Relay Transformer Dead - killed by circulator pump???

Reply

  #1  
Old 12-09-08, 06:47 PM
Member
Thread Starter
Join Date: Dec 2007
Location: pierce county, washington state
Posts: 30
Received 0 Votes on 0 Posts
Relay Transformer Dead - killed by circulator pump???

The Situation

My parents are out of the house for a few days, so the thermostats had been turned down, but when I came to check on the place, the house was too cold. I went down to check the boiler and found the power on, but the boiler was cold. I manually opened a zone valve - which should have caused the boiler to fire - nothing, no reaction at all.

I noticed a strange odor, that seemed to be coming from the relay transformer, I removed the cover and could see burn marks on the transformer. With my volt-meter, I found power going to the transformer - 120vac - but nothing leaving it. Then I saw, on the floor, under the B&G circulating pump, a bit of spring and a piece of metal that I recognized as part of the coupler assembly. Looking closer at the pump, I could see metal dust covering the motor and bearing bracket.



My guess is that the pump's coupler assembly had broken and with no one around to hear its screams, it had continued to spin and grind the coupler assembly pieces, until it jammed or burnt-out the motor. This may have somehow overloaded the relay transformer. I checked the contacts for the circ. pump and they are burnt.

I already have a new Taco 007 to replace the B&G pump.

--- Questions are below, after the photos. ---

General System Info

Gas, Hot-water (original install about 1971)

- 3 zones/zone valves - each with its own thermostat

- 2 circulating pumps

- one pump for front/back zones, upstairs - baseboards
- controlled by relay transformer

- one pump for basement zone, in cement slab floor - with aquastat
- controlled by on/off power switch

More information on this system and its previous problems can be found in DIY Post:
http://forum.doityourself.com/boiler...ml#post1341224

Here's a diagram Trooper created of this system from the earlier post:



Photos

Relay Transformer from April 2008:



Relay Transformer now - December 2008:
- burnt contacts and burn marks on transformer



Current wiring diagram for Zone Valves to Relay Transformer:



Other transformer (?) - possible damage?



Questions

What I need to know is ...

Does this sound right - that the circ. pump somehow killed the relay transformer?

Is it possible/likely that other components were damaged? If so, what should I check?

Can you recommend a replacement relay transformer? Is one better than another for this system?

Bonus Problem/Solution

In the earlier post on this system - http://forum.doityourself.com/boiler...ml#post1341224
- Trooper had suggested that I could setup the basement circ. pump to run only when there's a heat call like this:


But I'm thinking, that if the pump doesn't run continuously, then the water is not circulating past the aquastat and since the aquastat is close to the boiler, it may stay a little warmer then other parts of the basement, so parts of the basement may get too cold before the call for heat gets by the aquastat. Does this sound right?

Do some relay transformers have a timer or some other way to periodically run the pump so that the water circulates past the aquastat, maintaining a more even heat distribution than just having the water sitting?

Can/should I get a relay transformer that will handle both pumps? - or - Just leave things as they are - upstairs zones/pump controlled by relay - basement pump runs by manual switch?

Thanks, for any and all help ...
 
Sponsored Links
  #2  
Old 12-09-08, 07:33 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Here's my theory ...

Heat call came in, coupler gave up it's ghost. The heat call couldn't satisfy because the coupler broke, and the circ just spun and spun ... heat call continued for a LONG time ... and the transformer burned up just from being energized that long ... maybe it's not really rated for continuous duty ... OR... as the house cooled, ALL THREE zones called for heat... maximum load on the transformer and it just couldn't cut it ...

The relay contacts could have been damaged if there was a locked rotor on the circulator, but it looks more like arcing at the contacts... why after all these years would it get damaged ... I dunno ...

I doubt if the transformer in the boiler is damaged.

The circ motor _might_ be OK ... depending on how long it sat there with power on and locked up.

The aquastat on the slab heat is a high limit ... stops the call for heat to the floor if it goes over setpoint. I don't think you would see much difference with or without constant circulation. Wait ... 'ang on a sec' ... the way I recommended wiring it, the circ would continue to run as long as the basement thermostat was calling for heat. Only the zone valve would close and the boiler stop firing when the aquastat was satisfied. The circ would continue in the floor till the thermostat was satisfied ... I think it's OK ...
 
  #3  
Old 12-09-08, 08:58 PM
Member
Thread Starter
Join Date: Dec 2007
Location: pierce county, washington state
Posts: 30
Received 0 Votes on 0 Posts
Thanks, Trooper

Thanks for the info. Can you recommend a new transformer that can operate both pumps?

I don't really know what I'm looking for, but of the ones I found, they talk about controlling one pump for each zone. If I'm guessing right, I think I can get one for "two-zones." That will handle both pumps and all three zones.

I found brand names like: Azel, Argo, Taco and Honeywell ...
- Azel - SP-81 - one zone / SP-82 - two zones
- Argo - AR822II - one zone / AR861-2II - two zones
- Taco - SR501-2 - one zone / SR502-2 - two zones
- Honeywell - R8845U1003 - one zone / R845A1030 - two zones

Is one better than another for this system?
 
  #4  
Old 12-09-08, 10:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
I think to get the heat going again all you need to do is install the new coupler, and temporarily wire a new 40 VA transformer in place of the burnt one. The relay itself will probably still switch the circ ... cut the wires and wire nut the new transformer in the old one's place.

The way your system is wired, you can't really use one of the multi-zone panels. and you can't just replace the relay, becuz you need to power the zone valves from the transformer...

I would wire an external transformer to power the valve motors, and replace the burnt box with an 845 (or the less expensive 8845) ...

I need to think about this more ...

Do you remember where we found the PDF file for your zone valves ? or do you still have it ? if so, I'll PM ya...
 
  #5  
Old 12-10-08, 12:47 AM
Member
Thread Starter
Join Date: Dec 2007
Location: pierce county, washington state
Posts: 30
Received 0 Votes on 0 Posts
I think to get the heat going again all you need to do is ... temporarily wire a new 40 VA transformer in place of the burnt one.
Do you think I can find a transformer at Radio Shack or some computer build shop?

Do you remember where we found the PDF file for your zone valves ? or do you still have it ?
As far as I know there was no PDF file - I did find an old instruction sheet. The best I can do is below:

Instruction sheet page 1:


Instruction sheet page 2:


Instruction sheet page 3:


Instruction sheet page 4:


I would wire an external transformer to power the valve motors, and replace the burnt box with an 845 (or the less expensive 8845) ...
Dose this mean that the Honeywell - R8845U1003 - one zone box - is not a replacement for the burnt box?
 
  #6  
Old 12-10-08, 04:02 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
No, forget about RS ... Home Depot, Lowes, Supply house. You want a "40 VA CONTROL TRANSFORMER" ... If you get one like the one that's inside the boiler, you can mount a 4" box on the boiler next to the relay and tie it in ... in fact, if you put crimp lugs on the two 24V leads, you can just connect them right to the terminal strip screws and cut the burnt transformer leads off.

Correct, the transformer in the 8845 ... (or some/all the others you listed) ... is not big enough to power the zone valves... it will suffer the same fate as the one in your relay box, but sooner. I believe there ARE models that will directly replace that one ... almost positive that I saw one on W-R site ... I think most systems built today use external transformers when needed...

One plus to using an external tranny, if it ever goes bad again, only the transformer gets replaced.

I'm still thinking about this ... your zone valves would work with Taco ZVC panels. If you got one of them, it would also run your main circulator. Then, use the 8845 to run the basement floor circ ... lemmee draw that up ...

Thanks for posting that brochure... I did find something on the W-R website, but not as complete as that.
 
  #7  
Old 12-10-08, 04:52 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Get the heat back on ...

First, test the motor on the existing circ to see if it still runs.

If so, replace the coupler. If not, replace circ.

Pick up a 24 V transformer and connect it in place of burnt one.

I believe existing relay will still operate circ OK for now.

Heat is back on...

Purchase Taco ZVC 403/404 zone valve control panel, and Honey R8845 relay.

Replace existing relay box with ZVC panel.

Add 8845 relay to basement zone.

Wire per schematic...
(corrected schematic) [edit 12-25-09 : It appears there is still an error in this drawing. The main circ should be wired to the N/O Normally OPEN connection]

 

Last edited by NJT; 12-25-09 at 05:33 PM. Reason: drawing corrections
  #8  
Old 12-12-08, 06:25 PM
Member
Thread Starter
Join Date: Dec 2007
Location: pierce county, washington state
Posts: 30
Received 0 Votes on 0 Posts
It's not pretty - but heat is on

Thanks for the advice Trooper.

It took some call'n, but I was able to find a transformer Thursday. It turned out, the only place I could find that had one on the self, was near my parent's place. I went to the house, test the motor - all good. Picked-up the transformer and got it installed.

The new transformer was a little bigger and didn't fit where the old one had been and I didn't want to drill holes to mount it, since the current setup is just until I can get the new Taco control panel ... so, I found some existing screws that fit the mounting bracket, then I just cut, spliced, jumped, capped ... until it was wired-up.

New transformer & old relay box:


New transformer - side/label view:


Turned the power back on and everything worked!

Thanks again!
 
  #9  
Old 12-13-08, 08:02 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
I woulda mounted a 4" utility box to mount the transformer on, but as long as it's safe (i.e. no exposed 120VAC) and it works, it's OK for temporary.

Good to go for now ... are you gonna wait till spring to make the other changes?
 
  #10  
Old 12-14-08, 06:10 PM
Member
Thread Starter
Join Date: Dec 2007
Location: pierce county, washington state
Posts: 30
Received 0 Votes on 0 Posts
I took the above pics to show the connections/splices/caps/tapes - I guess I should have posted a pic with the cover on too. All I did was bend the top a bit to allow space for the wires to pass through and then popped the old cover on. The only exposed wires are the insulated ones you can see. No exposed 120VAC connections.

New transformer & old relay box - cover on:


are you gonna wait till spring to make the other changes?
Not unless I have to. I've been kicking myself for not getting them done already. Right now we are at the start of a rare cold spell here, if the weather reports are right, so it will have to wait until it warms up, temp gets back to normal. Getting the new parts in has definitely moved up the priority list!

Just in case you you were wondering, Trooper ... yes, I'm sure I'll have more questions!!!

Appreciate all the help
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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