Thermostat Question


Active Member
Hi, all. I'm setting up a new Elk M1G system. For many years, I've used a Honeywell Chronotherm III setback thermostat to control our forced air natural gas fired furnace and our AC. The thermostat has been highly reliable and easy to program. When we go out it is quite easy to reduce the temperature and put it on "Hold" to save energy.

Now that I've got the Elk, I'd like to install a communicating thermostat connected to the Elk to automate energy savings when we go out or away. My needs are simple:
  1. When I arm the Elk, but the thermostat into "Away" or "Vacation" mode and hold it in that mode until the Elk is disarmed.
  2. Thermostat should be completely operable locally (at the tstat) for make tweaks to the temps if we are too hot or too cold.
  3. Returning from vacation or a trip, be able to phone the Elk and have it tell the tstat to go off Away or Vacation mode and revert to full automatic setback control
I've read everything I can find about RCS, HAI Omnistat, and AprilAire and it appears that none of these three offer the simple features of #1 and #2 above. Worse, it seems that if you choose to control the tstat from the Elk, you lose all local control at the tstat itself. Conversely, if you want to use the built-in setback features, you lose the communicating ability to the control system.

These seem like such obvious and desirable features that I'm shocked that they aren't included. On one site, a person contacted one of the manufacturers and was told there was no demand for these features.

I've seen several suggestions where people essentially use the event capability with time and temperature readings to set up rules in the Elk. These essentially completely replace the setback programming already built into the tstat. That seems like a real Rube Goldberg approach to what should be simple -- have Elk tell the programmable tstat to go into Away or Return mode.

Question: Do any of the communicating thermostats out there offer these simple features? Maybe things have improved in the past few years since the various reader comments were last made. I cannot find an answer to these simple questions on the RCS, HAI or AprilAire installer or user instructions.

Thanks in advance!


Active Member
I have an rcs that I'm controlling with 3rd party software (cqc) and it does all those things. I'll be integrating it with elk in the next few months.


Senior Member
Yes, you put the rules in the Elk and don't use the thermostats scheduling. The Elk is a lot more flexible than the thermostats programming, and I think a lot of people prefer it that way. You can write your rules to depend on custom values to make them easier to change if you want. I.e. if you want it to go to 65 when away,you can make the 65 a custom value in the elk so it can be changed, or you can make the setback dates/times custom values. I too use CQC to manage my custom values in the Elk. The elk also updates its clock, etc, so no more having to deal with daylight saving on your thermostat (assuming your daylight savings time is workign correctly on your Elk :)

For example, one of my favorite rules is on weekends to not turn the heat on until motion is detected in the house. When the heat kicks on, it tends to wake me up. On the weekdays that's fine to get me up for work, but when I want to sleep in on the weekends it doesn't wake me up anymore.

Initially you may find yourself wanting to tweak settings, but I haven't touched my custom values in over a year. Usually what I did was walk over to the thermostat and reset the temp to something and if I found myself doing it too often I changed the value permanently.


Senior Member
I too just have my setbacks contained in the Elk - and not even gracefully; the rules are in Elk and have to be updated in RP - no custom values (which would be smarter)... but since I never seem to need to change it, it's been fine for the most part.

That said - with my RCS thermostats, that's absolutely doable - and pretty easy. You can set all your different home/away/vacation settings in the thermostat, and then have rules in your elk that send special text strings. You'll make up a text string for each of the modes, then when you want to activate a particular mode, you just send the text string over the XSP's com port to trigger the change. The Elk will still set the time, and you'll be able to override temperates at will via the Elk, but the programming will continue via the tstat itself... kind of a best-of-both-worlds scenario. Granted, it's not as clean as a rule that says "Set mode Vacation" - but once you set up the strings, they're there forever.

I use text strings to also display the outside temperature on my thermostats (obtained via by Elve and stuffed into a Custom Value, which the Elk then sends to the thermostat)... and also to trigger a flashing red light when I'm running the A/C but should just open windows and use the whole house fan.