Furnace problem - Contractor Talk - Professional Construction and Remodeling Forum

01-07-2004, 03:58 PM

I have a problem with a natural gas furnace.

When I turn the wall thermostat up to make the furnace come on, it does NOT come on. If I do one of the following two things, the furnace comes on. 1. take out the fuse and re-install it. Or 2. remove the furnace front cover and replace put it back on (this allows the safety switch to come out and then be re-pushed in again, and this is what is causing the furnace to start). I tried installing a new thermostat but that didn't change anything except that I can now get the furnace to come on by turning the power off and then back on again at the thermostat. The heater works fine once it comes on but seems to need to be reset each time by cutting the power to the furnace and reestablishing it. I'm thinking there must be some part that is responsible for this that may need to be replaced. If anyone can can identify the problem and offer some advice on what I can do to fix it, I'd be very greatful.

Thank you,

Michael
Great Falls, Montana (20 below earlier this week)

hatchet · 01-07-2004, 07:48 PM

Right on.. I spent a couple years or so in Great Falls. My father built the 10th St (or Ave - been awhile) bridge and some others. I was about 6.. haha. I grew up in Superior, MT.
Anyway it sounds like you have a bad relay within the furnace that isn't reingaging. Bjd will probably have a troubleshooting method for you.

Michael · 01-11-2004, 03:21 PM

Quote:

Originally Posted by hatchet

Right on.. I spent a couple years or so in Great Falls. My father built the 10th St (or Ave - been awhile) bridge and some others. I was about 6.. haha. I grew up in Superior, MT.
Anyway it sounds like you have a bad relay within the furnace that isn't reingaging. Bjd will probably have a troubleshooting method for you.

Thanks Rich! I will try to contact Bjd about troubleshooting.

Bjd · 01-16-2004, 06:17 AM

By the design of the furnace that you are talking about, it sounds like it has a 3 way switch on the inducer motor. If this is the case durnig shut down it does not connect to tell the fan control to enter into post pure, this would cause this type of problem.
This design was created so as to prevent anyone from jumping out the control system, as in doing so would cause this problem.
By disconnecting the system from the power supply you are telling the control that it ok to restart.
Try to locate thei switch and either clear the line to it, or test the switch for proper operation.

Bernie

01-21-2004, 03:40 PM

Quote:

Originally Posted by Bjd

By the design of the furnace that you are talking about, it sounds like it has a 3 way switch on the inducer motor. If this is the case durnig shut down it does not connect to tell the fan control to enter into post pure, this would cause this type of problem.
This design was created so as to prevent anyone from jumping out the control system, as in doing so would cause this problem.
By disconnecting the system from the power supply you are telling the control that it ok to restart.
Try to locate thei switch and either clear the line to it, or test the switch for proper operation.

Bernie

Thanks for taking the time to offer your advice on this. Can you tell me where to look for this 3 way switch and how to identify it? Also, how do I go about "clearing" it?

Thank you,
Michael

02-26-2004, 02:48 AM

What brand what model ?