Need Thermostat that supports Dual Fuel

[Tiki]

I purchased a Honeywell Z-wave thermostat - TH8320ZW1000 - earlier this year to work with Homeseer. All was going great until winter hit, then my HVAC (brand new installed last summer) started acting a little funny. After calling the installer I found out that the Honeywell Z-wave thermostat does not work with my system because it is dual fuel that uses an outside temp sensor to shut off the electric heat side ("locked out") when the propane heat is on.

I cannot find a thermostat, be it Z-wave, WiFi, or whatnot, that will work with a dual fuel system. Does anyone have any recommendations on a thermostat or am I stuck with my HVAC system not working with Homeseer? I honestly don't care how it connects as long as HS can control it.

I have seen an INSTEON thermostat - Venstar T1900 - that supports dual fuel systems. That seems like a long work around, but it might work. Can anyone confirm this?

My HVAC knowledge is limited, but I'm working with my installer on figuring out a solution. However, it's not looking good.

Also, I would like to stay away from any thermostat that relies on the cloud to function - i.e. Honeywell's WiFi thermostat, or RedLink, etc.

[sparkman]

Hi Tiki,

Looks like this z-wave thermostat supports dual fuel (with an accessory relay): http://www.smarthome.com/51205/Schla...rmostat/p.aspx. I have no experience with it and don't know how well if it integrates with HS. Out of curiosity, if you don't care how the thermostat connects to HS, what's your concern with the Insteon dual fuel thermostat?

Cheers
Al

[Tiki]

The only concern with the Insteon is I would have to purchase the thermostat, then a module for it to be accessible via Insteon, and then a module to hook up my HS computer with Insteon. All that for one device.

If I have to do that then I'm willing to, but I hoping for a more simple, less expensive option.

[Uncle Michael]

Have you looked at the Nest thermostat?

or the Trane?
http://www.smarthome.com/51205/Schla...rmostat/p.aspx
It says it has an accessory relay kit for dual fuel systems.

[rustynail]

First of all, I am not an HVAC expert. Last year I replaced my HVAC with a Trane duel fuel (natural gas/heat pump). I have this connected to a RCS TR60 Tstat, which is a 2 stage heat pump with auxiliary heat. When I looked at the specs for your Honeywell Tstat, they are very similar.
My workaround was
Capture the outside temp in HS (either by remote sensor or web feed)
Determine at what temp you want your unit to change from heat pump to gas ( In my case I use 40 degrees, but this depends on your location and cost of electricity and gas)
In HS set up logic to run only when the thermostat is set to heat mode.
When outside temperature is less than or equal to 40 degrees, then send command to thermostat to switch to emergency heat. This should cause the unit to go to gas only operation. Also add if outside temp greater than 40 degrees turn off emergency heat mode.
Hope this helps.

[Guest]

Similar to what rustynail has suggested - I believe that the Omnistat2 has the ability to do what you want. You will need the RC-2000 thermostat as well as the 23A00-1 outdoor temp sensor or to provide the data from homeseer using a different source. Personally I prefer to use a sensor attached to the thermostat as it doesn't depend on homeseer functioning. Unfortunately, my sensor (23A00-1) just quit but it is still the best option.

Thermostat web page:
http://www.homeauto.com/Products/Omn...t2Products.asp

Installation Manual:
http://www.homeauto.com/Downloads/Pr...ion_Manual.pdf

I use a RC-2000 with the driver for the RC-80 and it works well though some functionality is missing - namely the humidity controls and the ability to read the outdoor temp sensor. Still this is a great thermostat with lots of functionality and the new ones have Zigbee options as well.

[Tiki]

That's exactly what I was thinking of doing rustynail, however, my installer said that probably wouldn't work because thermostat needed to lockout the compressor to shutoff the electric heat side while the gas unit was running. He didn't think that would work with this thermostat.

Last I spoke with him, he actually brought up the Trane thermostat. He thought that would work with an adapter of some sort, but he was going to have to look it up or talk with another guy that's actually more familiar with them. Haven't spoken with him since, but I'm going to follow up soon about that.

[Tiki]

Just got off the phone with my installer to ask about the Trane thermostat, and why I can't manually set the gas side from Homeseer.

My unit has an internal dual fuel kit and the change over occurs in the thermostat. For the Trane Tstat to work, I would need an external dual fuel accessory, but he is not sure it will work with my unit and is checking on that. He stated they had trouble with the external fossil fuel kits, so they started putting them internally in the unit.

As far as the manual control from HS workaround, that won't work because the thermostat controls the relay to do the lockout with the internal dual fuel kit. So, even if I manually switch the thermostat to Emergency or Aux. Heat, the gas will come on, but it won't close the electric heat side.

[rustynail]

My unit change over occurs in the thermostat. The RCS TR60 thermostat is a standard 3 stage heating , 2 stage cooling with serial communication via RS 485 .You can check this out at

http://www.rcstechnology.com/oldsite...ats/serial.htm

Compare it's wiring to your Honeywell Z-wave thermostat. The difference in our installs could be the way the internal logic of the Trane duel fuel gas pack unit operates. (Trane 4DCZ6060)

climatesolutionsinc.com/.../Trane%204DCZ6%20Manual.pdf

When thermostat is in normal heat mode, unit functions as a two stage heat pump using the compressor for heating. When thermostat is set to emergency heat, the thermostat goes into stage 3 heat which is gas only operation. (no compressor and natural gas only). Gas operation is a function of the Trane unit when thermostat is in stage 3 heat mode (emergency heat)

You may notice that the Trane unit has four stages of heating while the RCS thermostat will only supports three. The Trane unit allows you to combine the two gas heating stages into one. Then logic in the Trane unit in emergency heat mode automatically goes into low stage gas heating for 10 minutes and if the set temperature is not satisfied, switches to high stage gas heating automatically.

HS changes the thermostat to emergency heat at 40 degrees or below, which makes it gas operation only. I used 40 degrees based on price of gas vs. electricity in Nashville.

[Tiki]

Just an update.... I feel like I'm going around in circles with this thing, but I think , I THINK, I found something useful. I finally found my invoice that has the model number of my unit - AUHMC100ACV4VA American Standard Platinum ZV Furnace. A website I found mentions it has AccuLink connectivity, which I think either works with or been rebranded to Nexia Home Intelligence (also on their website). Which is the rebranded name for the SchlageLink line of products and services.

On another website, I found the thermostat my installer had mentioned - AZEMT500BB32MA, however, I can't find this anywhere online to purchase. In the documentation, it mentions dual fuel operations. This thermostat is similiar to the one found on HS website TZEMT400BB3. Best I can find is that for dual fuel to work with this thermostat, an accessory relay kit is needed. Back on American Standard's website, there is a thermostat that looks like this one - model AZEMT400B. I can't find much about this, but now I'm curious if this one and the one on HS are similar and if so, I bet it might work.

[Tiki]

Update: I finally found a thermostat that would work and had it installed. All is good.

The thermostat that my installer suggested, azemt500bb32ma, was basically the only thermostat that would work.

[CharlieWayne]

I'm a little late but I wanted to share about the Venstar T1900 with Insteon module. Insteon is my main lighting and ceiling fan protocol so that limited my thermostat choice.

I bought the Venstar T1900 after long reviews of the manual. Its packed with features I plan to use such as extra outputs to send signal to a whole house dehumidifier, adjustable second stage cut in/out temps, and lots more to make it short.

The only thing I don't like is how the Insteon Module hangs below the tstat. My intent is to make a small extension wire and push the module into the wall where its hidden. Also I'm planning on painting my tstat trim plates the same color as my wall to blend it in more.

But again like u said that would be a lot of money to set up Insteon just to run a tsta.