We have a Lennox HP, 10 hpb42-5P (or SP) type of HP. We are using a WR digital Thermostat, when the temp is set on cool and a temp lower than the current room temp the system comes on and works, and come back on and continue to cool. However when the temp is in the heat mode, and the temp is set on the digital themostat above the current room temp the system comes on and runs warm air from approx ten (10 min) and stops and will not come back on until the themostat is set to off for a few minutes and turned back on to heat. It will then run for approx 10 min and will not come back on regardless as to how low the internal temp is.
What could be the problem??? Thanks in advanced for any help you may offer.

 

When it shuts down go to the airhandler and remove the front cover. There should be a flashing code.

Probably a dirty air filter or dirty indoor coil and shutting it down on high head pressure.

 

BiggRedd_1,

If I'm not mistaken, HP10 is about 20-25 yrs old, and is probably ready to be replaced, how old is the HP, t-stat and the indoor unit? Do yoou have duel fuel or electric backup heat? Does your system behave the same way in aux. or e-heat? Let us know

 

I have gas/emergency backup heating, when I move the themostat to emergency heat mode it does not come on, it makes a sound as if trying to switch over but nothing happens.

Mattison mentioned it may be a dirty indoor coil? Where would that be located?

Filter changed on regular schedule.

 

Read the next post. I had a computer glitch in my brain.

 

The indoor coil should be in the return air after your filter. Unless it's been replaced in the last 10 yrs, should look like an A. You don't have a circuit board, probably duel fuel kit mounted on the side of the furnace.

When was the t-stat (thermostat) installed? Did you replace it yourself? Old Lennox wiring are labeled entirely different than most of your newer thermostats. How old is the gas furnace, what make and model is it? Also, did the e-heat work last year?

If it's an original Lennox duel fuel kit call a professional. I wold have a very difficult time helping you chase wiring online. You could have a bad relay or loose wiring in the duel fuel kit. I might be able to help depending on the answers to the questions above.

I was caught up with the e-heat not working, what mattison said about dirt on the indoor coil is true it is a possibility and depending on age of furnace will determine whether you have a circuit board.

I will be leaving for work soon, will check for yor post this evening.

 

That indoor coil should be on top of the furnace. Not in the cold air return. Like Matt said check it for sureto see if its clean . You do change the filter every 30 to 90 days ,dont you?

when I move the themostat to emergency heat mode it does not come on, it makes a sound as if trying to switch over but nothing

Do you have a OT tstat that makes the switch over?

 

If I am understanding you correctly OT outside thermostat.

There is a FuelMaster21 with a circuit board inside next to the furnace, because there is a jumper on the circuit board (remove the jumper if using outside Thermostat).

I have run the system with and without the jumper, it still operates the same.

Thanks.

 

There is a circuit board at the Heat Pump, I do not know if this is also the outside thermostat???

Also inside the Heat Pump there is a knob with numbers from 0 through 50, What should this knob be set on (32) or some other number????


Help