Should I try to use HA for HVAC control?

Hello everyone. I am a newbie to HA and am just dipping my foot into the water for some help to know if this is something I could even try to go down. I am interested in installing some inline duct fans to my HVAC system and I wanted to be able to control them both in terms of how fast they go and their on/of. I am hoping to be able to use some sensors in different parts of the house to help make decisions on if they should run or not. I could set up a pressure switch that would turn them on and off but it would be nice to get better control based on the rooms needs. I was thinking of using
https://acinfinity.com/inline-fan-systems/
As they are very easy to get and seem to have more options than just on and off.
Thanks so much for any guidance you can provide.

Steve

Personally, I like my HVAC systems to act autonomously (via a dedicated HVAC control system), with allowed input from outside systems. This will allow the HVAC to function correctly / safely in the event of an outside control failure.

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I agree with servicexp to a point. I have a home and a condo. Sometimes when the kids use the condo they don’t attend to the hvac system. Worst yet - they think the electricity is free - setting the set point at 69 and spending the remainder of the day at the beach. To that end I have a smart thermostat that I can communicate with ha and a bash script talking directly to the thermostat to test the settings every hour. If the set point exceeds a specific value the script sets it back. That way I don’t need stock in the electric coop. Further - moving between the two places I can get the environment prepped for our arrival using ha in either house.

Good luck.

My Lennox hvac has a variable speed fan, I’ve created algorithms to dynamically adjust the fan speed. So if I’m trying to move more heat from the wood stove around the CFM goes up. Zooz has some really small zwave temperature sensors which I put in the duct intake and several registers.

Those inline fans look interesting. The first thing to figure out is how they affect the overall balance of the HVAC system and if it will remain balanced. The second is to figure out what’s the worst that happens if the fan never turns off because HASS has crashed.

In my case I’m just supplying a new input to the Lennox hvac controller (target fan CFM) and it runs the control.

I had a similar situation. I bought a normal “dumb” duct fan for one stretch where the duct to a remote part of the house is insufficient. I plugged it into a smart plug which is controlled via HA.

I wouldn’t want something a critical as my heating and air conditioning systems dependent on HA. But I do have my regular smart thermostats integrated with HA, and that’s how I typically change them. Because of this, I was able to set up an automation to turn on the duct fan when the HVAC blower is on, and again five minutes after it turns off. If HA were to fail, no real harm done. The rest of the system would still work, just this booster fan wouldn’t go on or off at the right time.

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Thanks everyone for the follow up. I really appreciate it. It seems like a few of you mention “IF” HA crashes…I guess I had not though about that and really wonder how often this happens. I am thinking I like CaptToms idea of a dumb smart plug to turn the fan on or off and then use something else to control when it comes on. Thanks for the idea of other temp sensors that could be integrated into the system.

Are there any controllers that can control an EC motor that work with HA?

Admittedly, my background is in critical production systems, so I may sound cynical here. HA isn’t typically installed with 100% reliability in mind. The hardware is generally hobbyist-grade, consisting of something like a Raspberry Pi or a second-hand machine someone had lying around. From what I’ve seen, it’s expected that the user will be continually tinkering with it. There are a large number of version updates every month. It’s highly dependent on a fairly tall stack of software and hardware all working together perfectly, while frequent changes are being made.

This is not to say you couldn’t build a bullet-proof system and rarely update it, but that’s not the way HA is intended to be used. I have my RPi on a UPS and my system survived a 25-hour power failure during which generator power went up and down several times, and was generally very dirty. Still, in all that, the last thing I’d have wanted to worry about was the HVAC system failing. My off-the-shelf thermostats keep things going. I never even looked at HA until everything was back to normal.

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