Gas and Oil Home Heating Furnaces - Proper setting for limit switch?
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : Proper setting for limit switch?
Erb
12-21-04, 05:54 PM
The limit switch on my gas furnace has an adjustable arm that appears to be able to set it anywhere from about 150 to 250. It also has an Off setting. Right now it is set about as low as it can go. Is there an ideal setting? I have been having occasional problems with the gas burners shutting off and the blower running for extended periods causing the house to get quite cool.
Thanks in advance.
Thanks in advance.
mbk3
12-21-04, 07:02 PM
What brand furnace and age? Are you talking about fan switch or limit switch or both?
Jay11J
12-21-04, 07:48 PM
When you look at the limit dial.
the first set of peg is your "off".. That should be set around 80 to 90...
next set is your "on" peg. I wouldn't set this any higher than 120..
last peg on the far right, is your limit. most of are set around 200.. Some times there a stop to only let you set it so low.. Set it low as you can.
the first set of peg is your "off".. That should be set around 80 to 90...
next set is your "on" peg. I wouldn't set this any higher than 120..
last peg on the far right, is your limit. most of are set around 200.. Some times there a stop to only let you set it so low.. Set it low as you can.
Erb
12-21-04, 08:18 PM
There is only one peg on the limit switch in this case. It says "off" on it and it is set around 170, which is about as low as it can go. It looks like it can be set as high as 250.
mattison
12-21-04, 08:27 PM
That's different but apparently it's a high limit. All that's going to do is shut the system down if the temp gets to high.
Can you link to a picture of what you've got?
Can you link to a picture of what you've got?
Erb
12-24-04, 06:38 AM
I had the problem again last night. Gas and flame shut off but blower kept going. This time I caught the diagnostic light. It was blinking 5 times, which the legend said meant "rollout open". What is the rollout? Do I need to open or close it? How do I do that? Thanks a lot for your help and Happy Holidays!
Jay11J
12-24-04, 01:13 PM
The "roll out" is a safty control to turn off the system if the flame is rolling out of the burner area.
if this is happing, you have to check your heat exchanger, flue/vents, and flame.
if this is happing, you have to check your heat exchanger, flue/vents, and flame.
scottg
12-24-04, 07:16 PM
Yep sounds like a crack in the heat exchanger.
Big trouble !!!!!!
Big hazard !!!!!
Have it checked real soon.
Big trouble !!!!!!
Big hazard !!!!!
Have it checked real soon.
coldmechanic
12-25-04, 11:35 PM
sometimes the rollout switch just gets dirt on it. power it down and pull it out and give it a good cleaning and see if it works again.