The Great Thermostat Search

[beelzerob]

So, as part of my geothermal adventure, I have to secure a thermostat to handle the requirements. I currently have a RCS TR-15 that has worked good enough for my existing heat pump. But since I'm upgrading everything else, I might as well go fancy on the thermostat too.

I've looked over all of the contenders I know about, and there seems to be a dearth of viable choices. Here are some of the requirements:

• Heat Pump compatible
• Heating Stages (3)
• Cooling Stages (2)
• Humidifier Control
• Damper Control
• HA controllable (duh)

Now, I don't know if humidifier control is a reasonable expectation. Is there a thermostat that does all that? Is that something that is even reasonable to want to control through HA? I mean, isn't that pretty much a set and forget? Basically, I want to add a humidifer to the system, and I guess I want to know when the humidifier is "On". Not much else to know about it I think.... The one contractor so far has suggested the Aprilaire 400 Humidifier, and I think that comes with its own controller, which is *not* communicating I believe.

Then for damper control....I know that normally you would have a thermostat for every zone, and let them haggle and fight about when dampers open and close. However, I really don't want thermostats all over the place. I already have datanab temp sensors in all pertinent rooms. So I'd be just as happy controlling when the dampers move by myself. But I would need some interface for doing that, obviously. I know I can use relay control to power open and closed dampers....but I thought thermostats sometimes included that control too, and if they do, do they open up that control to a PC through a protocol?

I looked at the Aprilaire 8870, which seems to be the only one they have that is "communicating", but it didn't seem to have a wealth of features....at least, not the ones I was looking for. Is that pretty much the standard of what I can expect to find?

 

[Steve]

Have you looked at the HAI RC-2000? It's one of the most capable HA stats out. It seems as if it meets all of your criteria except perhaps damper control and I'm not sure you will find that in just a stat itself. I have the baby brother RC-1000 and really like it.

 

[fcwilt]

Damper control is usually handled by the zone controller.

In my home the actual thermostats needed by the zone controller are simple single stage heat/cool with auto-change-over.

After reading through the manual on the zone controller and all the things it does I decided to leave that task to controller and not try to get my home automation system to do it. The HA system does talk to the thermostats, RCS TRS-40s.

 

[beelzerob]

Have you looked at the HAI RC-2000? It's one of the most capable HA stats out. It seems as if it meets all of your criteria except perhaps damper control and I'm not sure you will find that in just a stat itself. I have the baby brother RC-1000 and really like it.

Good lead, Steve. I'll have to be sure that the Aprilaire 400 works with it for humidifying, but that's a good start. Does the 1000 do pretty much the same stuff, or is the RC2000 twice as good?

Next issue would be to see if I can get the comm protocol for the RC2000. How do you control your RC1000 with CQC, Steve? Through the Elk?

I guess the next question then is...how do people control their zones if not through the thermostat?

 

[jkish]

So, as part of my geothermal adventure, I have to secure a thermostat to handle the requirements. I currently have a RCS TR-15 that has worked good enough for my existing heat pump. But since I'm upgrading everything else, I might as well go fancy on the thermostat too.

I've looked over all of the contenders I know about, and there seems to be a dearth of viable choices. Here are some of the requirements:

• Heat Pump compatible
• Heating Stages (3)
• Cooling Stages (2)
• Humidifier Control
• Damper Control
• HA controllable (duh)

Now, I don't know if humidifier control is a reasonable expectation. Is there a thermostat that does all that? Is that something that is even reasonable to want to control through HA? I mean, isn't that pretty much a set and forget? Basically, I want to add a humidifer to the system, and I guess I want to know when the humidifier is "On". Not much else to know about it I think.... The one contractor so far has suggested the Aprilaire 400 Humidifier, and I think that comes with its own controller, which is *not* communicating I believe.

Then for damper control....I know that normally you would have a thermostat for every zone, and let them haggle and fight about when dampers open and close. However, I really don't want thermostats all over the place. I already have datanab temp sensors in all pertinent rooms. So I'd be just as happy controlling when the dampers move by myself. But I would need some interface for doing that, obviously. I know I can use relay control to power open and closed dampers....but I thought thermostats sometimes included that control too, and if they do, do they open up that control to a PC through a protocol?

I looked at the Aprilaire 8870, which seems to be the only one they have that is "communicating", but it didn't seem to have a wealth of features....at least, not the ones I was looking for. Is that pretty much the standard of what I can expect to find?

Check out the Honeywell IAQ 9421 series. It can do 4 heat stages and 2 cooling stages, humidification, dehumidification, zoning control (it can interface to the zone controller), and there is a serial interface kit for it too. I believe that someone on the CQC boards had mentioned that they had the start of a driver working a while back, but I don't know how complete it is. For dual fuel support, it has a droop mode where it will switch off of the HP when the system cannot maintain the setpoint.

 

[beelzerob]

Check out the Honeywell IAQ 9421 series. It can do 4 heat stages and 2 cooling stages, humidification, dehumidification, zoning control (it can interface to the zone controller), and there is a serial interface kit for it too. I believe that someone on the CQC boards had mentioned that they had the start of a driver working a while back, but I don't know how complete it is. For dual fuel support, it has a droop mode where it will switch off of the HP when the system cannot maintain the setpoint.

Excellent, thanks! I didn't know honeywell made a controllable thermostat. That's handy, since every HVAC contractor I talked to used honeywell thermostats...so maybe I won't have to get this thing on my own, I can just tell them which one I want (unless they play the markup game).

 

[Steve]

Good lead, Steve. I'll have to be sure that the Aprilaire 400 works with it for humidifying, but that's a good start. Does the 1000 do pretty much the same stuff, or is the RC2000 twice as good?

Next issue would be to see if I can get the comm protocol for the RC2000. How do you control your RC1000 with CQC, Steve? Through the Elk?

1000 is very similar, mainly doesn't do humidity.

It's actually not being controlled just yet, but will likely be the panel.

I will send you a link to the protocol doc.

 

[english_1969]

Hmmm,

I have this Honeywell model and I cannot find anything about it being controllable.....any more information on that?

I got stuck with these (although they are generally nice) due to the HVAC company not wanting to use anything else.

I am on a similar search to replace this unit with very similar needs (damper and humidifier control)

Thanks,
warren

 

[beelzerob]

I have this Honeywell model and I cannot find anything about it being controllable.....any more information on that?
I am on a similar search to replace this unit with very similar needs (damper and humidifier control)

Thanks,
warren

You have the IAQ 9421, or some other Honeywell model?

From what I've seen so far, it looks like the thermostat itself doesn't do the HA comms part...I think it is the *other* control device from honeywell you have to buy with it. That's what begins to bring the price up quite a bit.

jkish, can you find that thread in CQC again where someone talked about a driver? The only thread I can find on cqc forums is in 2007 where you asked about a 4 stage thermostat and mentioned the 9421. Other than that, where/how do you know about a "serial interface kit" for the 9421? I'd like to take a look at that.

 

[jkish]

I have this Honeywell model and I cannot find anything about it being controllable.....any more information on that?
I am on a similar search to replace this unit with very similar needs (damper and humidifier control)

Thanks,
warren

You have the IAQ 9421, or some other Honeywell model?

From what I've seen so far, it looks like the thermostat itself doesn't do the HA comms part...I think it is the *other* control device from honeywell you have to buy with it. That's what begins to bring the price up quite a bit.

jkish, can you find that thread in CQC again where someone talked about a driver? The only thread I can find on cqc forums is in 2007 where you asked about a 4 stage thermostat and mentioned the 9421. Other than that, where/how do you know about a "serial interface kit" for the 9421? I'd like to take a look at that.

Honeywell's control bus is called Enviracom. The Honeywell Enviracom Serial Adapter- W8735A1005, allows you to connect to the bus via RS232: http://customer.honeywell.com/Honeywell/Pr...aspx/W8735A1005

The CQC driver references can probably be found by searching for Enviracom over there. EDIT - looks like BPH might have been the one with the driver: http://www.charmedquark.com/vb_forum/showthread.php?t=2542

You can buy the thermostat + the interface box (not including serial adapter) pretty cheap via Amazon - http://www.amazon.com/Honeywell-VisionPro-.../ref=pd_sim_k_2 - and even cheaper on eBay

 

[sic0048]

You should have jumped on those RCS TR-40 thermostats on EBay when you have the chance! I picked up about 5 of them for both my parents system and mine. I paid anywhere from about $70 early on to $35 towards the end. Talk about a deal!

 

[beelzerob]

Awesome info, thanks! bph hasn't posted since late 2009, and was 6 months into his being laid off at that point, so I hope he's still around!

That's cheaper than it thought it was...and I realize that it is because if you scroll down on that amazon page, there is what appears to be the exact same thing but for like $100 more from another store, so it's hard to tell if it's two different products or not. I've got months before I'm going to need this thermostat, whichever I get, so I'll hold off on the impulse buy at this point.

 

[beelzerob]

You should have jumped on those RCS TR-40 thermostats on EBay when you have the chance! I picked up about 5 of them for both my parents system and mine. I paid anywhere from about $70 early on to $35 towards the end. Talk about a deal!

Oh, you know how it is....you eventually begin to suffer from "jump on this awesome deal" fatigue, and so you finally managed to pull together enough will power to avoid the temptation...only to have someone come later and throw it in your face again when you find you really should have gotten in on it.

 

[beelzerob]

Does anyone know if this honeywell thermostat is going to cause me problems if I get it off ebay or something? In other words, will honeywell not help me a lick if I have problems because I'm not an authorized dealer? I'm just concerned about a lack of any help after the purchase, whereas I know I could find plenty of aprilaire or RCS help should I need it.

jkish, do you happen to know exactly how zoning control interfaces with this? I understand that I'd need a separate zoning controller, and that would attach to that box that the thermostat connects to, and that the serial interface connects to. But then what actually tells the zoning controller what to do? Is it the thermostat at that point somehow? So far, I've not seen the IAQ 9421 indicate it can do zoning, in it's "features" list.

 

[jkish]

Does anyone know if this honeywell thermostat is going to cause me problems if I get it off ebay or something? In other words, will honeywell not help me a lick if I have problems because I'm not an authorized dealer? I'm just concerned about a lack of any help after the purchase, whereas I know I could find plenty of aprilaire or RCS help should I need it.

jkish, do you happen to know exactly how zoning control interfaces with this? I understand that I'd need a separate zoning controller, and that would attach to that box that the thermostat connects to, and that the serial interface connects to. But then what actually tells the zoning controller what to do? Is it the thermostat at that point somehow? So far, I've not seen the IAQ 9421 indicate it can do zoning, in it's "features" list.

I believe you use the zoning controller in place of the regular interface box. The zoning controller has your Furnace/AC/Heat Pump connections, damper control connections, and a Enviracom bus that you can connect multiple 9421 thermostats up to. The thermostat makes the call for heat/cool/dehumidifier/humidifier the the zoning controller talks to the dampers and HVAC equipment to make that happen.

See for example: http://www.alpinehomeair.com/_viewresource...0Product%20Data