Control Panasonic ERV?

[hubitrep]

@calinatl

if the area is unoccupied, CO2 remains relatively stable?

CO2 will decay according to your house's natural air exchange rate (even with the ERV off, there is always some leakage) and should eventually settle to the outdoor value, which is around 420 ppm at sea level.

@calinatl

I would not want high CO2 readings to trigger the ERV when the area is not occupied as that would be wasteful

Depends on your objective for using an ERV. In my case I want to ensure sufficient fresh air supply and have it set up to keep CO2 levels below 1000 ppm at all times. The HRV turns off only when CO2 goes below 600 ppm.

Come to think of it, your use case might be a bit tricky to balance as this is not a whole-house setup.

[denwood]

@calinatl , driving based on C02 will work, and this is what I do. I would add that I also track VOC and Radon and drive off those levels as well.

If you just want CO2, I'd get the Ecowitt WH45 (sensor with CO2, PM2.5, PM10, temp, humidity) and Ecowitt GW1100 (LAN gateway) which can run from USB power and requires no web api...using local communication from gateway. It's been 100% reliable. ~$150 USD for both.

If you want to also monitor Radon, VOC and CO2, the best bet there would be the Airthings View Plus ( View Plus | Airthings ) which has a WIFI gateway built in, and can run from USB power. This needs a web api though to work. I have three of the Airthings Wave Plus, one on each floor. These require batteries and need a separate WIFI gateway so I'd go with the View Plus. These devices are not as reliable as the Ecowitt WH45.

Both of the above have Hubitat integrations.

Keep in mind that with a max of 35 CFM supply, that Panasonic will likely need to be running 24/7, something you'll see when you start monitoring. I believe you have another ERV running in the home correct? In that case, a sensor in the spot ERV occupied area will work fine. Having four CO2 sensors in my home, I can tell you that CO2 accumulates quite quickly in occupied areas. A "perfect" whole home system would have fresh air supply to main living areas, bedrooms, bath and kitchens and 0-10V dampers to control supply to where it is most needed.

In any case, I have extensive experience now with demand controlled ventilation as my two HRV ECM fans are controlled pretty much by CO2/VOC/Radon levels, and the HRV is integrated with the kitchen exhaust EC fan (for makeup air)...also automated to the induction cook top. I should be able to address most of your questions in that department

@hubitrep , my thoughts on CO2 demand driven ventilation have changed a bit once I started monitoring Radon and VOC as well. I only shut down the system if Radon is below 150 bq/l, VOC below 200 ppb, and CO2 below 500. This rarely happens. I found that when I shut down the system on CO2 below that 600 range, then VOC and Radon would spike. My system is based on EC fan control (2 fans for supply/return on an HRV) so will toggle through 50, 65, 75 and 90 CFM ventilation rates based on what's going on with VOC, Radon and CO2.

[calinatl]

@denwood Thank you - as usual great information.

I do have an Airthings Wave Plus for another area of the house, but am not thrilled with it. The data can only get off the device via bluetooth, via its phone app, ASAIK. I did not want it on a phone that travels with a person, because if the person(s) are not in the house, the data won't transfer. So I put it on an old phone that stays in the house. But that also won't sync unless you manually turn the phone on and open the app. Thus I've been considering moving to the newer device that has both a wifi connection and a info screen.

Had not considered the Ecowitt. Will look into it as the local aspect definitely appeals to me.

The downside of the Airthings device is that the data has to go up to the Airthings servers before Hubitat can download it. The upside is that Airthings is the only device I'm aware of that will report Radon readings to the Hubitat.

Presumably radon readings are most important on the first level of the house, so I could use Airthings on Level 1, where the ERV runs 24/7/365 and use Ecowitt on the upper level where I'm trying to control the ERV. Not sure if there is any downside to the devices not sharing the same platform...

[denwood]

Airthings Wave Plus can report to Hubitat, but you need to purchase their wifi gateway (hub) and pair the sensor to that. I have three AT Wave Plus devices paired to an AT hub and they sync every two minutes. At this point you can check in on the sensor via your phone anywhere…bluetooth will not be used by the sensor as your AT Wave Plus will connect to the AT hub using RF. Once you have the AT hub installed, then you can install the integration in Hubitat . Hubitat will use the web api to pull the AT hub data from the cloud…clumsy but it works fine. The upside then is that anyone with the AT app and your login can check in on air quality.

Hub

You are correct in that radon reports to Hubitat are pretty limited with respect to products. Your control plan sounds good. Radon levels will be highest at your lowest level…for us, the basement.

You can use both Ecowitt and AT on your setup. I actually average the CO2 sensor values to arrive at a variable to use in my automations to cycle through the 50/65/75/90 CFM profiles. This way the upstairs sensor will bias the house average higher at night (bedrooms all upstairs) and tends to bump vent levels.

[hubitrep]

@denwood

my thoughts on CO2 demand driven ventilation have changed a bit

How interesting. In fact the initial reason for getting an HRV for my 1950's house was to control radon, which was right at the margin of what Health Canada considers safe. It did help, but I wasn't satisfied so I had a sub-slab ventilation system installed, which completely eliminated the problem. The HEPA-equipped HRV I selected brings additional health benefits by diluting respiratory particles in general. I get the idea of ventilation based on VOC (for cooking fumes mostly?) but I have not yet automated our range hood so probably not useful in my case.

@denwood

will toggle through 50, 65, 75 and 90 CFM

Here, the stock HRV unit essentially turns off when no one is home, runs on low speed (50 CFM?) most of the time, on high speed sometimes when we're all home, and as a last resort the bathroom extractor fan turns on to be used as a poorman's makeup air (I know, it's not really ) when 100 CFM of fresh air isn't enough. I might use the new Airplay integration to shout "open a window!" if all else fails

In our cold climate, an HRV can create a low humidity situation (should have sprung for an ERV instead, I guess) which I need to correct with humidifiers... quite the rabbit hole

@calinatl

The downside of the Airthings device is that the data has to go up to the Airthings servers before Hubitat can download it. The upside is that Airthings is the only device I'm aware of that will report Radon readings to the Hubitat.

Correct. I use 1 View Plus, 1 Wave Plus and 1 Wave Radon in my house. I am not a fan of the automatic baseline calibration algorithm used on the View Plus so generally don't recommend it unless you need the radon reading. The Awair Element is a better product IMO (still a cloud API). I've never tried the Ecowitt, sounds interesting. An acquaintance of mine builds good quality CO2 sensors and one of his models offers a local LAN API, although most of the models go through a cloud API : https://co2.click. I use one of these for DCV at a second location (model C).

I was really hoping the new IKEA IAQ sensor would offer CO2 readings, but it does not.

[denwood]

@hubitrep , I hear you on the humidity thing as I’m in zone 6A here in Canada as well. I do need to swap the HRV core for an ERV version at some point as yep, at -30C, it gets pretty dry. I basically gutted an old Venmar HRV and use dedicated supply/return EC fans exterior to the HRV. They are controlled via 0-10V and Hubitat.

I would agree 100% with your radon comments too. I’m around 130 Bq/m3 (house bill in 1905) and the HRV lowers it but not as much as I’d like. I’m on the verge of doing a dedicated mitigation system from the sump.

VOCs are less from cooking (the kitchen exhaust is very effective) but more from things like candles, the girls hair products etc.

The Ecowitt WH45 and their WIFI gateway (required) is very cost effective and has been flawless with respect to CO2, PM2.5, PM10 sensing integrated with Hubitat...highly recommend. @calinatl , it would be my pick for ERV control.

[calinatl]

@denwood

Airthings Wave Plus can report to Hubitat, but you need to purchase their wifi gateway (hub) and pair the sensor to that.

I think that is one of the ways to get it reporting to Hubitat. According to this Airthings site, any of the View monitors can also work as a hub.

Wave: understanding the connectivity and compatibility of your Wave |...

My Wave Plus is reporting to Hubitat, via only a bluetooth connection, but as I noted above, I have to manually open the phone with the Airthings app, and manually open the Airthings app to initiate the sync. I'm sure some of the folks here could figure out a way to automate that but I'm not one of those folks.

Anyway - goal is auto connectivity of Wave Plus & CO2 measurement in upper area:

• Airthings hub is $99, but that only gets me automatic connectivity to existing Wave Plus.
• Airthings View Plus is $299 but gets me a device that accomplishes both, along with another Radon reading and a screen, but via web access
• Ecowitt (device & hub) is $153 and gets me CO2 measurement in another area without web access. I could buy it and the Airthings hub and spend only $252, or throw in the Ecowitt for another $20. The only thing missing would be Radon at the upper area, but more data would be local, and the Ecowitt hub apparently has other uses. However, then I've added two more hubs to my growing collection. So annoyed that all these mfg's require an external hub...

Or I could just wait for a decent, low cost, reliable & local Zigbee or Zwave Co2 sensor...a person can wish.

There is a whole other path that may or may not become viable

• The Aranet4 device, as recommended by Allison Bailes of Energy Vanguard, is $186, but apparently communicates direct with Homey via bluetooth. That makes me wonder if HE will ever have an opportunity for a bluetooth receiver. I suspect the Aranet is quite accurate.

[denwood]

Ecowitt does have a web portal (free) which would give you external access via phone or web to sensor data, historical, graphing etc. You don’t have to set the web account up as Hubitat communicates directly with their wifi gateway via your LAN. Mostly I view this data via a Hubitat dashboard which gives you another method to view sensor data remotely.

You’re correct in that the AT View Plus has a hub built in. The hub only made sense to me as I was able to pick up the AT Wave units on sale…and there are three in the house. If you want to use the AT WAve sensors for ERV control, you’ll want them connected via a hub so they get polled and report to Hubitat every 2 minutes. Bluetooth is not practical as you’ve already suggested

[calinatl]

@denwood
Thank you for the advice. Much appreciated and much to consider. I particularly appreciate your info on how to connect the WavePlus to wifi to force continuous communication to HE.
Really wish someone made a reliable radon sensor that communicates locally...