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Variable Speed HVAC Thermostat Advice Please !


BigMojo

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Greetings, first time caller, long time listener, 

I just contracted to have our central AC replaced with the following:

American Standard AccuComfort Platinum 20 Heat Pump (Variable Speed)
American Standard ForeFront Platinum TAM8 Air Handler (Variable Speed)
American Standard AccuClean Whole House Filter
American Standard AccuLink Platinum 950 Control

 

American Standard/Trane are identical other than branding.

I'm running an ISY994i/IR PRO (with only the Open ADR module active)

My goal is to fully integrate this equipment without losing any of the AccuLink functionality as this would seriously compromise both the energy efficiency and house filtration efficacy.  I'm not interested in a paid Nexia subscription. 
 

I have virtually no aversion to adding software modules, hardware devices or another AccuLink / Insteon / Z Wave compatible thermostat.  I'd prefer not to use a Rasberry Pi or any other full time PC based solution that would negate using the Admin Console/Dashboard as my single administration point when offsite.

 

Are there any other factors that I need to be aware of?

 

Has anyone succesfully implemented a solution that meets my goals?

Thanks in advance for all responses, I'd like to get a solution nailed down and shipping ASAP !
 

 

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The AccuLink thermostat is a Z-Wave compatible product. Both Nexia and Schlage are mentioned with the literature. You should be able to integrate the thermostat with an ISY using the Z-Wave module only.

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If your TSTAT can not communicate via Zigbee, Z-Wave, Insteon, then no. If the TSTAT has an open API and can be communicated via the ISY Series Controllers network module you might be able to do something.

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Thanks for the quick responses Stu & Teken. Oddly enough the Nexia FAQ is the only place that actually documents the Z Wave functionality of the AccuLink Platinum 950.  I feel a bit silly now but I'd have thought the actual spec page for the device would've cited it lol.

 

I'll update my success or failure upon installation and thanks again!

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I think that thermostat is a wifi based thermostat that is able to talk to the nexia bridge. Nexia products that are zwave normally state zwave. everything on that particular product cites wifi. Nothing says zwave. I would contact the manufacturer to see if it really uses zwave

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I think that thermostat is a wifi based thermostat that is able to talk to the nexia bridge. Nexia products that are zwave normally state zwave. everything on that particular product cites wifi. Nothing says zwave. I would contact the manufacturer to see if it really uses zwave

 

I agree because often times even if a manufacture supports a HA Protocol they invariably lock it down where you must use their system(s) to make use of it.

 

This is why I indicated even if it supports Z-Wave but you later find out its locked out and must use it via the Nexxia Bridge etc. If they have a open API that can access the TSTAT this would offer you another method via the ISY Series Controllers network module to do some basic / advanced adjustments.

 

Keep us all updated as I am sure this information will prove helpful to someone else down the line.

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  • 1 month later...

Sorry for the long delay, HVAC Equipment was back ordered and it's been a crazy month since then. I'm digging hard for a real answer from Nexia & American Standard/Trane and have been receiving some serious contradictions from them. Some of their Tstats have the Nexia Bridge built into them while others do not.

Nexia refused to search their tech notes for any ISY references so I asked for a list of "true Z-Wave" devices and was advised that the models are:

Mdl#   Amer Std.                      Trane                          Nexia Bridge? Accu/ComfortLink?
500B  AccuLink Control             Home Energy Mgmt.    NO                     NO (Note name! )
624    Silver 624 Control            XL624                         NO                     NO
824    Gold 824 Control             XL824                          YES                   NO

The two remaining top of the line thermostats (not represented as Z-Wave) are:

850    AccuLink Platinum 850    ComfortLink II XL850   YES                    YES
950    AccuLink Platinum 950    ComfortLink II XL950   YES                    YES (Installed)

The documentation has some profound inconsistencies in both product names and functionality claimed as seen on these pages:

http://www.americanstandardair.com/products/thermostat-controls.html
http://www.americanstandardair.com/products/thermostat-controls/silver-624-control/_jcr_content/product_brochure
http://www.trane.com/residential/en/products/thermostats-and-controls.html
http://www.nexiahome.com/compatible-products/

This is beginning to look like a bait and switch where sales (documentation) promises one thing and tech support gets to deliver the bad news. Nexia emphatically states that my 950 isn't and won't behave as a native Z-Wave device but states the 824 will. I've got 3 issues with their claim:

1. Why would I believe a lesser product has greater functionality than the top of the line unit already installed?
2. Why would I be pointed at models that don't support AccuLink bearing in mind the tech support rep was live monitoring my system data stream during our discussion?
3. In the http://forum.universal-devices.com/topic/13513-trane-xl824-thermostat-w-zwave-nexia-support/, Michel's final post dated 6-Jul-2014 sounds terminal unless there's been major changes to the bridge functionality since then.

I'll be escalating this with American Standard and updating upon further developments.

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I just updated by heating and A/C and they tried to sell me a Lennox system with the iComfort thermostat. This thermostat provides all the communications between the furnace and compressor like the American Standard system you mentioned. However, the thermostat does not talk Z-Wave, only WiFi and no API for the thermostat is available.

 

However, the furnace and A/C can be configured to work with a regular 2 stage thermostat so I stayed with my Honeywell Z-Wave thermostats. The only thing I really lose is the ability for the system to send diagnostics codes directly to my installer in case of a failure. I think this is a good thing since it frees me to choose whoever I want to service the system in the future. Moving from a system with single stage to dual stage heating and cooling was the hardest thing to get used to because I like to know when the thermostat lkcks in the second stage which you can only find out by observation.

 

While the ISY does include trigger points for the second stage coming on, alas the Honeywell does not send those messages.

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Sure. Heating & Cooling systems, or combinations of one or both can have 2 stages. The first stage (for heating) involves a lower energy consumption (in my case gas) and blower speed. If the desired temperature is not reached in a certain length of time then the second stage is invoked which turns the heating to full power using maximum gas and the highest blower speed. Once the desired temperature approaches it backs down to the first stage. The same is true for cooling.

 

Difference thermostats work in different ways. For example the Venstar thermostats have programmable first to second stage parameters like time. My Honeywell thermostats don't have anything programmable regarding the stages and appear to be temperature based. If the desired temperature is more than one degree away it seems to invoke the second stage and backs down to the first stage when the temperature gets close to the desired temperature. Mostly you can hear the difference when the fan increases and decreases in speed.

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That's true Andy and I echo both of your thread entries. I had two new Carrier units put in last fall. Zoning and variable speed control were the only features on the advanced carrier thermostats that I didn't have. I don't have zones, and I could not get enough evidence of the value of variable speed for my installation.

 

I have 2 Venstars and had stage 2 configured differently in 2 parts of my house last winter. The older part of the house is getting its long overdue insulation upgrade right now, but to get through last winter, I needed to have it call stage 2 more quickly than the newer part of the house. This winter, the settings will be closer for both parts of the house. The venstar API, for the colortouch models, reveals when the second stage has gone active, so I can monitor and track that.

 

For me there was a counter to the variable speed control feature, which is regular fan cycles. Because we have allergies, I have Hepa 13 filters and have an ISY program that runs the fans 15 minutes an hour, starting an hour after the last cycle finishes. In addition to filtering, this also keeps the temperatures more even throughout the house.   I could not make the case for Carrier branded thermostats managing variable speed fan control. And i get all other functionality of the Carrier branded Thermostats, and more.

 

Newer HVAC units can make the stage 1 / stage 2 call based on the return air temp, and will work with non-2 stage thermostats. If you love your thermostat and it doesn call stage 2, that may not be a problem. My units can be configured this way.

 

If I had zoned systems, I would probably feel differently

 

Paul

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Paul,

 

Do each of your thermostats control different HVAC units? BTW, some units have as many as three stages of heating and cooling B)

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Hi Stu

Yes, my house is in 2 parts; the original colonial structure built around 1950, and an addition added I think in the 80's. Each has its own ducting system and hvac system. We're only around 2300sq, and a single system with dampers sounded attractive but proved to be impossible to implement based on the nature of the house... without major surgery.

 

The old part of the house suffered from 1950-itis, no insulation in the walls, which is being addressed right now. When I put new furnaces in the house last fall, I undersized the one in the old part of the house from the previous unit, knowing I would be solving the sealing and insulation problem this spring.  So the furnace for the old part worked very hard last winter, and I let it call second stage much sooner.  But its expected to get a break now that real problem with insulation is being addressed.

 

I've heard of the additional stages!  The venstar color touches allows control of a third heat stage, but I can't use it.

 

Paul

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 Mostly you can hear the difference when the fan increases and decreases in speed.

 

Thanks for the clarification on that point. For what ever reason I was thinking about something completely different than what you initially wrote.

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  • 1 month later...

Thanks for all of the input from everyone.  I was able to get through to Nexia escalation which was quite helpful and forthcoming in the end.  The upshot is that despite being a premier Z-Wave Alliance member, Ingersoll hasn't committed to enabling Z-Wave within their product lines.  This is due in large part to their desire to protect/promote the Nexia service as an income stream.

 

They did admit that this lack of functionality has been the source of some buyer's remorse and pushback.  It is under discussion at the management level on whether to deploy a true Z-Wave solution, but for now there is nothing they offer that supports the communicating or multi-stage HVAC systems, so Caveat Emptor for now.

 

For those using HVAC systems from either Trane or American Standard, increased visibility would go a long way to motivating the deployment of a true Z-Wave implementation, I encourage you to email them:

 

contactnexiasupport@support.mynexia.com

 

Thanks again for everyone's support and I'll update on any change in status.

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Hi BigMojo,

 

Sorry I missed your message in May. I have been busy installing more insteon devices trying to get rid of the last of the X10 gear. I have the ComfortLink II XL950 with my Trane furnace and ac and I never did get it working with the ISY although I never tried very hard. I had the system installed last summer and at that time I searched online to see if it was linkable but never found anything. The free version Nexia app should let me access the temp settings remotely but it never worked properly for me last summer. I could see some basic temp settings with the app but was not able to change anything. Before I could sort this out though the 950 died (black screen of death after a month of operation). The dealer replace it and I have had no further problems but I have not retried the Nexia app.

 

My furnace is the modulating type (continuous stages) and the ac is the variable speed model.Because of that there are I assume" smarts" or algorithms in the thermostat firmware that controls what speed/level to run the units at depending on inside/outside temperatures and interior temp delta from set point. I am not sure not how much of this I want to interact with from an automation perspective on the 950. I would not mind using the ISY to adjust set points or to switch modes but adjusting speed/output level not so much without understanding more about the logic the thermostat uses for this. I am very happy with the system so far. The outdoor ac unit is very quiet and the temperature inside the house is much more constant and even than it has ever been. Because of this I find that I can set the summer temp a few degrees above what I used to use.

 

Sorry I couldn't be more help. If you do get linking to work please post and let me know

Gary

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