HVAC and 2 stage furnace question
I had a new furnace installed about 2 years ago – moved from an 80% to a 95% 2 stage Trane. When the HVAC tech programmed the board of the furnace from when to kick from Stage 1 to Stage 2 – we had crap insulation in the house – this summer I tore it all out, air sealed, and installed new mineral wool R15 in the bays and R30 perpendicular. My house is A LOT more comfortable.
My question is with the furnace – it always kicked into stage 2 even when just up keeping temperature. This is because the time it took to get to the set temp on the thermostat. Now with the home being so much more insulated, it kicks into stage 2 for maybe 1min and then shuts down – seems like a waste of effort. Should I expect the furnace to maintain internal temperature in just Stage 1? If so I will ask the HVAC tech to re-program the board to run in Stage 1 for a little longer.
Any advice is helpful – thanks in advance
Replies
the first stage should be able to maintain the temps in all but the coldest weather. (if you have the system sized correctly. the design conditions should give you a system sized to heat to your comfort level on the coldest day of the year.
It is good to run the second stage once in a while, to make sure it works.
Do you have a two stage thermostat? They can be good since they provide a way to let the system know what you want.
the second stage can come in handy when you have reduced the temperature to save money, and want to warm up quicker.
Yes I do have a 2 stage thermostat. Its a Nest Gen 3 I believe but the color definitely changes when it kicks into stage 2. I just want to know if my system is sized properly. There is still a ton of insulation and air sealing to do on the walls of my house. I just am trying to find easy ways to tell if what I'm doing is working. I think it is - but the house (everything in it) is so drafty - the 2nd stage still kicks in after air sealing and insulating the attic with R45 (R15+R30)
The way to judge is to run the numbers on your utility bills usage, and compare vs degree days.
when i first had our two stage furnace in would also kick in the second stage after a set time. I had a zone system and was able to upgrade the control board and set it so the second stage of heat would not come on unless both zones needed heat.
not sure if you can modify the programming on your thermostat to extend the first zone time. it seems to be mostly automated beyond your control, but there might be some setting on an app you can play with.