Hello All,

First time question and thank you in advance for your help. We had a storm blow through and we got home all was fine. 1 hour later bathroom light breaker was tripped and the thermostat was not working. We tripped our breaker and the bathroom light came on but no thermostat light. It was working fine when we got home storm was over, now nothing.

I replaced the t-stat and got nothing. I tested the wires and no power was coming. So I went to the contacter. The trip or bypass turned on the outside fan and unit. Power was coming to contacter. Nothing from 24V that was connected to T-Stat wire. I replaced the contacter. Still no power to the T-Stat :eek:

I am so frustrated :mad:

Can anyone help? :confused:

You really should not replace any parts until you locate the problem.

It sounds like the 24 volt supply for the low voltage circuit is not working. It could be a bad transformer or a small fuse located on the circuit board or in a fuse holder. Test the transformer and go from there.

It seem for some reason,, they first thing a lot of people want to do is replace the thermostat,,

The thermostat is the last thing I would replace. I might use a jumper or two at the furnace or air handler for elimination purposes. I believe they replace the thermostat because they feel comfortable with it since they see it all the time and it only has a few wires so it is not difficult to change. I would venture to say that 95% of all thermostats changed were changed for the wrong reason.

Usually the replacement thermostat will work worse than the old one because most people do not caulk where the wires penetrate the wall and that wall opening allows non room temperature air to hit the thermostat sensor and there goes the tight temp control.

All three of my thermostats here are 25 years old. They are the good old Honeywells that first came out with the adaptive recovery system. They have never been used as a set back unit but I like them because they have the best temperature control. I have about 40 different new thermostats sitting in the boxes but I have never been tempted to change to a newer unit. Since it has been somewhat cool this summer the board has not been that busy so that is good for all the folks to have less problems. I have posted this before but this is a actual picture from about 1973 of a set back system that was in use with a old coal stoker system.

Quote:

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Originally Posted by hvac1000

The thermostat is the last thing I would replace. I might use a jumper or two at the furnace or air handler for elimination purposes. I believe they replace the thermostat because they feel comfortable with it since they see it all the time and it only has a few wires so it is not difficult to change. I would venture to say that 95% of all thermostats changed were changed for the wrong reason.

Usually the replacement thermostat will work worse than the old one because most people do not caulk where the wires penetrate the wall and that wall opening allows non room temperature air to hit the thermostat sensor and there goes the tight temp control.

All three of my thermostats here are 25 years old. They are the good old Honeywells that first came out with the adaptive recovery system. They have never been used as a set back unit but I like them because they have the best temperature control. I have about 40 different new thermostats sitting in the boxes but I have never been tempted to change to a newer unit. Since it has been somewhat cool this summer the board has not been that busy so that is good for all the folks to have less problems. I have posted this before but this is a actual picture from about 1973 of a set back system that was in use with a old coal stoker system.

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I have an old thermostat like those round types but mine is square type. My question is how do I get the 18 or 24 volts on it so I can use the thermostat when the power gose off.. I have a Gas floor furnace and The thermostat will not work when the power is off is there any way I can jump it some how when the power is off to make the thermostat kick my furnace on thanks a lot

No your system needs the 24 volts for its operation. If you can find another sourse of 24 volts during a power failure then it might work.