Burned Out

Supply House Rick

If it does it w/ only the gas valve connected, w/ multiple transformers and stable line voltage then something in the gas valve is intermittently drawing too much power (much more than 40 VA), dragging the transformer output down, which then probably is causing the gas valve to drop out.

Maynard

Found Burned Out 24 Volt 40 Va Trans On Gas Boiler Today.
Found And Repaired Shorted Wire From Thermostat. Replaced Trans.
Boiler Runs 5 Minutes Then It Starts Short Cycling.
Trans Has 27 Volts Until Short Cycling Then Drops To 14 Volts.
Tried Another Trans...Same Results. Voltage To Trans Fluctuates From 120-123. Switched To other Leg Of Circuit Box...125 Volts Steady. Same Voltage Drop At Trans Secondary.
I'm Stumped...Any Thoughts?

don_201

Did

Did you disconnect the load on the secondary side and check voltage right at the transformer?

It sound like you have a safety thats either doing its job or its weak.It could still be in the tstat wire.

Try bypassing the stat and tstat wire and used a jumper at the boiler control.

Maynard

Jumped Out Every Safety And Controls Including Thermostat.
Ran Wires From Trans Directly to Gas valve And Same Situation with Voltage Happened?

Unknown

I'd suspect,,,

the gas valve at that point. Try running a relay off your truck with the existing trans, if it works ok the GV may have a short in the solenoid coil or something.