What's wrong with this thermostat?
It's a fine thermostat, a brand universally used for replacement thermostats.
It's new and programmable!
It's in a good place in the house!
It's a little off kilter on the wall, but that doesn't matter.
It's okay in every regard ... except one.
Why is it wrong?
This is a newly-renovated house.
It has a new roof (second layer), new drywall in the basement (replacing drywall damaged by a previous and maybe ongoing foundation leak), new appliances, new carpet, new paint, new deck (with a trip hazard and stairs not to code), and new HVAC system!
The new HVAC system was even installed by a professional company, well known in the area with lots of TV commercials.
Before the buyers arrived I did a complete recon of the outside of the house. I am habitually early, so when the buyers arrive I can begin to speak about the house.
I look to see what the house has in terms of systems. There was a gas meter and
there was a brand-new air conditioning compressor out back.
Key word: air conditioning.
In previous emails I learned that there was a new roof and HVAC system. So I examined the compressor. It was fine and installed well.
But when I got inside I saw this thermostat. I said out loud, "Why is there a heat pump thermostat here with a gas furnace?" Going back outside to examine the manufacturer's plaque in detail (with my glasses) I discovered that the compressor was not a heat pump compressor!
My client's brother was present, and is an HVAC guy. He went outside and confirmed my statement.
How can you tell it is a heat pump thermostat? There is an extra place for the system button to be set on. Here it says "Em. Heat." That controls the electric resistance portion of the furnace in a heat pump system, and is used if the heat pump compressor breaks. It gives you heat while you are waiting to get the heat pump serviced.
The professional HVAC company installed a new system (cheap builder grade, not their style - they usually get people for the most expensive stuff) but with the wrong thermostat.
A heat pump thermostat has 7 wires coming from the wall to connect to the thermostat. A combo gas/AC system thermostat only has 5 wires. So this guy went to install the thermostat, saw the two extra wire screw locations on the back side of the unit (perhaps not having read the box which said it was for a heat pump), and
1. Realized it was wrong but installed it anyway, or
2. Brought the wrong thermostat with him, didn't have the right one and wanted to get done, and, thinking nobody would notice, installed it anyway, or3. Didn't know it was incorrect.
My recommendation: on home inspections I check to see if the thermostat is compatible with the system it services. Replacement thermostats are cheap (yes, I know, there are some real expensive ones). They are easy to install. I installed a new programmable thermostat in my house many years ago. Just follow the instructions. A professional company should know the difference between a gas/AC thermostat and a heat pump thermostat. Let's hope so anyway...
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560