Taco sr503 one light off, one zone cold

KristenFT

Hello,

First time home owner, trying to troubleshoot a problem. I have a hydronic system (tagged antifreeze) with a Weil-Mccain WGO oil boiler (2013), 3 zones, Taco sr503 zoning control, Honeywell L8148A,E Aquastat relay.

PROBLEM: One zone the baseboards are cold (very cold) and not heating (was working 3 days ago), other 2 zones work great.

I look a look and the red LED light on the Taco does not come on when the thermostat should trigger. The green power light is on and the 2 other zones are red. I thought maybe it was the thermostat so I opened it up and found two wires one white one red, both tightly screwed down. I changed the face plate with an identical one from another zone, Zone 1 thermostat worked in zone 2, so that I think eliminated the possibility that the thermostat was the problem.

If I make the thermostat “call” for heat and the red LED does not light on the Taco zone switching relay is that a definitive sign that my problem is the Taco zoning control? Is there a manual way for me to bypass this zoning control to get the heat on?

Any crazy chance that one of the pipes in this zone had a spot freeze (runs under sunporch) and that stopped the circulator pump which “told” the zoning control that it can’t be triggered?

Thank you!

BPH

Is the pump energized i.e...power to the pump?

KristenFT

I believe I have 3 taco cartridge circulator pumps, one for each zone. I'm not sure how to check if I have power to each pump.

BPH

Do you know how to use an electrical meter?

GW

If the light isn't coming on I'd look at the thermostat first. Batteries good?

Zman

The green light means the t-stat is calling for heat and the controller is trying to open the zone valve. The red light means the zone valve has opened.
It sounds like a bad zone valve. What kind is it?

KristenFT

No, but I could read about it, I can pick one up tomorrow if that would be helpful. All I have is voltage detector. I'm guessing the pump has a cover I can pop off to test if it has power?
Thanks!

BPH

It's an sr not zvc.

BPH

You might think about getting a tech out there.

KristenFT

This is what I got from the Taco manual

"External Diagnostics:
Externally visible lights show full functionality of the switching relay. The green light should always be on, indicating that power is connected. When the thermostat calls for heat, both the appropriate circulator and red indicating light is energized."

KristenFT

I did change the batteries and even switched the thermostat with an identical one from another zone. I can get this thermostat to trigger the red light, pump, and get heat when used in one of the working zones.

GW

Sounds like a dead thermostat, of that relay inside the SR is dead

If the zone light isn't coming on dont worry about the circulator, worry about getting that light to come on.

BPH

Correct...you need to verify that the t-stat is working that means verifying both the stat and or the TT connection on the controller are doing there job, next if they are.... is the pump getting power if not it's the controller if it is it's the pump.

oreo123

My guess is thermostat is not calling. Are there good batteries in it?

KristenFT

Thanks for all the advise. Turns out it was a frozen pipe.

Joe Mattiello

Good morning Kristen
I was reading through your tread, and happy to hear you found the problem, and it wasn't the Taco control Heatinghelp.com is an awesome resource. For future reference, you can also contact Taco directly at 401-942-8000 and ask for tech support. It's always best to call when you have access to the control, so we can try some troubleshooting diagnostic exercises to isolate the issue.

megenedr

My system went down overnight and the green power light is no longer illuminated. I confirmed there is power at the 120v terminal. What could be my issue?

Jamie Hall

Check the fuses on the board. If one of them is blown, find out why before you replace it...

Alan (California Radiant) Forbes

Back to Kristen's original problem, the red light should have come on when there was a call for heat regardless of frozen pipes, no?

Melissa2316

Can anyone help?? Also first time home owner. Zone two and three are red. No heat on either floor. What should I do? Any help is much appreciated 

Melissa2316

STEVEusaPA

Shut off power to boiler and relay. Change the batteries in the thermostats, turn relay/boiler back on.
If that doesn't work, call someone.

Melissa2316

Turned it off  and back on still doesn’t work. No batteries in the thermostat. It Hard wired in the wall. Tried calling .. can’t get ahold of anyone Sunday in New England. Had to be one of the coldest days this happens on

Alan (California Radiant) Forbes

Do you hear the pumps running? What about your boiler? Is it turning on at all? Show us some pictures of your boiler, piping any any pressure or temperature gauges.

Melissa2316

Hello Alan, thank you for responding. It’s definitely igniting and I haven’t had any troubles with my hot water. The two zones pumps were cold last night but I felt them running. After all the YouTube videos I decided to turn down the thermostats all the way last night and go back at it this morning. This is what I seen this morning. Seems that I only have one red light On the Taco box when Turning the thermostat back upin

SteveSan

Please call into Taco Tech Support @ 401-942-8000 ask operator for Tech Support. We are here Mon-Fri 8am-5pm EST. Please have access to sr control to help troubleshoot.