Anyone with HVAC or Knowledge Regarding Installing a Common Maker?

[Burnin Since 1991]

Strike 1... The two T connections are on a board as is the step down transformer. Pics attached. What is involved in installing a separate transformer? I have plenty of 120v access in the boiler room.

 

[Burnin Since 1991]

Here's what I am looking at 120v - 24v ac Transformer

If my thought process is correct, I can connect the transformer to 120v at L1 and L2 using the Positive Black Wire and Neutral/ Common White Wire on the transformer and on the 24V side the Green is Common/ Neutral for the C-wire. Do I need a connection to the Positive/ Red Wire of the 24v transformer?

 

[Burnin Since 1991]

or this plug in transformer

i would need to add a box and outlet though.

 

[Whitenuckler]

Strike 1... The two T connections are on a board as is the step down transformer. Pics attached. What is involved in installing a separate transformer? I have plenty of 120v access in the boiler room.

View attachment 350183

If your thermostat will take an isolated power other than the power to operate, you could do it using two new wires plus the originals and a transformer. If you can find relay (1k) coil on the board, you can trace it back to the transformer secondary and T terminals. Then tap into the correct side of the relay coil.

 

[Burnin Since 1991]

If your thermostat will take an isolated power other than the power to operate, you could do it using two new wires plus the originals and a transformer. If you can find relay (1k) coil on the board, you can trace it back to the transformer secondary and T terminals. Then tap into the correct side of the relay coil.

My request to pull the board for further inspection has been denied by my employer (my wife and her sister) I will have to make do with the transformer. It does say it's compatible with my brand of thermostat.

Upon further investigation, the Black and White Thermostat wires connected to the T terminals go up to the zone valves. The black and white coils (from the boiler T Terminals) go to the B Zone valve on 2 and 3. The black wire on 1 goes to the B Zone thermostat. The other Red wire on B zone Valve 2 goes to 2 on the A Valve. The White wire on 3 of the B Valve goes to 3 of the A Valve. The Red wire on 1 of the A Valve goes to the A zone Thermostat. The white wires on the transformer goes to the zone B & A Thermostats.

Sorry about the pics. Did the best I could.

Hoping I can connect two wires from that transformer? Or do I need another one? It would be one to RC and the C wire. On my old school thermostat the black wire was connected to RC and jumped to RH and the White is on W. I believe the Sensi thermostat is looking for a W, RC or RH and a C for a zone boiler.

 

[gthomas785]

Ok forget the boiler control. Whichever transformer is powering R on your thermostat, th C wire needs to come from the other leg of that same transformer winding.

 

[gthomas785]

I can not tell for sure from your description but it sounds like your red and white wires to the thermostat are backwards from usual. Normally red is hot, and white is switched.
Whichever one is currently coming directly from the transformer should be connected to R(h), the one going back to the zone valve goes on W, and the new common going to the other transformer terminal should be on C.