Low voltage circuit problem. Thermostat works, zone valve works, no call for heat.

donaldmc

But if I jump the TT in the Hydrostat the boiler fires up!?
I replaced the zone valve motor, checked all the low voltage wire nut connections(also soldered them), I have 24V at the transformer, the thermostat is working -every thing is fine for 2 to 3 days then the same problem again. I'm perplexed!
This is my third call to this unit for this same problem. Any help would be a blessing!
6 month old Biasi boiler with a NX burner, Hydrostat 3250-plus, Taco cirulator and zone valve.

megajennyposts

Getting help with the thermostat. Thanks for the installation method.

donaldmc

Problem solved! Called the Hydrostat people-swapped it out- fixed. Still under warranty so I don't have to pay! All's well that ends well......the end switch in the zone valve was bad too. Hence the problem trying to diagnosis it.

Steamhead

Which Taco model zone valve?

donaldmc

Honeywell 24v zone valve model #v8043e. The end switch was working intermittently, make diagnosis difficult.

Steamhead

OK- that has a completely isolated end switch. Some Taco and B&G ZVs (and possibly others) do not, and if hooked up wrong they can burn out transformers.

donaldmc

Thanks for the info!

rick in Alaska

Why did they replace the aquastat if it was the end switch on the zone valve? Are we missing something else?
Rick

Tinman

Agree w @rick in Alaska. Jumping TT on the aquastat brought the boiler on.

donaldmc

The Hydrostat 3250 plus was giving a "code" when energized -I do not remember what it was- I was told by the tech at Hydrolevel to replace it. No cost, still under warranty.
Installed replacement - no code when turned on...