false reading without actually measuring at the air handler is not my specialty.

I recommend getting a clamp meter.

Just get the right tool and measure at the right location.

A UT210E would be a good choice. $40 and I highly recommend it.

I walk around with one on my belt 5 days a week.
A true RMS meter that can take abuse well.


Last edited by Houston204; 02-09-18 at 05:44 PM.
 
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02-13-18, 02:50 PM   #40 (permalink)  
No, I'm positive the heaters aren't running all the time as I've watched the contactor cycle on/off when I had Tstat set to Aux then went to AH and connected the W wires and watched relay go on/off.
I'm going back under soon when it dries out some..Been raining here for days.

I'm mostly concerned WHY the W has 24v when system is off as that doesn't make sense and I cannot find any documentation that specifically explains how the FDR works.
As it is right now (until I find otherwise), one would believe it's designed to have 24v on W when off, and when it starts that 24v goes away. But that still does not make any sense at all and there would be no reason for it to work that way,

I do still need to go back and measure across the 2 terminals on heater relay as you just mentioned. I believe when I first did it I was measuring each side to gnd.
Also, yes I have clamp-on amp meter and all kinds of toys. I am a Marine Technician and do this stuff all the time, lol, just not on heat pumps..

Will update all my reading when I get to it and post for you.

 
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