Over the summer I had a company install a 95% efficient furnace (Goodman brand) and this unit runs like for 20 minutes all the time even after reaching the desire room temperature. My previous furnace would turn off as soon as it reach the desire temperature, just wondering if this how efficient furnace work? For example if I set the temp to 72, after it finishes running the thermostat says 74 or 75, I have compared with another thermometer and they both show the same temp. I guess for the temperature reaching so high it takes a while to turn back on, last time I jotted the time and it took 4 hours to turn back on.
Sounds like it is a stat issue. What kind of stat are you using ? Older mercury stats have a heat antisipator adjustment. Best to replace if this is the case.
They should have installed a new stat with the furnace, and set the cycles per hour in the configuration setup to prevent this from occuring.
This sounds like it could be a SWING or cycles per hour setting type thermostat; they usually don't run the temp that much above the setting though.
Four hours is a long time between cycles, unless this is during the day with a lot of solar heat.
What outdoor temps are we talking about, with perhaps little or no wind; where are you located?
Does it cycle on at the TH setting, say 72F?
I am located in Chicago, this winter has been a record mild, there is wind almost everyday. I did a quick look up of the current thermostat and it probably the most cheapest out there, it's a Robertshaw rs2110. The tech said it was good enough to work and that it linked to the electronic filter.
Originally Posted by udarrell
Is the new furnace variable speed? This along with the t-stat could be your issue. It might not be set up properly to work with your t-stat? What does your installer say about the new furnace running like that?
It sounds like the furnace is over heating the area before shutting down. The t-stat could be the issue or how the furnace is set up at the board? What size furnace did you have before compaired to your new furnace? In other words Btu rating?
The differential on that t-stat is factory set to cycle at 2° above and 2° below setpoint. A 4 degree swing IOW. It is adjustable. Get out the manual and set the differential for 1°.
Originally Posted by Caferacer
This is right out of the User Guide (that should have been left with you):
Press and hold BOTH up and down keys for three
seconds. DIFF will be displayed on the LCD.
• Press up to raise the DIFF to 3. This
setting INCREASES the time between
cycles by allowing your system to run
• Press down to lower the DIFF to 1. This
setting DECREASES the time between
cycles by causing your system to run
The DIFF settings remain the same for both HEAT and
COOL, and can be changed in any System Switch position.
When batteries are installed in the thermostat, the DIFF is
reset back to setting 2.
I'd ge a better thermostat. I had a Hunter thermostat like that. I hated it. No excuse other than in very mild weather to have a room swing more than +/- 1F. I switched to a off the shelf honeywell and it made a big improvement sicen it used preset CPH settings rather than just temprature only.
Chicago is record mild? Huh, last winter was defnitely very mild, but this winter, I think we're pretty close to an average winter down here, maybe just a little above average but light on snowfall.