Furnace only runs when jumping T1/T2 on Control on burner


  #1  
Old 02-15-15, 12:23 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Furnace only runs when jumping T1/T2 on Control on burner

Hello Everyone,
I made it a whole 6 weeks trouble free since your help with the Honeywell WiFi thermostat install here. http://www.doityourself.com/forum/th...one-input.html

This morning I had no heat. I did some basic testing of the control, looking for voltage, checking burner, etc. What I found is if I jumper the T1 and T2 on the control it turns on and heats fine. So the issue is somewhere in the thermostat or relays/transformers I have setup. I’m kind of stuck on what to try next.
I tried my best at a wiring diagram below. I’m guessing the thermostat is OK. It’s new, it’s getting power because it is on (no battery backup) and it calls for heat so it ‘appears’ it’s doing what it should.

I’ve tried my best at a diagram below (apologies I know it’s a mess). I have a furnace, 3 zone EWC control panel (Pic 1) 3 transformers (Pics 2 and 3) one of which has a WGYRC inputs on it, 2 relays and something in pic 3 that I have no idea what it is other the label which says it’s a HP 15A-277 VACRES.

I do have 24 volts going to the T1/T2 on the control coming from that first relay. I'm not sure what combo of inputs to test on the main 24 vac transformer in pic 3. I can't find a combo that shows voltage but it must as that is what is wired to the relay that is sending power to the control. The 24 VAC transformer that goes to the EWC zone control panel also gets 24 volts on a test. Any suggestions would be fantastic. Thanks.



Zone Control Panel


120 VAC Shutoff


Transformer and Relays


Close Up of unknown device


Control
 

Last edited by cmn135; 02-15-15 at 02:47 PM.
  #2  
Old 02-15-15, 01:38 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
Are you getting 24 volts to your Control relay with a demand for heat?

Is it really R and W feeding it from the fan center?
 
  #3  
Old 02-15-15, 02:08 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Hi Houston. I have 24 volts going from the EWC zone control panel thermostat 1 input to the thermostat. I also have 24 volts on the main 24 vac transformer going to the EWC panel. And I have 24 volts going to the thermostat relay you helped me wire for the heat/cool changeover. The control relay that goes to the T1 and T2 on the control (I assume that's what you mean by control relay) actually only shows 18 volts regardless of whether the thermostat is calling for heat or not. (not sure if that's normal) My understanding is it should only send the 18-24 volts if it was calling for heat? But then again if it was stuck sending the 18 volt signal shouldn't the furnace stay in the on position and not off?

As far as your second question. The control relay where i noted R&W wires going to the fan center I should have clarified a little better. The colors are R and W but the W goes to white input and the R actually goes to the common. My mistake. I updated the diagram.

Last question. This pic below...fan center. If I put the multimeter to the R and C points I don't get any voltage. In fact I can't pair any of those inputs and find voltage. Is that normal? If so I don't get it. The control relay which is currently outputting 18 volts gets its power from the fan center setup does it not?
 

Last edited by cmn135; 02-15-15 at 03:12 PM.
  #4  
Old 02-15-15, 03:42 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
I called it a control relay because that is what your diagram called it.
I would normally call it an isolation relay.

It looks like bottom left is R and Bottom right is C. Do you agree with that?

I only see 1 wire on W. Is the orange wire nut in the bottom of the picture connecting an additional wire to W?
 

Last edited by Houston204; 02-15-15 at 04:41 PM.
  #5  
Old 02-15-15, 04:02 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Hi Houston. In the isolation relay the bottom left red wire goes to the C input on fan center. The bottom right white wire goes to the white input on fan center. And yes I agree on fan center the bottom left is R and bottom right is C. There is 1 white wire coming off of fan center. However...it goes to a wire nut and from there sends a white to the EWC zone control system input and the other to the isolation relay.

One question. When I hit the safety lockout button it doesn't do anything. Shouldn't it start the pump whether the thermostat was calling for heat or not and if not calling for heat it would shut off after a minute? Just trying to figure out if perhaps something is wrong with the primary control. It is re manufactured honeywell 8184 I put in a few weeks ago based on a different issue I was having. I still have the old one which does in fact work if it's worth trying to swap out.
 

Last edited by cmn135; 02-15-15 at 04:32 PM.
  #6  
Old 02-15-15, 04:48 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
Are you getting 18 volts across the load side of the isolation relay(which is connected to T and T) or across the coil side of it (which is fed by W and C)?

Does the fan run if you jumper G to R on the fan center?
 
  #7  
Old 02-15-15, 05:00 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
18-19 volts on load side to T and T. Nothing on coil side assuming you wanted me to test the W and C. And that's nothing when touching it on the isolation relay or directly on fan center. Nothing happens when I jump green and red on fan center.
 
  #8  
Old 02-15-15, 05:52 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
It sounds like the transformer on the fan center has failed.

Do we have the correct high voltage to the fan center?

I would manually turn the fan limit, if one is present, to run the fan and prove we have high voltage to the furnace.



If we are getting 120 volts to the transformer and nothing out of the secondary side, I would consider going back with a larger VA rating for the transformer (like 50VA). A new fan center would look better though.
 
  #9  
Old 02-15-15, 06:06 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Yes if I pull the white knob out the fan turns on. Is this failure also related to the thermostat not turning the burner on? Does it by chance feed power to the relay that turns on the furnace or something? Thanks! If that is the case I will definitely try for a new fan center over a new transformer.

Just to clarify...when i jumper T1 and T2 everything works. The burner goes, the fan turns on and heat stays on in all zones until I pull the jumper off.
 
  #10  
Old 02-15-15, 06:12 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
T and T would be from a different transformer.

I would pop the fan center off of the furnace and prove that we don't only need a new wire nut before shopping for a fan center.


This fan center has the larger 50 VA transformer but it is double pole single throw...
We would need a single pole double throw so it won't work.
http://www.amazon.com/Honeywell-R828...+VA+fan+center


This is the bigger 50VA fan center with a double pole double throw configuration that is probably required for your application...

http://www.amazon.com/Center-Switchi...an+center+dpdt

I would also add a 3 amp blade type fuse automotive fuse, using two spade connectors, between R and everything else, to protect the new transformer.
 

Last edited by Houston204; 02-15-15 at 10:40 PM.
  #11  
Old 02-15-15, 06:36 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Great thanks. Currently what is in there is a 40 VA SPDT. I get why moving to 50 VA. Curious why you recommend the DP instead of SP that i have now? Also, in terms of the 3 amp blade. Do you mean like an in line mini fuse? Between R and everything else..meaning just in the R wire to the fan center? That R goes to the system input on the EWC zone control. I don't suppose you have a picture from a previous install so i can be sure i know what you mean? Thanks again for your help. I assume you mean one like this that comes with regular wires and I will have to crimp fit spades on each end and add it in line between the R wire on the fan center and the R input on the EWC zone control? http://www.amazon.com/gp/product/B00...f_rd_i=desktop

I actually called a heating guy since we are sub zero the next few days and he groaned when I told him it was an electrical problem and I had already isolated it to somewhere before the primary control. He mentioned I should just jumper it and get through the night since he can't get any parts tonight anyways. Looks like that delay means I may get to fix it myself.
 
  #12  
Old 02-15-15, 06:45 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
I would see what is in use at this time.
If you need a spdt fan center it would be a much better price.

This is an old Radioshack pic.


I usually use 2 squeeze on spade connectors the way Trane does..


Name:  Fuse.JPG
Views: 981
Size:  16.9 KB

I wouldn't have a 50VA fan center on my van either.
I usually stock 40 va fan centers.
I would probably use a 3 amp fuse.

My eyes hurt. I can't see which fan center is spdt with a 50 VA transformer...
https://customer.honeywell.com/resou...0s/68-0088.pdf
 

Last edited by Houston204; 02-15-15 at 07:06 PM.
  #13  
Old 02-15-15, 07:00 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Thanks for the spade pic....that is VERY helpful. I've loaded a close up of the label. I will of course remove the fan center and check all wires first but it appears this current model is a 40VA SPDT relay model. Do you recommend going with a like setup or upgrading to the 50VA DPDT? Assuming I replace or got this one working...should I get a 24 volt reading when I touch the C and R on the fan center? (I assume yes)

 
  #14  
Old 02-15-15, 07:16 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
We have a lot of controls on a 40 VA fan center.
I would seriously consider going up to a spdt 50 VA fan center.

We should see 24 to 28 volts between R and C.

We should verify that 120 volts is feeding the fan center.
I have seen many melted wire nuts over the years.
 
  #15  
Old 02-15-15, 07:27 PM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Ok thanks I'll pull it and check all of that in the morning. One more question...something I don't understand. I was assuming the isolation relay was powered from the fan center. However...fan center is not working from the transformer. So I pulled the two wires going to R1 and R2. The contact points directly on the T1 and T2 show the 18 volts. So that's where I'm lost. My understanding was the relay would send voltage to the T1/T2 to tell it to turn the burner on but it looks like the primary control is the one supplying the voltage? What am I missing? Thank you!
 
  #16  
Old 02-15-15, 08:10 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
The isolation relay is just shorting the two T terminals together when it receives 24 volts to it's coil.

this is a spdt 50VA fan center...
R8285A1006/B


https://customer.honeywell.com/en-US...uct.Rank&asc=1
 
  #17  
Old 02-16-15, 03:12 AM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Ok thanks. So just to be sure I'm following the T1 and T2 points stay at 18 volts and when the thermostat calls for heat the fan center sends 24 volts to the isolation relay which shorts the two terminals together? Thanks again.
 
  #18  
Old 02-16-15, 06:13 AM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Well you were right. It was a melted mess. I'm gonna try to strip and rewire. Some parts are so bad I can't tell which wires are paired. I'll try to find a wiring diagram. Any idea how to prevent this in the future? Is there some kind of heat absorbing backing plate I can put between the junction box and the furnace cover?
 
  #19  
Old 02-16-15, 06:15 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
Yep. It's kinda like a light switch. Your hand flips a switch and closes the circuit between two wires. The 24 volts to the isolation relay is closing a set of normally open contacts.

If you measure voltage between the 2 load wires, you have "potential ". When you close the circuit it will read 0 volts.

Heat is created in the poor transfer of energy.
Loose wire connections get hot.
This heat causes oxidation which will compound the problem.

If the relay base that your relay plugs into is melted, you need a fan center.
 
  #20  
Old 02-16-15, 06:37 AM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Backing all looks fine on the plastic parts. Just cooked wires. I am rewiring now and will give it a shot. You certainly know your stuff! I may have to start paying you a retainer fee.
 
  #21  
Old 02-16-15, 07:05 AM
C
Member
Thread Starter
Join Date: Dec 2014
Posts: 42
Received 0 Votes on 0 Posts
Houston you brilliant son of a B it works! I'll probably replace it in the spring and run all new wires but for now I have a sick kid and two frozen pipes at a rental property. You've saved me at least a good $400 between this and the thermostat install...you the man! Here's what it looked like.

 
  #22  
Old 02-16-15, 09:50 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,425
Received 17 Votes on 14 Posts
That is great news
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: