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Re: Taco SR506 Switching Relay: thermostat Calls for Heat but zone not activated
" Does this behavior suggest the relays are fine? "
No, intermittent circuit connections are often agitated by vibration and/or heat. It could be the relay contacts or the solder joints and in a very rare occasion a defect or crack in the copper foil of the circuit board.
The relay is probably the issue, but solder joints fail too.
To bypass the relay. Turn off the power.
Remove the relay and insert a very thin wire (the thickness of the relay contact pin) into the socket OR in this case since I believe they are only using the NO contacts, if you can't find a thin enough wire to insert into the socket, carefully, securely rap a short piece of thermostat wire around the two relay pins up near the base of the relay (as illustrated below) and there should be enough of the pin left to make contact with the socket when the relay is re-inserted. The added wire should only touch the desires pins, touching the Coil pins would be bad since there is 120 VAC there !!!
Bottom view of the relay
The solder joints can be inspected rather easily. Turn off the power. Disconnect the thermostat wires, remove the nuts on the left side and gently squeeze the barb on the plastic stand-offs and lift the board just beyond the barb, when all the stand-off barbs are released the board can be raised off all the stand-offs and folded out with the AC wires attached. Or disconnect the AC wires too if that is easier for you. Inspect for cracked solder joints where the relay socket is soldered to the board.
109A_5
Re: Short cycling boiler. I'm stumped.
That's the backflow prevention…………..now required almost everywhere.
LRCCBJ
Re: Short cycling boiler. I'm stumped.
Open the feed first. After you finish all your purging, THEN open that valve.
LRCCBJ
Re: Short cycling boiler. I'm stumped.
Have no worries. It will stop at 15 psi.
But, then you'll need to purge it and you'll need more than 15 psi at that time.
LRCCBJ
Re: Merry Christmas, Happy Channukah' Seasons Greetings to All
Merry Christmas, Matt and to all on HH. Happy Healthy New Year to all. Happy
I can't believe it will be 2025.
Yera 2000 when everything was supposed to crash seems like yesterday now 25 years ago
Re: Short cycling boiler. I'm stumped.
If you used pipe dope, it doesn't dry like that. An epoxy putty might seal it up for a while, but you'd have to clean it pretty good to get it to adhere enough to hold back water.
ratio
Re: Taco SR506 Switching Relay: thermostat Calls for Heat but zone not activated
I am thinking that one of the relays on that board are acting up. there are seven 24 VAC coil relays and one 120 VAC coil relays. I believe the one with the metal strap all the way to the left is the 120 VAC relay
Grainger sells the replacement relays for that board. Grainger # 6C875 is the 24 VAC one. Grainger # 6C876 is the 120 VAC coil relay. But it has been so long since I worked on that older model. I can't be sure if my information is current. I thing one of the 2 relays on the left are the problem. and it looks like that problem has happened once before and someone robbed zone 4 relay and swapped it to fix a problem in the past. Just a guess.
If you can give up one of the zones for now and you take a zone relay out and swap it with the second from the left relay, you may solve the problem. Then you can order the #6C875 from Grainger to replace the failed relay.
@SteveSan From TACO Tech Support is on here regularly, and he will know if one of those relay cubes will solve the problem you are describing.
