Will Ecobee Work on a WaterFurnace Intellizone? Yes & No

I have been asked this question many times and its a complicated question with a complicated answer. The question is: Will the ecobee work on an intellizone zoning system made by WaterFurnace?

The answer is yes… but it can also be no.

Lets start with an important disclaimer note: I do not speak for WaterFurnace and I do not speak for ecobee. I am relaying my own personal experience having helped install intellizones and ecobees. What worked for me may not work for you and I give you ZERO warranty on any and all statements within.

You screw-up your intellizone or your ecobee its on you! That said everything that I write hear you can verify on your own quite easily.

Does ecobee work on Intellizone?

I think the easiest way to answer this one is to simply point out on my own Intellizone I have ecobee thermostats and they work just fine.

So does ecobee work on Intellizone? Yes it does. Hundreds of WaterFurnace dealers across the United States and Canada are using them and you can bet if they were all having problems those of us who are HVAC nerds in the industry would have heard about it.

So then why are people complaining that it does  not work for them?

Although ecobee works on the Intellizone I have heard of 3 cases where it did not work. One of them I was able to resolve but the other two are still ‘on going’ cases which I am working on.

On the one that I was involved with directly and was able to resolve the symptom was that the ecobee was telling the intellizone to come on even though there was no actual heating call. Needless to say it was quite interesting to me and very irritating to the installer / consumer.

After doing a bit of investigating we discovered that the AC voltage powering the Intellizone was much higher than it would normally be. As soon as we discovered this we got thinking, what if its voltage leak across the relays causing the problem?

ecobee PotentiometerIn an effort to fix the problem we installed a potentiometer on the power going into the intellizone and dialed the voltage down and low and behold the problem went away.

A potentiometer /pɵˌtɛnʃiˈɒmɨtər/, informally a pot, is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.[1] If only two terminals are used, one end and the wiper, it acts as avariable resistor or rheostat. – Wikipedia

Now obviously not everyone is going to have a potentiometer much less know how to install one so I went back to the drawing board of ‘ideas’ on how to fix this voltage issue. We came up with all kinds of neat ‘MacGruber’ fixes but none of them are ones I want to particularly list in a blog post for fear of somebody completely annihilating their ecobee or zoning system

What we think was happening is that the over voltage of 27-29volts AC in to the intellizone was causing the Varistors on the ecobee to leak voltage and that small amount of voltage in some cases was enough to make the Intellizone come on.

I say in some cases it makes the intellizone come on because although we saw it in the field I was not able to reproduce the problem on my own intellizone with ecobee’s controlling it.

What ecobee is my best bet for Intellizone?

One of the things I like most about ecobee is the fact that they engage with their partners and when they found out that their might be an issue they jumped to find a way to address it;

In response to the issue the ecobee Engineering team made the following change;

A while ago we noticed that HVAC systems had supply voltages of 27-29VAC instead of the 24VAC standard. So we changed the Varistor from a 30VAC part to a 40VAC part.  This was only done on the Smart SI and EMS SI products.  Therefore, we believe newer Smart SI and EMS SI should not exhibit this issue with intellizone panels.

A Varistor is a protective device used on low-voltage ac circuits like the relays you will find in an ecobee to limit transient overvoltages and current. In a nut shell it protects the relays from burning which shortens their lives.

So if you want to use an ecobee on an intellizone your best bet is to order an ecobee SI model with the particular caveat that you want one that was made AFTER March 2013 which is about when ecobee upgraded the ecobee SI hardware to have a beefier varistor to address issues of HIGH voltage

With any luck this will help you with your Intellizone issues.

Remember ladies and gents, meddle at your own risk and be aware that in doing so you may void your manufacturer’s warranty in the process. 



  1. Thank you so much I have been struggling with getting my intellizone (model ZCK4) to work with Ecobee (EB-Stat-01) for years, I tooks out the varistors but have not tried your solution – will it work with EB-Stat-01 and ZCK4. Any better/new solutions Thanks

    1. FYI David if you muck with your intellizone you will void its warranty. Unfortunately because of the design it may never work properly. It is not a design flaw it. The easiest comparison would be it is like trying to hook a MAC up to a PC.

      1. Do you have any new suggestions for wifi thermostats will work with Waterfurnace. GEO System 1: Two zone Nsh036 and Intellizone ZCK4 ; System 2:NSZ022 no zoning Thank you

      2. I continue to be an ecobee advocate. I know that contractors have been putting the ecobee3 on the Intellizone system with success. Another really slick item to checkout is WaterFurnace Symphony which takes the concept of an ecobee and completely internet enables everything on the geothermal unit. Compatibility will be a problem depending on the FULL model of your units ( need to know the letter after the NSH036 portion of the model ). Symphony is in a word, slick.

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