OK, so i am doing my first 2-way system and I told the client that we can do HVAC now. I ran a CAT5e to each of the T-stats at pre-wire, now i need to get this working because he wants it.

What do I need? Aprilaire 8870 and the 8811? How does this connect to the HVAC unit?

I think the HVAC guys are going to hate me.

It's not too hard. You need an 8870 per hvac zone(however many tstats hvac guy wired for), an 8811 protocol adaptor and if more than 1 stat, the 8818 distribution panel. The 8870 will wire like any other unit as far as the hvac contractor is concerned. It also has some com terminals that you need to hook your cat5 to and on the other end it will connect to the 8818 and then to the 8811. Basically the tstat is the bridge between the furnace and your XP8 or any other control processor.

We always give the tstats to the hvac guy and tell him to install them without the cat5 so they can get their system fully functional to prevent the blame game of who is at fault when something doesn't work. Then once they are done, we connect the cat5 and take it from there.

If this helps, here is some reading for you [Link: aprilairecontractor.com]

I have 2 T-stats that I am going to control (Living area & Master suite)

I see a part# 8890 called "2 thermostat starter kit" that includes (2) 8870, (1) 8811, (1) 8818, and (1) 8027 power supply.

Do I only need one 8811 protocol adapter?

You only need 1 8811.

Homelogic makes the 8811 or at least the software that runs it. Their integration note will give a good overview of what it takes.

[Link: homelogic.com]

Beat me to it.

I love HL's documentation.

Just my 2 cents but I got away from using cat5e for the thermostat and/or sensor runs - I always use the bell wire appropriate for the run. Generally with the AprilAire, I throw the 8870 T-Stats and 8818 Dist. Panel in the mechanical and use the Flush Mount Sensors (I think up to 4 per zone?) where the T-Stat's would normally go.

I have the HVAC guy wire the T-Stats "as you normally would (4wire, 5 wire, whatever)" from the Furnace's to the central location and "you will still connect the T-Stats as you normally would" and we run the sensor wiring (2 wire bell) and handle the control wiring. They do what they usually do, just in a different location and they don't supply the Stats.

Be forewarned - - check all the wiring they install and where they pull it as getting some HVAC guys to do as you ask is like pulling teeth. Same goes if you are not doing the electrical and have to deal with electricians on lighting control. Can't wait for the day we involve plumbers for digital flushing control...

Thanks for the info guys.

What about an outside temp sensor? I see the price is pretty cheap for this cool add-on, but is it a PITA or does it require more equipment too?

Benford - how did you make out with this?

I just came across a client who would like to integrate his RTI t4 with HVAC now..

He already has a HVAC unit, do these 8870's work with almost any HVAC system?

Installed one in our home. Have really gotten to like it. I pull the outdoor temp in from the weather driver...makes for a very nice screen on the T4.

How is the programmability of the thermostat? I read somewhere that the Aprilair piece can't be programmed to turn on to a specific temp at a specific time... you know, like a normal programmable thermostat. I've also heard that they could be programmed that way via the two way drivers.

*it should be known that I haven't downloaded the drivers and played with them yet.

I have finished the HVAC integration portion of this system and it works great. No the 8870 is not a "programmable" T-Stat but I plan to offer my client an upgrade at an additional cost that would consist of me programming a few different macros on the XP-8 that would execute HVAC commands at pre-determined times.