25 year old York gas furnace. I've always wondered about the limit stop on my limit switch. It's set at 160, tho all the pictures i've seen show the setting at 200. Any reason mine is set so low? Wouldn't I get my house to heat up faster if it was higher? http://imgur.com/HVCOqUL
Posted Nov 9, 2015, 6:28 PM UTC
How many btuh is your furnace?
76,000
Is that input or output? My guess is output. 150 Is the limit for a lot of 80% 100k btu furnaces . Any higher and it could lead to catastrophic failure of your health. I don't see too many low efficiency furnaces that age still running like a top. Usually there are breaches in the heat exchanger and the ribbons are dirty and rusty. Most people will turn the high limit up to compensate for bad air flow from a dirty blower or evaporator so they can have consistent heat however unsafe.
input btu/hr: 76,000 http://imgur.com/5Nzngu7
Your designated temperature rise is 45-75 degrees F. So if it's 70 and the unit is running your max outlet temp should be 145. So 160 is a good spot for your high limit to be set at. Does the gas ever quit running before your thermostat becomes satisfied?
The limit is set for different models and different BTU sizes. The same model but a different size will have a different setting. Leave it.
It won't heat up faster, unless the temp is going high enough to trip the high limit, which will shut the heating down. Does the furnace ever shut off while it should be heating? If it does you have a problem. If not, if you don't have any problems, I wouldn't change it.
well, it does hit the limit on a regular basis...gas turns off, fan continues to blow, after it cools off a while, gas turns back on...repeat.
Call for service. Start planning for replacement.