This seems like the best place to find some advice before I call in our friend that does HVAC for a living.
In our old house, there was an electric furnace and heat pump. It had a normal thermostat that showed the temperature, had a few switches, etc. and was controlled with a slider on the top. It also had an emergency heat function, which I’d never had before, but I’d never really thought about.
In our new house, we have a gas furnace in the basement and a heat pump as well. We have an old thermostat that is a twist knob with clear front. It has likely been in the house for a long time, but the furnace and heat pump were added by the previous owner to replace the old system about 2 years ago.
With no emergency heat option, there is no way to tell our furnace not to use the heat pump, even though it is about -3 overnight here right now. It seems that the heat pump can’t keep up, which would be a good time to change to emergency heat, had there been a setting for it.
Shouldn’t there be some sort of option for this? Should I have someone come in and replace the thermostat? Or is this a larger issue?
I’m a retired HVAC guy who only worked on commercial equipment. Virtually no experience with heat pump systems.
However, my guess is you should have a thermostat put in that incorporates everything you had on your old system.
For the present, can you just switch off the heat pump (at the disconnect if necessary) and let the thermostat run the furnace?
Edit: After rereading your post, are you saying that at -3 the furnace does not come on at all? If that is the case, then yes, the thermostat likely is the wrong one for your system.
While my heat pump does have a switch to start the emergency heat, which comes on periodically to defrost the heat exchanger coils even in relatively mild temperatures, if the set temperature is more than 2 degree F higher than the inside temperature will come on automatically. Yours should have a similar feature if the thermostat is set up properly, but the previous owner may have added the gas furnace and the heat pump separately without the proper interface. I’d call my HVAC buddy for advice.
Newer thermostats can be programmed to kick in emergency heat (your furnace) when the exterior temperature reaches a particular trigger point. I think ours is 37F or some such. Heat pumps don’t work efficiently in very cold weather. I’d suggest that the OP have someone come out and install one for him.
You’ve not got the right kind of thermostat. My heat pump is geothermal, but I’ve had an air to air unit in the past.
In normal operation, say at 40°, the heat pump runs and supplies all the heat required. If temp drops so the pump can’t keep up the electric coils come on in stages to maintain set temperature.
Once outside temp drops to a certain point the pump shuts down and the electric coils supply all the heat. This temp can be set by your HVAC guy.
Note that the heat pump will never fall below a one to one ratio of supplying heat, but many folks feel that below a certain point they’d rather save wear & tear on their equipment.
I mention electric coils taking over, but a gas or oil furnace works too.
Gas is often significantly cheaper than electricity though, so it could well be worth turning on the gas furnace at a relatively moderate temperature. When the emergency heating is electric, yeah the only savings you get is the wear on the heat pump.
I don’t know anyone with such a system, but I’ve heard that some installations incorporate multi fuel backups and the user can choose between for example gas or electric backup. Seems like it might be an expensive install.
When the heat pump can’t keep up does the gas furnace fire up at all.
Here is my swag. When the heat pump was added the old stat wire was probably used, and it does not have enough wires in it to wire up heat pump with gas emergency heat properly. So you may need to pull a new control wire from stat to furnace. Or the wrong stat was installed.
The original setup when I bought my house was heat pump w/ gas backup. When I bought a programmable thermostat, of about 20 models in the Orange hardware store, there was only one I could buy because of the heat pump & emergency backup; it was, of course, the most expensive model & had some ridiculous amount of wires (9 or 12 as I recall).
Seems like you might not have the correct thermostat.
BTW, at the direction of my HVAC guy, I always used Emergency heat/gas & used the Heat/heat pump as my emergency backup as this climate is too cold for a heat pump in the dead of winter. He said this would be more efficient & less expensive.
I think this is exactly it - the old wire must have been used. The heat pump is on it’s own breaker though, so when I got home I turned the system off at the thermostat and went out to turn off the breaker. Came back in and turned the thermostat back to on and set it at a normal level (67ish) - I went over into our unfinished/unheated addition to hang some drywall and came back over in an hour. The house was considerably warmer and this seems like it solved the problem.
We have a gas backup, but it never has gone to backup because it doesn’t have the option to switch to it and we never considered it. Last year, in the super cold (I remember leaving for work in about -10 to -20 temps some times) was our first winter in the house, and the entire furnace didn’t work because of a faulty ignitor and some other various problems (I suppose - I replaced the ignitor the next day and our HVAC friend did a few other things downstairs). Pretty soon we will have to get him to come back and check out the thermostat.
I was at Costco this afternoon and saw a First Alert brand WiFi thermostat. It said on the package that it was usable with heatpumps. You can control it with your smart phone. $199 US.