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klaus135 12-10-2012 04:47 PM

Furnace not getting past 76 degrees
I have a rental house and the tenant is complaining the furnace isnt putting out enough heat. They keep the thermostat at 90 and it doesnt get hotter that 76. Which is of course out enough, but thats besides the point. Its almost like theres a governor on it that wont let it get past that. Is there a part that is bad?

beenthere 12-10-2012 05:04 PM

Check air filter, it could be dirty. Also, if it has central A/C make sure the indoor coil is clean. the furnace could be tripping out on high limit. Its a safety device that prevents the furnace from over heating.

Might want to see what blower speed it is set to. if its not on high, switch it to high.

joecaption 12-10-2012 05:08 PM

Unless there breding sheep in there, there's 0 reason the tempature needs to be any higher then 70. Most people this time of year keep it about 68 to save money.
Tell them to go pound sand.
Who's paying to the heating bill?

how 12-10-2012 05:11 PM

The only person I can think of that would try to get a home above 76 degrees is someone who isn't paying that heating bill. New tenants needed.
You sure about those temps?

joecaption 12-10-2012 05:16 PM

Sure there not trying to grow Pot in there?

oncall 12-10-2012 05:19 PM

I agree why would they need to heat there house above 76?
Maybe they are leaving the windows open?
Does the furnace shut off at 76?
How old is the stat, is it a mercury switch? Maybe the stat is not level.

If I had a tenant that heated to 90 I would make sure the bill is in their name.

Not trying to belittle anyone, but if they can heat to 76 I see no reason to to have to make it warmer, unless they are very sick and need an incubator for a house..

klaus135 12-10-2012 05:34 PM

With the exception of "beenthere", you all missed my point. I do apprieciate the responses, however, I stated how hot they want it isnt the point. The point is, its not getting hotter. If the thermostat is set at 90 for a week, shouldnt it reach 90 inside the house? If I set my own thermostat at 90, I think it would get to 90 without shutting off. Or at least run continuesly as it would try to reach a higher temp. NOT that they want it at 90....but appearantly they want it hotter than 76. I am not paying the bill, they are not growing weed, they are afro-americans who do not like Chicago winters!

oncall 12-10-2012 05:41 PM

Was anything done with the furnace?

1. was the furnace motor change ? It could be spinning backwards and/or not throwing that much air.
2. Was the anticipator ever checked or cycle setting depending on the stat, ever ajusted for your furnace.
3. If a mertcury style thermostat is it level.
4. Is the gas pressure on the manifold set correctly usually around 3.5"w.c. pressure

I would suugest you might need to call a HVAC guy he can check these things out.

These are some Ideas for you to check. Hope this helped.

how 12-10-2012 05:44 PM

If you provided info like....
the main gas is cycling on and off with the blower running continuously but the temp won't rise above 76 then folks would suggest a temp rise test on your furnace. Is the limit control doing it's job or not? Dirty air filters or a/c coil? Thermostat continually calling for heat?
Distribution size too small? Furnace too big? Home insulation and type of windows? Etc.

jagans 12-10-2012 06:06 PM

New Tenents
Are these new tennents that want it hotter than any of the previous tennants ever wanted it? Maybe the furnace you have has never been able to attain a temperature higher than 76. Does it turn off at 76? or did you mention that.

klaus135 12-10-2012 06:43 PM

It's a digital thermostat. They were there last year. The one guy sleeps in the basement. But i looked at the furnace yesterday. It was set at 90 then just stops. It will restart, but stops again. Sometimes the blow is just on blowing air without the furnace kicking on. O changed the air furnace guy just looks at it and says It's fine.

Missouri Bound 12-10-2012 06:56 PM

The furnace guy is wrong. I think the furnace needs a thorough examination, as already said by Beenthere. And get a new furnace guy.:yes:

jagans 12-10-2012 07:58 PM

You did not mention whether there was an evaporator coil in the plenum above the heat exchanger for AC maybe it is filled with crud and the furnace is shutting down. Also, are they jacking the temperature up in an attempt to get some heat to the basement guy? Maybe cut a duct or two in down there for him? I would advise to have a good HVAC Tech give the furnace a really good cleaning, then go from there.

ben's plumbing 12-10-2012 07:58 PM

did you try bypassing t stat...see if furnace continues to run with another thermometer to measure temperature..ben sr

Technow 12-10-2012 08:26 PM

70 is standard design conditions for any heating system.

In the field, hooked to real ductwork, many furnaces are at their temperature rise limits at 70. try to go above 70 and now you are pushing the HI Temp limit and it starts cycling off.

What is the temperature rise of the furnace? You can't have a furnace raise temp to 90 because that will probably trip the limit.

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