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! brrrthanks
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!
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.
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.
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.
