Cooked thermostat...Help

Garett

Garett

Cooked thermostat

Please help, I have a 24 volt thermostat a home that cooked itself. It was a White Rodgers 1E30-910. Replaced it with a Honeywell and if fried before my eyes. The small wire around the face on the front of the bimetal coil holding the mercury bulb burnt on both. I seems like extra voltage to me, but where would it be coming from?

The system is in floor radiant with valves on each loop on the manifold.

Thanks for the help.

Garett

jim lockard

Well check

Your voltage Maybe a control failed or the transformer did something odd. Garret I have seen 120v sent to a low voltage stat from bad controls before. On Goodman air handlers going thur the heat pak we had problems, with high voltage to the stats.=Miswire Best Wishes J.Lockard

Darin_5

T-stat less smoke

> Please help, I have a 24 volt thermostat a home

> that cooked itself. It was a White Rodgers

> 1E30-910. Replaced it with a Honeywell and if

> fried before my eyes. The small wire around the

> face on the front of the bimetal coil holding the

> mercury bulb burnt on both. I seems like extra

> voltage to me, but where would it be coming from?

> The system is in floor radiant with valves on

> each loop on the manifold.

>

> Thanks for the

> help.

>

> Garett

Darin_5

T-stat less smoke

Check for a dead short in the contol wiring between the t-stat and the load(gas valve). With the T-stat jumpered to simulate a call for heat, and no power on, look for a measurable resistance between your R wire that you will disconnect from the transformer and ground. If your resistance is really low(less than 5 ohms), you have a shorted wire to ground. Look for a staple or place here a terminal is touching something metal. I saw a thermocouple touching a terminal on the gas valve that could cause a situation like that. Hopscotching with one of the meter leads will help find the short.