Hi, my furnace went out yesterday. It responds to the thermostat, but starts up without any heat, nor the fan. I called a repair guy, he's amazed it still runs for it's age. But, for the ten years I've had. I've never had a problem with it. He believes the lies with what he called the "transformer". Black box, bottom left, bout 3" square x2.5". What do you think? And, is it possible to get parts for this model anymore? lol
Re: Furnace starts, but no heat nor fan operation.
If youe burners fire off it's not the transformer. It suonds like the fan/limit control. Try to turn the fan switch on the thermostat to the on position and see if the fan comes on, if it does leave it on and turn the heat on and see if the heat works that way. If so it would be the combination fan/limit control.
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Since you have two thermostats that operate the heating unit and the fan, and the fact that neither will turn the blower on, I would suspect the furnace/ air handler. Turn the thermostat to heat and see if the heat and the fan comes on, if it does operate normally in heat, the fan relay or the high speed on the blower is most likely the culprit. (If the furnace is equipped with a circuit board, the fan relay is integral to the board, if it an older furnace it has a separate fan relay). If it does not operate normally in the heating mode, verify power to the furnace, see if the flame comes on, if it does: the fan motor, circuit board or the fan relay are most likely the cause. hope this helps!
Hi Dave. I'm Roger. Its normal for a furnace to shut down completely when the set point on the thermostat is reached. The first and second stages are used when the temp. gets close to set point. The heat output drops to its low stage at around 3 degrees before set point. Check your owners manual for specifics on the fan though.
Most furnace operating on Oil or gas will heat the combustion chamber before starting fan to prevent cold air draft at start-up, can last a minute or two. Eiter the main flame does not come on or the chamber thermostat have fail. Try to modify fan option on room thermostat from auto to on. Cold air coming out: burner problem or no more oil or gas, warm air: burning chamber thermostat problem, leave room thermostat fan option to on until repair.
If there are no batteries in the thermostat then the furnace was being used to power it. To make sure it is just a thermostat problem, you can jumper the power and heat wires that connect to the thermostat, usually red and white, or terminals R and W. If the furnace comes on, then you need a new thermostat. If that doesn't work, you have lost power at the furnace somehow. If the breakers are good, and the furnace switch is on, then you can have a bad door switch inside the furnace, a bad transformer in the furnace, or a bad circuit board if equipped. If there is a circuit board, they usually have fuses somewhere on them too that can blow. Just be sure to cut power off at the breakers before checking. Hope this helps and good luck!
Depending on the model of the furnace, the blower is either a 2 or 3 speed. When the furnace operates in heating mode with the thermostat in the auto position, the furnace starts the fan when the furnace reaches a specific temperature or after a set time delay, but it operates the fan in low or med low speed on heat mode, when you put the thermostat fan switch in the "ON" position, the furnace operates the fan in "HI" speed, the same speed used for cooling mode. You may have a blower moter that is starting to short. I would recommend having a professional replace the motor before now before it becomes an emergency in the middle of the night during a cold spell.
It sounds like the humidifier may be improperly wired.
It's hard to solve without checking the wiring, but it seems like the humidistat is wired so that as the dial is advanced, it incorrectly turns on the fan, or furnace, or both. The contacts of the humidistat should be wired so that they turn on the solenoid only. Also, the power to the humidistat, to turn on the solenoid, should come on only when the fan is on.
Hope this helps!
I never liked the user un-friendliness of the Chromatherm, I would suggest finding a thermostat that you can understand and operate. Yes the Chromatherm is a good one, but so damned hard to figure out. Stay away from thermostats that still use mercury. Good Luck!