gas furnace just isn't heating the house?

Question

We have a Payne Plus 90 gas furnace. It just doesn't keep the house warm anymore. A couple of winters ago, we had this problem and the service man told us that it isn't designed to operate below 25 degress. It sits in the garage. That sounds crazy. This winter, it isn't working well either.

So what happens is that it turns on, and only runs for maybe 6-8 minutes before shutting off. It might be hours before it comes back on again. We are calling someone to come out next week, but I am just wondering what we could possibly check for this weekend to get it going.

We checked the water drain trap, and cleared it. It did not have a clog or build up of water.

We replaced the thermostat in the house because we first thought it just wasn't sensing the right temperature. The replacement one has a digital thermometer, and it is right, it is like 65 degrees in here! brrr
thanks

Answer 1

If I were you I'd read the directions for the thermostat from front to back.

All thermostats have some sort of a "deadband" built into them. This deadband may or may not be adjustable but it's purpose is to keep the furnace from cycling on and off too frequently. The deadband could be as little as 1 degree or much higher if it is adjustable. The deadband makes sure that the temperature falls to a point below the setpoint prior to starting the furnace. The furnace will then bring the temperature up to the set point before shutting off.

Since a 90% efficient furnace condenses water it is likely that the reason for the 25'F minimum temperature limit is due to the potential of freezing water in the condensate outlet line causing the heat exchanger to fill with water and create backpressure causing a dangerous high pressure situation in the firebox of the heater. They are probably conservative when they specify 25'F because they don't want to take any chance of creating this situation and possibly having a fire or explosion caused by there piece of equipment.

I'd heed the warning.

Good luck!

Answer 2

well, a furnace can be fuled in may ways. methane, (gas), LP gas, electric, steam, or a heat pump. furnaces can be low efficiency or high efficiency. considering the cost of energy, you should ask about a high efficiency furnace. these are usually natural gas furnaces. BUT if you live in a milder climate a heat pump would be your best option. electric heat is very expensive. i like it and have it in my house BUT it's not the way to go on a new system. that is unless you want to pay for it. every time an electric heater kicks on, it's 15000 watts of power, (3 5 KW heating elements). i would consider a high efficiency gas furnace OR a heat pump. GL with it! jim TERMS: BTU's, heat pump, high, low, medium efficiency, heat exchanger, plenum, watts, kilowatts, (KW's), amps, LP gas, natural gas, ducts, SEER, (seasonal energy efficiency ratio), load calculation, indoor blower motor, air handler, pilot light, igniter, filter, CFM, (cubic feet/minute), and other stuff. learn what all that means though and you can talk like a pro! i've gone this far, i might as well finish the discourse. a heat pump uses the principals of refrigeration in reverse. it turns the AC unit into a furnace. it uses a reversing valve to turn the condenser coil, (outdoor coil) into an evaporator coil, (indoor coil). SO, the outdoor coil absorbs heat form the cold outside air and releases the heat into the living space through the indoor coil. NOW, you can see why this system doesnt work well in really cold climates. the outside air is too cold and there is no warmth to absorb. SO, heat pumps are only good in milder winter climates. now, you may say ok, but the compressor is running all the time, winter and summer. what's up with that? heat pumps use really good compressors called scroll compressors. it's all good. moving on to a high efficiency gas furnace is the next thing. these things are amazing 98% efficient. they use 98% of the BTU's available from the fuel supply. this is accomplished by condensing the hot exhaust gasses that would normally be released out the flu pipe. ok, i've given you boo-koos of good info here. i hope this helps you make your decision. I AM OUT!

Answer 3

The furnace lmust be sized to the house, insulation, wndows, number of occupants etc. That is called a heat/cooling analysis. Find a HVAC that understands how to perform the analysis. they can then provide the proper size furnace and blower to do the job. They should also check the duct work and make sure it is the proper size to move heated air to the rooms. Payne furnaces are fair but not anywhere the top of the line. They are known as budget units or builders models.

Answer 4

Coach makes valid points,but, sometimes the thermostat is simply installed in the wrong part of the house. Ideally, it should be near the return,which should be in a common area. Not on an outside wall,but away from outside doors. Also not too near the kitchen.
Otherwise, you could check to see if any of your ductwork has come loose or been chewed up by varments,dogs etc.
BTW, 90 plus is just your efficeincy rating, what will determine if you're properly sized for your house is the BTU rating.
Good luck with everything.

Answer 5

Your repair man is right, the furnace will not operate in those cold conditions. Your furnace is a condensing furnace and that means it has water inside of the secondary heat exchanger, all the tubes, hoses and the trap. Simply put you have water freezing with in your furnace. You have a few options 1) move your furnace to a conditioned space. 2) condition your garage. 3) isolate your furnace within the garage (build walls) and add a register to your plenum to keep that room conditioned. You will see a big difference.

Answer 6

You have, or should have, two thermostats in the furnace, usually against the plenium wall. these control your high and low temp input and output.
These have to be adjusted or replaced by a serviceman, don't mess with these yourself. This is probably where the problem lies.
One other place is the thermocouple that's not working right but, usually they just go out and that's it. You can try replacing it but, you might be throwing your money away. It's best to wait for the "man" to come around and do it right.

Answer 7

See if you have a clogged filter. If so, air doesn't get through fast enough and the bonnet overheats. The overheat safety kicks in.

The fact that it won't come back on for a long time makes me think that one of the overheat safeties is haywire.

Answer 8

Check the thermocouple on your furnace. Insulate your windows to keep drafts from coming in, and, also, you can use a space heater to add warmth to your home.

Answer 9

sounds like its sensing overheating of the furnace itself. filter & ductwork clear?