4 Burned Transformers and counting

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  #41  
Old 05-16-09, 02:41 PM
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Originally Posted by daddyjohn View Post
OK no problem the terminal under the blue wire kinda looks like an O not a C

btw- get an extra 40 va transformer [a cheapie, make sure it has multiple voltage primary wires] and get your meter back. We're going to make a little test.
Should he maybe fuse every one of the transformer wires, also?
 
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  #42  
Old 05-16-09, 05:05 PM
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hey ec

yeah man it's always those 5 minute jobs that make you nuts. He has fuses on both the primary and secondary of the transformer. We're going to test run the outdoor unit with a throwaway transformer. Did you see the two things I pointed out in the pics? The cooling mercury bulb on the old stat and the chafed wire on the outdoor section? It looks like the problem is in the cooling circuitry. I'm thinking that either R is going to ground without a current consuming device in the circuit or something in the outdoor section is gomered.
 
  #43  
Old 05-17-09, 11:47 AM
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Originally Posted by daddyjohn View Post
hey ec

yeah man it's always those 5 minute jobs that make you nuts. He has fuses on both the primary and secondary of the transformer. We're going to test run the outdoor unit with a throwaway transformer. Did you see the two things I pointed out in the pics? The cooling mercury bulb on the old stat and the chafed wire on the outdoor section? It looks like the problem is in the cooling circuitry. I'm thinking that either R is going to ground without a current consuming device in the circuit or something in the outdoor section is gomered.
I guess I am not seeing what you see in the old stat mercury bulb. But I'm thinking that even if there is, since the short occurs when in cooling - one has to still distinguish as to whether the short at any device is causing the damage to that device (the thermostat and maybe the mercury bulb) or be a result of the cause of the short, since it shares the same circuitry. Sort of like how a lightning strike can take out a number of components at once -not just one.

Wouldn't you think if R had anything to do with it, directly, that the short would occur in heating also? He seemed to infer that the problem occured when wife switched from the heat to the cooling mode -as if the cooling mode is soley the culprit. Although he did hint it may be in any switching -but that has to be easy to test for, as all he has to do is get it back in heat mode and test run the system. And if it blows then(again), then maybe make a second attempt, leaving it in same (heatmode)position, so he can see if the actual switching is doing it, or not.

Something outside "gomered"? Gomered? Like Gomer Pyle?
Would still have to try to find what it is though.
We know that it has to be something. It's a matter of finding what, though.

This is one of these problems where you feel like maybe you could solve it if you were there and could look at every single wire route and connection. That is why I'd like to see a schematic of the cooling and heating, to see where there is and is not commonality between the heating circuit and the cooling circuit.
 
  #44  
Old 05-18-09, 10:23 AM
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IMHO, replace coil on reversing valve, take brown wire back off stat, (not needed its for a thermister) and take apart and resplice all low voltage connections at outdoor unit
 
  #45  
Old 05-18-09, 04:10 PM
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Originally Posted by daddyjohn View Post
OK no problem the terminal under the blue wire kinda looks like an O not a C

btw- get an extra 40 va transformer [a cheapie, make sure it has multiple voltage primary wires] and get your meter back. We're going to make a little test.
My apologies for the delay in posting...weekends are usually crazy with activities. I have my meter back(which is how I tested the resistance on the supplemental heat unit's contactor relay - posted on 5/15 @ 6:42pm), but unfortunately I didn't get a chance to buy another transformer yet.
 
  #46  
Old 05-18-09, 04:20 PM
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Originally Posted by daddyjohn View Post
hey ec

yeah man it's always those 5 minute jobs that make you nuts. He has fuses on both the primary and secondary of the transformer. We're going to test run the outdoor unit with a throwaway transformer. Did you see the two things I pointed out in the pics? The cooling mercury bulb on the old stat and the chafed wire on the outdoor section? It looks like the problem is in the cooling circuitry. I'm thinking that either R is going to ground without a current consuming device in the circuit or something in the outdoor section is gomered.
Does this look like a culprit to anyone?
http://farm4.static.flickr.com/3338/...bae6edeb_b.jpg

It is the sheath for the low voltage wiring and it was rubbing up against a copper pipe that is connected to the reversing valve. I also noticed something else...

http://farm4.static.flickr.com/3328/...8a812663_b.jpg
The exterior cover was rubbing up against the reversing valve...which resulted in...

http://farm3.static.flickr.com/2301/...b9abc400_b.jpg

Now this could be common rust...but I think I see evidence of a short. Does anyone agree?
 

Last edited by EliottIzzy; 05-18-09 at 04:22 PM. Reason: Fix Hyperlink
  #47  
Old 05-18-09, 04:44 PM
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Originally Posted by EliottIzzy View Post
Does this look like a culprit to anyone?
http://farm4.static.flickr.com/3338/...bae6edeb_b.jpg

It is the sheath for the low voltage wiring and it was rubbing up against a copper pipe that is connected to the reversing valve.
Could be. But it wouldn't be if the unit still blows a transformer fuse even after you moved the wire away from the pipe.

I also noticed something else...

http://farm4.static.flickr.com/3328/...8a812663_b.jpg
The exterior cover was rubbing up against the reversing valve...which resulted in...
Those 2 brown streaks on the solenoid coil that looks like it may have 2 horizonal burn and flash marks? Were wires laying at those 2 spots, and you moved wires out of the way? Is that flat piece that has the 2 streaks on it made of metal or plastic? If plastic, the streaks could have eminated from in the coil itself. If metal, then not.

http://farm3.static.flickr.com/2301/...b9abc400_b.jpg

Now this could be common rust...but I think I see evidence of a short. Does anyone agree?
What is that thing?
 
  #48  
Old 05-18-09, 04:45 PM
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Test the coil for resistance [not just continuity] but I believe you found the problem at that burn mark on the sheath of the low voltage cable. Carefully slice the cable sheath open with the tip of a razor knife and see if you can tell which color wire is damaged.
 
  #49  
Old 05-18-09, 04:48 PM
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BTW...The AC unit is now humming along...and has been since approximately 11:30 pm on 5/15.

Regretfully, it was necessary for me to disconnect all the low voltage wiring and verify that the wires were not grounded or crossing over amongst each other.

Here is a picture of the disconnected wiring at a junction box and conduit that feeds the low voltage wiring to the outside unit. The line voltage is coming in from the right and hooks up above the low voltage wires.
http://farm3.static.flickr.com/2198/...1c9ac434_b.jpg

Here is a picture of the disconnected low voltage wiring inside the unit. Notice the pipe that runs up and left towards the conduit...thats where the "unauthorized" contact took place.
http://farm3.static.flickr.com/2125/...d0aa45a3_b.jpg

And some pictures after the re-splicing/repair...
http://farm3.static.flickr.com/2003/...28f62d61_b.jpg
http://farm3.static.flickr.com/2157/...e4ae6e94_b.jpg

And a picture of the secured ground wire at the supplemental heat unit...
http://farm3.static.flickr.com/2184/...2430067b_b.jpg

And a picture of the re-spliced low voltage wiring at the AH...prior to reinstalling the new transformer.
http://farm3.static.flickr.com/2092/...97e87767_b.jpg

And finally a picture of the AH prior to firing it up for the first time in 2 days...
http://farm3.static.flickr.com/2374/...ff7f8b4e_b.jpg
 
  #50  
Old 05-18-09, 04:59 PM
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Tranformer hasn't blown yet (fingers crossed)..however, no one had fiddled with the stat...and it did run for well over a month the last time i swapped it out. Granted...I did not inspect the wiring last time.

Those are definately burn and flash marks...the piece is made of metal and it was touching up against the exterior metal grate/cover seen on the second picture.
 
  #51  
Old 05-18-09, 05:04 PM
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Eliott, re-read post from 12:23 and yes repair burnt wire from "culprit pic".

You have the stat wired right, except for X2 from what I can see, and yes its a H/P stat. If you want to take the "y" out of the equation as a possible short in the conductor itself put the brown wire in its place at the the stat and outdoor unit. Electricity doesn't care what color the wire it runs through is.

Like I said, low voltage shorts can be tricky but I am pretty confident its the solonoid
 
  #52  
Old 05-18-09, 05:07 PM
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Man, you guys type fast
 
  #53  
Old 05-18-09, 05:43 PM
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Originally Posted by dun11 View Post
IMHO, replace coil on reversing valve, take brown wire back off stat, (not needed its for a thermister) and take apart and resplice all low voltage connections at outdoor unit
Shouldn't I test the coil at the reversing valve before replacing it? After all, wouldn't a faulty coil prevent refrigerant from doing it's job...if I'm not mistaken, the solenoid energizes in cool....am I right?

The BROWN wire is disconnected at the stat and AH...only wired at outdoor unit and junction box...since I hadn't realized that it wasn't necessary when I reassembled everything.

Also, the low voltage wiring has been inspected, disassembled, tested for continuity between each other, tested for grounding to the cabinet, respliced, and reconnected at both the AH and outdoor unit. Everything looks good.
 

Last edited by EliottIzzy; 05-18-09 at 05:48 PM. Reason: Correct spelling
  #54  
Old 05-18-09, 05:47 PM
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Originally Posted by daddyjohn View Post
Test the coil for resistance [not just continuity] but I believe you found the problem at that burn mark on the sheath of the low voltage cable. Carefully slice the cable sheath open with the tip of a razor knife and see if you can tell which color wire is damaged.
I got a reading of 11.2 ohms...does that sound right?
 
  #55  
Old 05-18-09, 05:54 PM
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Originally Posted by dun11 View Post
Eliott, re-read post from 12:23 and yes repair burnt wire from "culprit pic".

You have the stat wired right, except for X2 from what I can see, and yes its a H/P stat. If you want to take the "y" out of the equation as a possible short in the conductor itself put the brown wire in its place at the the stat and outdoor unit. Electricity doesn't care what color the wire it runs through is.

Like I said, low voltage shorts can be tricky but I am pretty confident its the solonoid
Where should X2 be connected to on the stat? At the AH it was (previously) connected to the white wires...(W) as seen in this picture...but I've left it disconnected, since the stat instructions don't call for it.
http://farm3.static.flickr.com/2352/...1a93c90a_b.jpg

Am I mistaken? I'm looking at pages 20,24,25,26 of the manual...
http://www.ritetemp-thermostats.com/...tion_guide.pdf
 
  #56  
Old 05-18-09, 06:13 PM
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Yes, the solonoid energizes in cooling for Trane and most manufacturers, but not all, like Rheem for instance. This is to insure if it fails it fails in the heating mode.

A faulty coil has nothing to do with refrigerant doing its job, it simply energizes or de-energizes, which in turn magneticaly lifts or drops, opens or closes, whatever you want to call it, a sping loaded valve that flows refrigerant in one direction or the other.

If you repaired all the low voltage connections thats good I'am sure they needed it from the pictures I saw.

What I was trying to get to by suggesting replacing yellow for brown was that I knew your problem was either the solonoid or an intermittent short with either "y" or "o" so, if you replace the suspect conductors with unused or unneeded conductors you eliminate the possible short.

As far as the reading on the coil, its within range, but hey at this point what would it hurt?
 
  #57  
Old 05-18-09, 08:26 PM
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The RV coil is ok, not shorted. The burn mark on the one cable at the outdoor unit, what color wire inside the cable took the hit? So you are saying that the cable was touching the small tubing that comes out of the top of the RV by itself? That is the hot gas line, make sure your repairs don't touch that tubing. Tuck the wiring up along the bottom of the control box and secure it there. However, I'm still not totally happy. Remember I had asked to see the wiring diagram for the outdoor unit? When a heat pump goes into defrost during the heating cycle, the defrost control board does several things one of which is to turn on the heat strips in the AH so you don't start blowing cool air into the house. I want to see which wire in the outdoor unit they used for that function. I'm thinking it's the black and with the wires you disconnected in the AH you've lost that function. Notice in the one photo that shows the low voltage at the AH before they were taken apart? It looks like the 2 black wires and the white wire from the stat go together with a white wire that goes up to the heat strip section. In the after picture you have the white from the stat going to the white that goes to the heat strips and the 2 blacks taped off. I think the black from the outdoor unit needs to join up with the white from the stat and the white from the heat strips while leaving the black from the stat taped off. I imagine the wife and kids are happy to know it wasn't them causing the problems.
 
  #58  
Old 05-18-09, 09:12 PM
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Originally Posted by daddyjohn View Post
The RV coil is ok, not shorted. The burn mark on the one cable at the outdoor unit, what color wire inside the cable took the hit? So you are saying that the cable was touching the small tubing that comes out of the top of the RV by itself? That is the hot gas line, make sure your repairs don't touch that tubing. Tuck the wiring up along the bottom of the control box and secure it there. However, I'm still not totally happy. Remember I had asked to see the wiring diagram for the outdoor unit? When a heat pump goes into defrost during the heating cycle, the defrost control board does several things one of which is to turn on the heat strips in the AH so you don't start blowing cool air into the house. I want to see which wire in the outdoor unit they used for that function. I'm thinking it's the black and with the wires you disconnected in the AH you've lost that function. Notice in the one photo that shows the low voltage at the AH before they were taken apart? It looks like the 2 black wires and the white wire from the stat go together with a white wire that goes up to the heat strip section. In the after picture you have the white from the stat going to the white that goes to the heat strips and the 2 blacks taped off. I think the black from the outdoor unit needs to join up with the white from the stat and the white from the heat strips while leaving the black from the stat taped off. I imagine the wife and kids are happy to know it wasn't them causing the problems.
I'll have to double check tomorrow...but I think it was the red. Yes, the cable was right up against that pipe...it's insteresting that issues hadn't come up before. I don't think that sheath was designed to withstand that kind of heat for years....but I could be wrong. Then again, I had previously changed out the contactor, perhaps I inadvertently fixed one problem while causing another.

Here are two diagrams...there is one more but the print is unreadable. I will try scanning.

Cooling Diagram...
http://farm3.static.flickr.com/2386/...731887c6_b.jpg

Heat Pump Diagram...(I think this one applies to my unit.)
http://farm4.static.flickr.com/3391/...fb9f5909_b.jpg

So as a precaution, do you think I should hook up the black wires to the white ones at the AH?
 

Last edited by EliottIzzy; 05-18-09 at 09:57 PM. Reason: Fix Hyperlink
  #59  
Old 05-18-09, 10:39 PM
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I want to double check the X2 terminal in the outdoor unit. If you look at the single speed heat pump connection diagram, do you see X2 in the outdoor section? It has B or BR/X2 going to it. I think that wire is what brings on the strip heaters during defrost.
 
  #60  
Old 05-19-09, 04:20 AM
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The black wire X2 is for the elec heat, the reason they want it disconnected at the stat is because that stat does not have an aux heat function, its internal.

Sorry, had to re-read post to catch that.

You need to hook it back up at the air handler for elec heat to work
 
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