thermostats with zone valves

[Deleted User]

my cousin is a plumber and he had a frozen pipe call and found no heat to the room.thermostat smelled burned so i pulled it and found 2 TT wires on each screw?can you hook 2 TT together does that make sense.don't know for sure they go to the other thermostat though.anyway when i put a jumper on the 2 screws it really sparked like to much voltage and it blew the transformer.there is 2 zone valves with one taco operating control.could the wiring be messed up. thanks mike

Josh M.

Sounds like you have both common and hot going to the t-stat if the transformer blew. A thermostat is just a modified switch. Generally you are bringing hot in one side and out the other to energize the zone valve. See if you can trace the colors back to the transformer. I have never used taco zone valves though.. So I couldn't tell you what needs to happen there.

Mark Wolff

If it ain't broke...

How long again had this system been working before the pipes froze?

Anyways, there are two systems on the taco zone valve, based upon three terminals. The center screw is the common for both systems. The top terminal is positive (load) from the transformer via the T-stat (load out to red on t-stat, white on t-stat to top terminal on ZV head. The power leaves the zone valve head through the center terminal which is neutral (negative) and goes directly back to the OTHER terminal of the transformer. There is ANOTHER power lead going from the transformer LOAD terminal to the TT's on the boiler, then to the bottom terminal of the ZV head then back via the SAME neutral center wire.

If you have two wires on each terminal in the tstat, it is possible they ran double wire either due to undersizing (using phone wire instead of tstat wiring) or they wanted a redundant wire in case the other broke, or they didn't know how to wire the system in which case it probably wouldn't have worked in the first place.

It sounds like the zone valve head went bad, thus freezing that zone, then when you shorted the circuit (with a screwdriver I presume!) you overloaded the transformer (they are VERY VERY VERY sensitive) blowing it.

If you put a new transformer and zone valve head on you should find the system functioning normal again.

[Deleted User]

TT

changed out the head and transformer also thermostat that fried.everything seems to be working ok now.there is a TT wire going to a argo single zone control that runs the circulator for those 2 zones that may be where the other wire comes in. thanks mike

eleft_4

thermostats with zone valves

Depending on the design of the thermostat, one powered wire for tt the other to power anticipator coil.
Don't know how a quick short out can burn a transformer???

al

Steve Eayrs

All it takes is one small spark..........

to let that there factory installed smoke out.

Steve