I inspected a 2005 two story home with finished basement with total square footage of 3,751. The home had two Rheem 80% efficient, 75,000 BTU each, model number RGPN-07EAMER for both, furnaces with one Honeywell thermostat on the wall of the main level. Can anyone tell me why two furnaces were installed with one thermostat? It seemed odd to me that only one furnace with a higher BTU was not installed.
Did it have a 2 stage heating thermostat?
I believe it is a 1 stage, multi-speed/position upflow with 1200 cfm furnace
if they both come on at same time and run on 1 stat they have been twinned together are they right next to each other do they have seperate duct systems?
they are next to each other in the basement and do have separate duct systems?
Exactly ,they have different zones they cover.
Really curious on why they would not install only one furnace since on only one thermostat since all zones are conditioned at the same time.
maybe 1 stat on lower level also?. 1 furnace for upper level 1 for lower level.
Must say I have never seen two furnaces on one thermostat not to say it could not be done I just have never seen one wired that way. I would have looked real hard for that second thermostat.
It would be interesting to know if both furnaces had one low voltage transformer or two and if there was only one transformer what its size was. A normal furnace split system with A/C unit takes at least a 40 va transformer to operate the low voltage controls and if both furnaces and A/C units were operating off one low voltage transformer it would have to be at least 70 va just saying;-)
I commonly find the second thermostat neatly hidden behind a bedroom, office, or den door
I’ve seen it before, but very rare and it was coupled with Big-*** commercial A/C system.
Did the two systems share an A/C condenser or did they have separate? If there were separate condensers/coils, I’d bet there was a separate thermostat.
I too have primarily seen this in commercial applications, but I have seen this once in a large old cotton plantation house.
I also suspect incomplete information as to the equipment on-site.
Seeing as home inspectors do not have sufficient background to inspect HVAC equipment in many cases, reverting back to the standards of practice; did you turn on the thermostat and both units responded?
This would clear up a lot of things…
If not, I sure wouldn’t be calling in an HVAC contractor on this one (Except to do the inspection 4U).
I would probably go back and finish the job before I wrote the report also.