Heat temperature issues with Goodman GMP 100-4 furnace
The problem that i am having is that the furnace blows around 92 degree air. It cycling and getting my thermostat to temperature. I have extra thermometers sitting all around my house and i have confirmed that i have about a 3 degree temperature drop from shoulder level thermostat to floor. When i raise the temp on the thermostat the furnace will blow much warmer air(around 130 or so) until it gets the thermostat there and then cycle off. Then the cycling from there on to hold that temperature goes back to the cooler air unless i raise the temperature so more. When that cooler air i can never get from about waist down to heat up. It always does heat up when that warmer air is blowing, but it doesn't do it everytime the furnace comes on, only when i raise the temp. Hope this makes sense to someone. I have only been told by a professional that my unit is undersized. They said it is 69,000 btu's. My house is 2000 square feet of conditioned space. I use propane and propane alone is costing $300 per month and i am still not comfortable. Thanks so much for your time.
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Re: heat temperature issues with Goodman GMP 100-4...
69,000 btuh is adequate for a 12-1400 square foot house.
Otherwise, your thermostat simply tells the furnace to cycle on/off.
If it calls for heat and does not come on, the problem is with switches and relays within the furnace.
Your setting the temp higher only causes the other parts to keep trying until they finally light and heat.
This is based on your information saying it will cycle on and blow cool air--not hot air.
You will have several temperature variations from floor to ceiling.
You probably have ceiling vents as well.
You need a technician to verify the rollout switches, fan relay, inducer fan etc. if the furnace is not firing everytime you call for heat.
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A heat pump on the optimal heating day (about 50 degrees ambient) will only deliver approximately 85 degree air as compared to 125 degree air from a fossil fueled furnace. The colder the outdoor air is the less heat there is available to be transferred to the living space. At 30 degrees, the heat transfer capability is getting close to negligible meaning the run cycles will be approaching continuous and eventually as the heat pump along cannot maintain setpoint, the outdoor stat or stats will bring on auxilliary heat in the air handler.
If your ambient temp is below the 'balance point' of the heat pump, the house temp will drop a little lower and most times energize the heat strips through the outdoor t-stat. Your outdoor stat could be set too low for the heat pump to carry the structure all the way down to the balance point so when you turn it off and back on, the lower indoor temp automatically brings on the heat pump plus a heat strip or two, thus the warmer air. Second stage on the stat satisfies due to the heat strip, drops them out of the circuit and the heat pump is left running on first stage heat delivering the perceived cold air.
Your outdoor stat could also be not functioning correctly and not allowing the heaters to come on until the system is turned back on reestablishing the two stage call for heat.
Tons of possibilities and not enough room to list....
The fan relay is stuck in the on position. When the temperature drops the heater does not ignite because the fan is already running and ignition is locked out after the heat cycle starts an the fan turns on
blowing cold air on this furnace usualy caused by high limit trip, or flame roll out. the first one, (high limit) is from insf. air flow. (blocked filter,bad zone damper?
The second,(flame roll out) caused by bad heat exchanger,blocked vent.ect.
check out the fan switch on the unit and make sure that its the correct one. it should cycloe on @ 120 degrees and cycle off around 100 degrees. Someone may have put in a different one and that is not the approve one.
heat pumps generate heat from compressing freon and take a while to generate enough heat to be useful. never expect robust heat from a pump like an oil burner or a gas furnace, but they do heat great and are cheaper to operate. do this . if you are still using an old mercury bulb stat change it to a digital one. this will hold an exact temperature and time off between cycles will be less and the indoor coil will stay warm between short cycles, with an old mercurry stat you set it at 70 and it may run up to 73 and stay off till 68. thats a long off cycle and when call resumes the coil has gotten cold and has to start all over again. also dont wait till it gets cold to run a heat pump. turning it on and off as it gets cold is not correct. you should select a temp ,usually 71 for heat and set it and leave it on to do its thing.you may want to check the charge. hot gas discharge is usually 100 degreees hotter than outdoor temps after 15 minutes run time. for example if its 40 outside the big freon line outside thats insulated should be about 140 degrees. or you can run it 15 minutes and grab it with your hand . it should be almost uncomfortable to hold any length of time. careful some get quite hot. you also have the option of hooking up the electric strip to automatically come on if you push the stat up 2 degrees hotter than the temp in the room. that way you get heat pump and strips till temp gets within 2 degrees of set point and the strips shut off and pump maintains.good luck