OK ... I know this has been discussed before, but ...

I have an Elk, and now I am ready to buy a thermostat. I have only 1 zone so I only need one tstat.

I understand that these are my choices:

AprilAire 8870 + 8811 + 8818 (needs protocol adapter and control unit)

Right now I am leaning toward RCS TR16, mainly because:

1. I actually like the minimalist styling.
2. The other messages that can be displayed on the TR40 can just as easily be displayed on elk keypads. What other advantages does the TR40 bring?
3. AprilAire gets expensive once you buy the additional parts.

I haven't researched the HAI option in great detail. Any advantage to these?

Any opinions?

Another questions ... I know I don't need multizones, but what exactly is a two-stage tstat, as in:

in a heat pump system, the two stages of heat are 1) running the compressor, 2) running the electric heat strips. I believe that for two stage air conditioning it means that you have variable output compressor and/or blower. If you have a multi stage system, then you need a multi stage thermostat. If you have a single stage system, then buying a two stage thermostat is overkill.
With respect to the RCS TR16 or TR40....

The WDU (wall display unit) is the only difference between the TR16 and TR40 units. You DO WANT the larger display (TR40) for a couple of reasons.

The larger display will allow you to set and enter schedules and adjust many of the variable parameters within the Tstat (it is quite flexible). If you do not get the larger WDU, you would have to connect up the PC to the Tstat to make all your adjustments - entering them through the 16's display unit is not possible.

To connect up to an RCS Tstst with a computer, you will need an rs485 to rs232 converter that will then connect to the computers serial port. RCS supplies software with the Tstat that will let you change all of its settings (configure it). Not having to use the computer to set-up the Tstat is the advantage of the larger WDU.

As for displaying messages on the Elk that could be displayed on the RCS TR40........can't really comment on that yet....still playing around.
If I connect the TR16 to the ELK (which I plan to do regardless of which tstat I get), can I program it that way?

Any pros/cons on the HAI tstats?
Short answer is ....mostly yes.

The Elk will allow you to set heat/cool, turn the fan on/off etc. Look in the Elk RP software ...in the rules section .....under Tstats to see all your options. You have a good amount of flexability there (probably all you will need).

What the TR40 will let you get to that the Elk won't is the internal schedules that the TR40 can run (probably not needed if you are going to use the Elk anyway). But there are some other system parameters such as "minimum system run time, time off between runs, and other basic level HVAC set-up stuff that can only be accessed by the TR40 or the software interface.

Hope that helps.
3DogKnight said:
AprilAire 8870 + 8811 + 8818 (needs protocol adapter and control unit)
I don't believe it's correct that the AprilAire 8870 communicating thermostats require the mentioned 8811 and 8818 products.

The 8870 thermostat, as an HVAC controller, functions as any standard thermostat does. I.e., you can just hook it up to your HVAC equipment as you would any thermostat and it will properfly perform.

The communications side of the 8870 is simply a standard 4-wire 485 serial communications port. ANY 485 serial communications port will connect up to the 8870 just fine.

For example, HomeVision (automation system), like others, offers an optional 485 serial communications adapter. While it isn't the prefered way to hook up 8870s to HomeVision, technically it works just fine.

AprilAire's 8811 is simply an RS485-to-232 serial converter - any similar product will work fine. If you want to hook up your computer directly to the 8870s, then you'll need this 485-to-232 serial converter.

The 8818 distribution is nice if you have a number of 8870s. I've got six 8870s, and thus the distribution panel helps a lot. But you can easily do the same with a Cat5 or Cat3 punch panel.

Hope this helps.

Best regards,

Bill Neukranz
The communications side of the 8870 is simply a standard 4-wire 485 serial communications port. ANY 485 serial communications port will connect up to the 8870 just fine.

Yes, but, thermostats connect to the ELK via 232, not 485. You need the protocol adapter with Aprilaire.
3DogKnight said:
Any pros/cons on the HAI tstats?
Don't know if you've decided yet, but I've got the HAI stats. I originally wired them up and programmed them manually. Later I updated code in MisterHouse to give me a web interface for the basic functions.

The pros are:
1. Easy to install.
2. Can be programed independently of an automation system
3. Not too expensive.
4. Serial addressable so you can connect more than one to a single serial port.

The only con I've found is that they are not as widely supported as some of the other vendors.
The Aprilaires seem nice, and from an automation standpoint they are pretty well done. Proliphix is another option. They have IP based thermos as well.
3DogKnight said:
If I connect the TR16 to the ELK (which I plan to do regardless of which tstat I get), can I program it that way?

Any pros/cons on the HAI tstats?
I just noticed this. Not sure if you made a decision yet.

I have a HAI thermostat I've been using for awhile. I purchased it when I was expecting to buy a HAI system. I later decided on an elk.

I have mine connected to the elk and it was working well. You need to send the HEAT command before changing the temp as it seemed to not work reliable using elk rules at first, but I believe that resolved the issue.

As far as pro's/cons, a few things to be aware of:

1. I believe they should fix the mounting a bit. The face snaps into the piece mounted on the wall, and a better mechanism for doing this would be my recommendation to HAI. I had to play with mine a bit so it was clean (it did not seem to sit as cleanly as I would have expected). Note, I only have one, and it could be mine was 'bad' by the time I got around to putting it in I did not pursue seeing if it was my unit or the design in general.
2. You really want it at eye level, if it is off a bit, certain angles will let you see the outline of the characters that can be displayed on the screen.

The blue backlight is nice, and the unit was pretty inexpensive compared to some options.

Overall I can't complain much about them. If I were to do it over however I would probably look at Aprilaire and the other one even though they cost more. The messaging aspect is kind of nice. There was a substantial difference in price if I remember correctly. I have an older house, so it is one zone heat (and it was apparently pretty complicated to change that) and one zone cooling (or will be), so I don't have the best 'testbed' for stats.