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Thermostat allowing cloud control of erv?

tupchurch | Posted in Mechanicals on

I have a Honeywell TH8321WF1001 thermostat at present. I like being able to control its functions via app and that it sends me a monthly usage report , though it’s not super detailed. I plan to soon install one of the Broan AI ERVs and was wondering if there was a good smart thermostat somewhere that could integrate control of the erv and air conditioning? My ultimate goal would be to have the cfm of the erv controlled by CO2, which is one of my main troubles in my house, but, failing that, I would accept the ability to change cfm by app after I look at my IAQ readings. I have looked at Broan Overture, but it seems too expensive for too little control (only turns on boost automatically rather than adjusts cfm dynamically).

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  1. DennisWood | | #1

    To my knowledge, no one adjusts the CFM dynamically, other than balancing to a set air flow. I had to create a system with two ECM fans, temp probes of the four air streams, inside IAQ sensors....and automation. Broan's use of the "AI" term is a bit misleading based on what it does currently.

    As far as thermostats, the only one that I'm aware of that can be integrated directly to an ERV is the Ecobee 4 but that is a bit limited too. You can set hourly run times and the stat will run the air handler/furnace fan with the ERV (it also accounts for system runtime) to get to a given target. It doesn't have an extra set of contacts for boost, so it get's a bit messy if you want to automate that, along with a furnace interlock.

    My suggestion is that you purchase an ERV with the highest efficiency you can find, then dial in the ventilation rate right around where needed as a minimum. Then automate the on/off as well as boost based on CO2. You should take a close look at also monitoring VOC and Radon to ensure that the ERV only turns off when all three values are low. This way you have a system that works fine out of the box, but has added functionality that can be easily removed if needed.

    I've been playing in this sand box for eight years now :-) Fully automating a system with the defrost damper, defrost cycles, drainage(HRV) and ECM fans with full speed controls is 100% doable, but it is a time suck to set up. If your temp never goes below -10C with an ERV, then it is simpler for sure.

    1. tupchurch | | #2

      Thank you. I have been thinking of trying to use IFTTT with input from my airthings. I could use that with at least a smart plug to have it turn on and off, right? Just hesitate to add a monthly subscription.

  2. DennisWood | | #3

    I would not do any automation around an ERV/HRV cloud based, if you can avoid it. You can do monitoring with an Ecowitt WH45 (which can be 100% local on your LAN) for CO2, PM2.5, PM10 and ideally using a hub like Hubitat to do any automation around...again not cloud based. Then you can add a few dry contact relays (like the Zooz Zen51) to manage on/off and boost. A system like that will allow wireless control, and work without internet if desired. Most hubs, Hubitat included, will allow remote access to the system via dashboards etc. to both monitor and control away from the home.

    Once you get a hub, then you can add bits as you see fit to manage things like motion lighting, Christmas timers, water sensors and shutoffs etc. IFTTT on the surface is great, but there are too many variables to manage around reliability in my experience.

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