So I replaced my old goodman that had a cracked heat exchanger with a brand new Payne 92% efficient furnace. First issue is a "bong" noise that happens when the inducer motor starts. It sounds like you're hitting a bong when the inducer motor starts. It has a condensate pump attached and thats how it voids water. Any ideas what that could be? Secondly and most importantly I have a new Honeywell thermostat with the touchscreen and color screens. I have the set point at 75 and the thermo reads only 66..67..68..69 max. What can possibly be wrong with this thing. I am getting beyond frustrated now. Thanks.

It's a PG92S down flow natural gas
Thermostat is a honey well rth9580wf1005

 

Does the actual room temperature keep rising above 69° until it reaches 75° ?

 

That's room temperature and what the stat reads.

 

Then you're saying the room gets to 69° and the furnace shuts off.

That sounds like a thermostat problem.

 

How do I tell if the thermostat is bad?

 

Testing again. Thermometer is at 68. Thermostat states 69. Set point is 71. Never reaches 71 during cycle.

 

Quick question. Is there a relationship between flue size and heat output? For example, is going from a 2 in flue to 3 in get you better unit performance?

 

Do not try to "second guess" the manufacturer. The manufacturer will state in the installation manual the proper size pipe to use for air intake and venting purposes and whether or not the size needs to be increased if the run is over a certain number of feet. This has to do with proper combustion and almost nothing to do with the actual heat output.

It IS possible that the thermometers, both the independent one and the one in the thermostat, are out of calibration as well as the thermostat switching also being out of calibration. Unfortunately there is not a lot of accuracy in any of these products unless you spend a tidy sum of money and even then no guarantee of accuracy. Instead of absolute accuracy what you want is repeatability. That means if you set the thermostat at 71 and it repeatedly maintains the temperature at 69. In this case merely bump the thermostat up or down to a setting where you feel comfortable, regardless of the displayed temperature.

 

ES,
A couple of questions. I see that Payne PG92S actually is the model number for 4 different sizes from 60,000-120,000 btu's. What is the size of your furnace.
The next question. When you set your tstat @75° and it only reaches 69° does the furnace keep running to try to reach the set temp which would mean the tstat is still calling but the furnace may not be large enough to do the job.
If the furnace actually shuts off at 69° while set at 75° you most likely have a tstat problem.
Strickly heat you probably just have a 2 wire tstat.
What you can try is remove the tstat off the wall if you're comfortable doing that and twisting the 2 wires together. It is only 24V and no danger. The tstat is only a switch but with sort of a brain to know when to start & stop.
When you jump the wires the furnace will stat running until you separate them. If your furnace reaches the temp. in that way you may want to change the tstat. If the furnace never reaches temp. it probably either isn't big enough or you're not getting enough air flow into the space.
Good Luck,