Hello,
My decrepit gas furnace is being replaced by a new Trane heat pump with a single speed 95% gas furnace. I have the Iris/Radio Thermostat CT101. I’ve excluded the thermostat ahead of reprogramming it and re-including it.
So any one have any tips or gotchas I should be aware of? Any plug ins that optimize dual-fuel furnaces? PLEG or LUUP code that may make my life easier?
I expect the heat pump to handle things 9-10 months out of the year but ~2 months we get temps down below 20F/-5C and the gas will be the real heat source.
Oh and one of the reasons I have not gone with UI7 is that we have days with 40+F temp swings in spring/fall. I can need heat at 3am and AC at 4pm. I can tolerate a fairly wide temperature range and just showing the active mode temp doesn’t cut it for me.
Note to others: the ct101 supports 2 stage primary and 2 stage secondary heat but the secondary heat is inaccessible over zwave. It either activates automatically or manually from the thermostat. I tried sending every optional command to control the emegency heat, aux heat and secondary settings with no impact.
So, yeah, that sucks a little.
What model heat pump do you have? I have an xl20i that is two stage. The compressor outside has two stages, a smaller and larger compressor. The system switches between the two automatically depending on demand. My backup is propane. That is usually called emergency or aux heat.
@kigmatzomat
Most thermostats/heat pump systems are optimized for efficient use.
With a two stage heat pump … you will have 3 stages of heat and two stages of cooling.
The heat pump stages (H1 and H2) will only operate in the winter when the temperatures are adequate for operation.
The number of stages (H1, H2, H3) is dependent on the temperature difference between the setpoint and the room temperature.
When it is two cold outside for the heat pump to run … then H3 will typically be engaged when normally only H1 would be called for.
This is an automatic switch over for Aux Heat. Some cheaper units require you to manually set the thermostat into AUX heat mode when it’s cold outside
so that H3 is called by the thermostat and H1 and H2 are never engaged.
I am pretty sure the Trane xl20i will do the auto switch over … I have the next lower efficiency line … and it does.
The furnace does switchover between primary and secondary heat automatically based on temp.
What I’d hoped to do is use the Vera to kick the heating system into aux/emergency mode to only use gas when the power is out. Between ice storms and wind storms, I lose power at least twice a year for a couple of hours. There are also numerous micro-outages where I lose power for 2-3 seconds.
So I’m looking at adding a solar array with batteries to my house. Not a huge system, just enough to lower the peak power loads and, if the power’s out, give me a few hours for critical circuits without breaking out my portable generator. Heat pumps would eat that in a few minutes and I’d like to be able to use the Vera to manage that mode change automatically, or allow me to do it remotely.