Furnace help please...


I have a Heil brand gas forced hot ait furnace. It comes on & heats up, but doesn't blow hot air in the house. The blower comes on, but usually doesn't blow very hot air.
I had a tech come out four times. He said it is heating up to the right temp of 140 degrees. He replaced the fan control switch, and then the electronic thermostac. It is still doing it. Now he says that we do not have enough vents and wants to run another return.
The problem I have with that is the furnace is 10 years old and we lived her 4 years. It was never a problem before. Until this winter it would get very hot. I'd be swetting at 75 degrees. Now it feels cold and damp at 75, if it even reaches that temp. I'll have it set for 78 degrees and it will never show more than 69 or 70 at night. During the day it gets warmer, but I think that's from the sun coming in the windows.
Could sombody please share an opinion of what to do. It's going to start getting colder at night here in New Jersey. Thanks.
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snipped-for-privacy@aol.com wrote:

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you may need a more experienced repairman. or perhaps at night there is something different in the home like a broken window. meanwhile, these links have proven excellent to me. see: http://www.misterfix-it.com/Solutions/5Air.html see: http://www.arnoldservice.com/Troubleshooting_Heating_Problems.htm see: http://toad.net/~jsmeenen/wiring.html see: http://yourhome.honeywell.com/yourhome/Applications/Wizard/Wizard.aspx
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Could be a lot of things. But I'd start by looking for a main trunk of the duct system having come loose, or some significant source of cold air infiltrating the house that wasn't there last year.
The technician appears to have ruled out most issues with the actual furnace itself if the heat rise checks out within spec.
Best Regards, -- Todd H. http://www.toddh.net /
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wrote:

If you have 140 degrees coming out of the furnace and 69 to 70 degree air going into the furnace then this suggests that your rise is wrong. Most furnaces have a maximum rise of 65 degrees, yours is 70 degrees. If the temps you posted are indeed correct then your rise is too much. This suggests that the system may be cycling on the high limit control. This can be caused by several things. I would suggest you find a competent tech to diagnose it since the one you have is a parts changer, not a tech.
http://www.thehvacmedic.com - All the free heating and air answers you want!
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Al Moran wrote:

That doesn't sound right to me. My furnace is spec'd for 55-85 degree rise.

That doesn't sound right to me. 140 seems too low for a limit setting. I would think something like 160-180 is more in the ballpark.
This can be caused by several things. I would suggest you

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wrote:

I think sometimes an existing vent will shrivel up and disappear, especially if the heating technician has more bills than money.
It's an insufficiently researched economic phenomenon.
He shouldn't have replaced the thermostat, iiuc. There was no basis to do so. What problem was he hoping to solve by replacing the thermostat? Let him explain that to you. If the furnace went on and the fan went on, the old thermostat worked. Thbat's all the thermostat is supposed to do. Right, guys?
He should reilnstall your thermostat and take that item off the bill. If he doesn't have your themostat anymore, he should still take that item off the bill -- unless someone here contradicts me. I guess if he claims not to have yours anymore and insists on putting on someone else's used thermostat, I'd take it, but only if I got 100% return of the parts and labor that he charged you for the new thermostat. Check with others here.

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