Thermostat recommendations?

I am completely new to the world of home automation. However, my thermostat needs to be replaced, and I would very much like to replace it with something that I can program from my PC. Having said that, I don't really know where to begin. Has anyone got any suggestions for me?

Here is a further elaboration of my situation. I would like, eventually, to put controllable dampers or flow controls or whatever they're called into the pipes from my furnace/AC so that I can control different zones separately. However, I can't afford that right now. So, I want to start by replacing my thermostat, with a view to building the system out further if/when I can afford more.

I have done a little reading on the net but it hasn't gotten me a lot closer to a solution just yet. I've read a little about X10 and RS-485, but being new to this field, I generally get confused before I get very far. Can someone offer me guidance as to exactly which components I'll need to buy now in order to hook up a thermostat to my PC and be able to control it?

Thanks a lot! Brad.

Reply to
Bradley Plett
Loading thread data ...

There are some pages you might find of interest at....

formatting link
Hope it helps...

Tom

Re- thermostat: If you live in a place where pipes freeze:

Put a traditional t'stat in to maintain a minimum heat. Fit "computer controlled" "t'stat" in parallel with the safer one, and use it to boost the t'ture as suits your needs... but whatever happens, at least your house gets enough heat to keep pipes unfrozen...

Reply to
Sheepdog

I put one of these in myself a little over a year ago. I loked at quite a few models but finally went with an RC-122 thermostat from HAI. I have had no problems at all with it.

The features that made me decide on this one were:

- Serial port connection (this one can also do RS-485 I think)

- Compatible with their Omni series home automation controllers (I want to get one when I can afford it).

- Can display outside temperature (either with external sensor or update from the computer).

Their protocol isn't that difficult, and if you are connecting it to a PC they have a program you can use so you don't have to write any code.

I bought it from Worthington Distribution

formatting link
prices are good and their service is excellent.

BTW, unless you have a two stage furnace, you don't need this model-- it's about $40 more for the two stage if I remember correctly.

I hope this helps.

Bill

Bradley Plett wrote:

Reply to
mcbill20

Brad, I will try to answer your questions:

  1. You can connect it to your PC's serial port. It only uses pins 2, 3 and 7. If you are out of ports you can get a USB to serial adapter and connect it to that. You may also be able to use RS-485 if you have a long distance to connect. I'm not totally sure on this part so I'd check with the manufacturer.

  1. I don't know for sure whether or not they have an API but I believe they have software that runs on a PC. I am controlling it from a VMS system so I had to write all the software myself. The programming is pretty straightforward.

  2. If you don't know what type of furnace you have, I would either check the thermostat type or get an HVAC person to check it for you. You could use a two stage thermostat on a single stage furnace but it would be a waste of money. And if you use a single stage thermostat on a two stage furnace you miss out on the cost savings of running a two stage furnace.

  1. This thermostat is not compatible with X-10. I had originally thought it could be used for either RS-232 or RS-485 but now I can't find any info on the RS-485.

I hope this helps.

Bill

Reply to
mcbill20

Brad, I will try to answer your questions:

  1. You can connect it to your PC's serial port. It only uses pins 2, 3 and 7. If you are out of ports you can get a USB to serial adapter and connect it to that. You may also be able to use RS-485 if you have a long distance to connect. I'm not totally sure on this part so I'd check with the manufacturer.

  1. I don't know for sure whether or not they have an API but I believe they have software that runs on a PC. I am controlling it from a VMS system so I had to write all the software myself. The programming is pretty straightforward.

  2. If you don't know what type of furnace you have, I would either check the thermostat type or get an HVAC person to check it for you. You could use a two stage thermostat on a single stage furnace but it would be a waste of money. And if you use a single stage thermostat on a two stage furnace you miss out on the cost savings of running a two stage furnace.

  1. This thermostat is not compatible with X-10. I had originally thought it could be used for either RS-232 or RS-485 but now I can't find any info on the RS-485.

I hope this helps.

Bill

Reply to
mcbill20

Thank-you VERY MUCH for your post! It really was a very helpful start.

So I immediately did some reading on the RC-122, and once again came up with more questions that are answered neither by the documentation I've found nor by your response (well, you imply answers, but.... :-)

  1. How do I connect it to my PC? All the stuff I found mentioned only connecting it to an Omni controller. Do I need any thing other than the thermostat in order to connect it to my PC? Does it plug right into an RS-232 or a USB port? (Actually, I think
    formatting link
    answers this, and that it simply plugs into the RS-232 port, but it's always nicer to have confirmation. :-)

  1. Assuming I can connect it directly to my PC, can I program it myself? Do they provide any software or API? I am a developer, and enjoy the programming aspect of this, but I'd still like to know that there is a starting point without having to buy more. (Again, I think the link answers that, but....)

  2. When it comes to furnaces and air conditioners, how would I even know if I need a one-stage or two? If I buy the two-stage thermostat, is it safe to assume that it will work even if my furnace or A/C are single stage?

  1. I assume that HAI's control system and protocol is not compatible with X10 nor RS-485, is that right? I don't know how important this is, but I do want to have an eye on the future when purchasing.

Thanks again! I feel like I've made a giant leap forward due to your post. :-)

Brad.

Reply to
Bradley Plett

Thank-you VERY MUCH for your post! It really was a very helpful start.

So I immediately did some reading on the RC-122, and once again came up with more questions that are answered neither by the documentation I've found nor by your response (well, you imply answers, but.... :-)

  1. How do I connect it to my PC? All the stuff I found mentioned only connecting it to an Omni controller. Do I need any thing other than the thermostat in order to connect it to my PC? Does it plug right into an RS-232 or a USB port? (Actually, I think
    formatting link
    answers this, and that it simply plugs into the RS-232 port, but it's always nicer to have confirmation. :-)

  1. Assuming I can connect it directly to my PC, can I program it myself? Do they provide any software or API? I am a developer, and enjoy the programming aspect of this, but I'd still like to know that there is a starting point without having to buy more. (Again, I think the link answers that, but....)

  2. When it comes to furnaces and air conditioners, how would I even know if I need a one-stage or two? If I buy the two-stage thermostat, is it safe to assume that it will work even if my furnace or A/C are single stage?

  1. I assume that HAI's control system and protocol is not compatible with X10 nor RS-485, is that right? I don't know how important this is, but I do want to have an eye on the future when purchasing.

Thanks again! I feel like I've made a giant leap forward due to your post. :-)

Brad.

Reply to
Bradley Plett

For easy single-point PC control, you can get an IP thermostat with a built-in web server like the Proliphix

formatting link
Instant PC access, but you have to run Cat5 to your thermostat location.

You could also get a direct-RS232 or RS-485 controlled unit. One example is the HAI RC Series

formatting link
Another example is the Aprilaire 8870
formatting link
get quite expensive if you want zone control, as you have to by the HAI Omni or an Aprilaire system controller to do this (and I think only certain Omnistats work with zoned systems).

But what might be a good fit for you is the RCS series

formatting link
It uses your existing thermostat wire to communicate from the thermostats to an included controller, so it's easy to retrofit. But it is easy and cost-effective to grow it into a full zoned system with automatic damper control. Be careful when buying from places like Smarthome--they only sell the thermostats in a bundle with a controller. I've seen people buy 6 sets from Smarthome, and then they have a stack of five extra unused controllers. Find a place where you can buy the Wall Display Units separately (i.e. Worthington, $75) and a separate zone controller ($150-300 depending on number of zones and communication options). Lots of home control software (including the free MisterHouse) can interface with an RCS system.

Hope this helps.

- Mark.

Reply to
Mark Thomas

HAI, does sell a pre-made cable for connecting the thermostat to a pc.

If i recall correctly they made a simple pc app to control the rc-series thermostats. If not they have published the protocols of their Omni Protocol. You could write this into a software app as needed.

Reply to
Brett Griffin

Well it really depends on what you are hooking up to the thermostat. If you are using an HAI Omni system the HAI tstat makes sense. April Air get the votes for looking the best, and I dont know much about RCS.

They all can connect to a PC.

The only other concern would be cost. I think the HAI RC-80 Single stage thermostat will be the cheapest of the bunch.

Reply to
Brett Griffin

OK, this post was very helpful! Now I'm wondering if I can get some pros and cons of the different options. For example, what are the pros/cons of the HAI vs. the Aprilaire vs. the RCS?

I'm not particularly interested in the one that has a web server built-in. Also, I would assume that even if the thermostat can't control different zones, if I ran everything from my PC that wouldn't be a problem, since I could program the different zones myself. Any more thoughts?

Thanks! Brad.

Reply to
Bradley Plett

In addition to the other issues, you also need to get power from the furnace to run the HAI thermostat. The power drain is very low and most furnaces can do it easily, but I believe that you need at least a three conductor cable from the furnace to the Tstat. If you have an old system with 2 wire cable it will not be adequate. You might be able to pull a new wire from the new Tstat to the furnace. Check the HAI site for installation info on these models for further info.

Reply to
George Pontis

WOW! Do you really mean DEC VMS?! I haven't worked with one of those for so long I was starting to think they were extinct!

I'd like to try programming my thermostat myself, but I can't seem to find any information on it. I see many places where it says "Protocol is available from HAI web site", but I can't seem to find it. :-(

Any code samples or protocol information you have would be much appreciated.

Thanks! Brad.

Reply to
Bradley Plett

Reply to
Bradley Plett

You must have access to the dealer site to get access to the protocol information. Contact your local HAI sales rep to get a username and password.

BTW, I will email you the protocol document.

Reply to
Brett Griffin

In the back of the RC-122 install manual will show you how to build a serial cable to connect to your pc.

Reply to
Brett Griffin

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.