Bad Zone Switching Relay (s)?

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Old 06-17-09, 05:32 AM
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Bad Zone Switching Relay (s)?

This a three zone oil-fired hydronic heating system that I put in a dozen years ago and that hasnít given me any problems other than having to replace the R8182H Aquastat in October of last year.

Last week when I tried out the system after topping off the water following a water line leak elsewhere in the house, the boiler fired up for domestic hot water and in response to the thermostat for Zone 1 which is, of course, controlled directly by the Aquastat. The YHR845A switching relays for Zones 2 & 3 at first clicked and hummed, but the circulators didnít start up and the burner didnít fire.

So I replaced the relay for Zone 2 which had been getting a bit noisy of late, but no joy: the relay clicked and hummed, but no further action. The Zone 3 relay now gave no response at all, except if I first activated the Zone 2 relay and then turned up the thermostat for Zone 3. Then the Zone 3 relay would still not click, but it would start to hum very loudly. Just to see what would happen, I replaced the Zone 3 relay with the old one from Zone 2 - same result: no click, but a loud hum when the Zone 2 relay is activated.

I made quite sure that I wired the replacement relay for Zone 2 in exactly like the old one, and Iíve checked and re-checked the wiring there and back to the Aquastat - all is as it should be.

At this point, Iím about ready to get a new relay for Zone 3 as well, but before I do that, I would very much appreciate suggestions as to what might be going on and some guidance as to how to go about trouble shooting to make sure it is indeed the switching relay that is causing the trouble, and not the Aquastat.

Thanks.
 
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Old 06-17-09, 05:42 AM
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There are too many variables here. Are the zones tied into ZR + ZC terminals on the aquastat. If so the pumps will not start until the boiler gets hot enough but the should still fire the boiler. IF not tied into ZR + Zc the pumps should come on but not fire the boiler. Can you show the wiring? A diagram would be best if it is doable. If not pictures may help. If it worked OK before it should have worked the same when turned off and back on.
 
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Old 06-17-09, 06:11 AM
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Originally Posted by rbeck View Post
There are too many variables here. Are the zones tied into ZR + ZC terminals on the aquastat. If so the pumps will not start until the boiler gets hot enough but the should still fire the boiler. IF not tied into ZR + Zc the pumps should come on but not fire the boiler. Can you show the wiring? A diagram would be best if it is doable. If not pictures may help. If it worked OK before it should have worked the same when turned off and back on.
Yes, the zones are tied to the ZR & ZC terminals on the Aquastat.

I'm not too familiar with the workings of this Board yet, but I'll see if I can figure a way of posting the wiring schematics from the on-line manuals, if that would be of any help.

 

Last edited by Vander; 06-17-09 at 08:44 AM.
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Old 06-17-09, 08:50 AM
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Let's see if this will work.

OK, obviously it didn't. Back to the drawing board.
 
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Old 06-17-09, 11:53 AM
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I give up. I'm unable to upload the schematic. I've tried several URLs, the last one from Picasa: <a href="http://picasaweb.google.com/Rocosil3/Miscellaneous#5348370387014813538">http://picasaweb.google.com/Rocosil3/Miscellaneous#5348370387014813538</a> .

Sorry, but that's the best I can do right now.
 

Last edited by Vander; 06-17-09 at 12:10 PM.
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Old 06-17-09, 12:50 PM
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We understand how it is supposed to be wired we are wondering how yours is wired.
 
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Old 06-17-09, 03:25 PM
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Exactly like that and exactly the way it has been for the past twelve years. In other words, the failure of both relays to activate the circulators and the burner occured before I disconnected the wires from the Zone 2 relay to replace it. The new relay went in with the wires positioned exactly as they were before. They were marked clearly prior to removal. Should I disconnect fro ZR & ZC to test if the circulators will run without firing the boiler?
 
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Old 06-21-09, 06:28 AM
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Update

The problem has been solved. The culprit turned out to be a bad line wire connection inside a wire nut inside a junction box. Arriving at that discovery was, of course, complicated by my assumption that the fault lay in the Zone 2 R845A relay and replacing it with a new YHR845A which refused to activate the circulator and fire the boiler.

I put the old relay back in, and all is right with the world again. I still don't know if the YHR845A, which was sold to me as a replacement for the R845A, is defective, or not designed to work with the R8182H Aquastat. Comparing the specifications of the two I can't find any difference, but who knows?
 
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