Gas boiler transformer blown
 

Hi. I replaced the old thermostat (Honeywell T87F) with a ritetemp
8022C. I have a Dunkirk Plymouth series II gas boiler (installed in the
last 5 years). The old thermostat was connected in a two-wire (R/W)
fashion. After I connected the new thermostat, I turned the power back
on to the boiler and nothing happened. Specifically, the power light on
the low-water cut-off did not come back on. In all honesty, I am not
even sure it was on when I first turned the power off as I didn't
really notice. However, none of the breakers are blown so I am assuming
there is power at least as far the 110/24 transformer. I know there is
no power coming out of the transformer as I tested the circuits. Does
anyone know a quick and easy (and safe) way I can test the transformer
and/or the incoming power. I tested the power switch and it is OK (no
resistance in on position, infinite resistance in off).

Any ideas or advice would be greatly appreciated. Thanks,

Gas boiler transformer blown
 

When you checked the Xfrmr, did you check it with the wires still
connected to the secondary? If so, disconnect the load on the secondary
side and then check the voltage. There could have been a short on the
load side which brings the voltage to 0V.
If you still get 0v on the secondary, but you get 110V on the primary,
then the Xfrmr is probably gone.

Gas boiler transformer blown
 

Mikepier wrote:
When you checked the Xfrmr, did you check it with the wires still
connected to the secondary? If so, disconnect the load on the secondary
side and then check the voltage. There could have been a short on the
load side which brings the voltage to 0V.
If you still get 0v on the secondary, but you get 110V on the primary,
then the Xfrmr is probably gone.

Well it turns out the previous owners had a contract with NStar that
was still in effect so we called them in. Then it turns out that there
is a trip in the circuit to the thermostat. No way to know if I tripped
it while changing the old thermostat or if it was already tripped
prior. Service tech reset the switch and we are set to go. In fact, he
said with the new thermo, there is no need for the trip as there is no
chance of overloading that circuit so he took it out.