Zone heating system (3 zones) - one zone is not working.

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Old 11-20-13, 07:08 AM
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Zone heating system (3 zones) - one zone is not working.

I have 3 zone heating system with Taco SR503 switching relay and 3 running circulatory pumps. Each zone is controlled by separate thermostat.

Today 1 zone is stopped working(not getting heat). I checked the SR503 switching relay indicator lights, the one zone has no light(no heat) but the other zones have light(getting heat).

What should I check first? It is a bad thermostat or issue with SR503 switching? Any diagnosis help would be appreciated.
 
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Old 11-20-13, 09:05 AM
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First thing always is to change the batteries in the thermostat.

If this does not help, with a small piece of wire you can place across the thermostat input to the 503 panel and this will tell you if the problem is in the panel or the thermostat/wiring.
 
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Old 11-20-13, 09:13 AM
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Does the NO lights on the SR503 switching relay indicate to the bad thermostat?
 
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Old 11-20-13, 09:21 AM
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If LED is not lit, the problem can be in the thermostat, the wiring from the thermostat to the panel, or in the panel itself.

The LED does not help to narrow the choices by much.

Placing a wire jumper across the T T terminals in the panel will narrow the problem significantly.
 
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Old 11-20-13, 08:20 PM
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Thanks…
I crossed the TT wire but no LED lit or heat. Since 2 other zone is working fine. what else it could be?
 
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Old 11-20-13, 08:33 PM
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If you jumpered the T T terminals in the panel and still nothing, then the panel would seem to be at fault. You've narrowed the problem to only one possibility by this test.
 
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Old 11-20-13, 08:49 PM
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Is the cube relay burned out. Did you try switching cubes with a working one.
 
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Old 11-20-13, 08:50 PM
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You mean the Taco SR503 switching relay at fault? If so, how come 2 other zone is working?

Do I need to replace entire switching relay unit to it can be repair with parts?

Here is the picture of switching unit:

https://drive.google.com/file/d/0B4I...it?usp=sharing
https://drive.google.com/file/d/0B4I...it?usp=sharing
 
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Old 11-20-13, 08:59 PM
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Thanks spott…
Yes, I tried switching cubes but no result.
 
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Old 11-21-13, 06:58 AM
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I don't think a blown fuse will only stop ONE zone from working, but I need to ask if you have checked that they are OK.

Please test one more time with a wire jumper across the T T terminals in the panel.

This time I would like you to turn ALL thermostats ALL THE WAY DOWN.

Carefully touch this wire jumper across EACH PAIR of the T T terminals for EACH ZONE.

I want you to do this to eliminate any question that you performed this test properly.

What you SHOULD see is that when you touch this wire jumper to a GOOD ZONE, the LED should light and the boiler should run.

Of course, when you touch to the BAD ZONE, you should have a negative result.
 
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Old 02-28-14, 08:52 PM
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heating zone 1 inop

i was reading this post and i have the exact same problem but when i jumped the TT to the zone in question the led light came on and furnace as well i changed out the batteries in the thermostat and it still will not work. after i confirmed that by jumping the TT in that zone what does that mean? wiring issue from thermostat to furnace? we just moved in this new place and it was working then it stopped after a week of living there need help you seemed to know exactly what the issue was for the other guy until the last post that is where i stopped need to know what else i can do to better isolate and find the cause thank you.
 
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Old 03-01-14, 07:54 AM
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Hi Eddie,

Let me see if I've got this straight...

You have a Taco panel; which one, what model?

You jumper the TT input on the Taco panel and the pump runs, the boiler fires up. This tells us that the panel is working and the wiring from the panel to the BOILER (we don't call hot water heating systems 'furnaces', but BOILERS) is OK.

Too bad Rah never returned... ppl do that for some unknown reason... never return. ???

You seem to have isolated the problem to either the thermostat or the wiring from the thermostat to the Taco panel.

You can test the wiring by removing the thermostat. Are there only two wires to the thermostat? If so, touch those wires together. If the boiler fires normally then the wiring to the Taco from the thermostat is OK, and the thermostat is at fault.

If the boiler does NOT fire, you know that your wiring has a defect, and the thermostat is 'probably' OK. (it could still be bad, but to have both the wiring AND the thermostat bad would be unlikely)

If you have another identical thermostat, you can also swap the two to determine if the problem follows the thermostat.
 
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