I have not yet purchased a Hubitat Or any other home automation products. I am convinced the Hubitat is the best system for my requirements, but I have some questions. To begin with:
If I have the Hubitat Elevation, why should I even need a thermostat (smart or otherwise)? Why not let the Hubitat use a combination of thermo sensors and switches to control the HVAC system directly?
Thanks.
Jack
Because if/when Hubitat crashes, or your WiFi is unavailable, you would have no heat or cooling. Same thing when you do upgrades.
Bad idea to put anything "essential" on any home automation hub.
What if the hub locks up/crashes while heat is off? You OK with heat never turning on (frozen pipes, etc)?
What if the hub messes up while heat is on? You OK with a 100+ DegF house?
additionally, the following are also pertinent...
A thermostat provides a user interface for convenient manual adjustments and current settings, no amount of rules or logic are ever going to nail set points for every conceivable situation.
Battery sensors for the primary temperature readings wouldn't be a good implementation, batteries do not last forever.
By the time you've built and installed all the components to deal with the above issues, you will have spent way more money in components and time than the cost of a decent home automation thermostat.
Obviously with Hubitat you indeed could do this, but these types of systems are best created when there aren't any available devices that provide the required functionality.
Plus, I'd like to add...thermostats are built to control your HVAC system and are tested to make sure they don't fail and if they do, won't cause the HVAC system to fail. I am always hesitant to DIY a solution on a system that can kill you if it fails badly.
What do you know about frozen pipes? 
I didn't always live in Texas. 
Also, I also realize the only example I used is the hub crashing.... What about if you get your user logic wrong?? That has been known to happen, too.
I guess knowing about frozen pipes could be a reason to move to Texas. Why am I still in the frozen north??
Great answers, thanks everybody!
So I need to select from thermostats that are compatible, but don't require any cloud services.
Jack
I'm pretty happy having Hubitat completely run my thermostat I've been fine tuning the details and so far has worked flawlessly. Goodbye Ecobee
Then I deploy my backup hub, restore the database from my current hub, and I'm back up and running withing minutes.
But you still have a thermostat in your setup, correct? The OP is asking about having a system directly controlled by HE via relays and eliminating the thermostat all together.
Yes I do. Not sure why one would consider going that route unless maybe it's a brand new HVAC install with no existing wiring. If the existing thermostat is already there and wired why not use it. I'm literally accomplishing the same thing as what the OP is asking, but just using existing equipment wiring and the thermostat itself as the relay.
Exactly.
I read a post somewhere about a guy wanting to eliminate all his light switches and using motion sensors only. One thing people don't think about is building codes. I'm pretty sure codes require a thermostat. Not that a lot of people care but in the sale of the house, it might become an issue.
That's the main reason I live outside of a city, because I will never care about building codes. That is how the majority of outside of city houses are built and routinely added on to is by DIY'ers. Building codes are solely aimed at protecting contractors from competition of DIY'ers willing to charge less $$$.
I think you will find building codes arose from unscrupulous contractors and incompetent DIY'ers.
If I choose to hire one of those it was my decision and thereby my fault. I should always be given that choice to hire them if I that is who I want doing the work. Preventing them from doing so takes away the low cost choice and institutes a one size fits all minimum standard, which has no choice.
I'm done ranting now, time for coffee
Not when a fire in your house could also destroy your neighbor's house and also costs the taxpayers money for the fire department to come and put it out. We don't live in a completely free society. This isn't Ayn Randville.
Not if you're on vacation or not home you don't... Last hub crash I had, I was in the UK.
But I agree that it is up the the end user to decide what is ok/not ok for them - up to, but not violating building codes.
My original question was answered quickly and answers were really helpful. I'm encouraged to see such an active support community for Hubitat. [quote="waynespringer79, post:12, topic:24978, full:true"]
Yes I do. Not sure why one would consider going that route unless maybe it's a brand new HVAC install with no existing wiring. If the existing thermostat is already there and wired why not use it. I'm literally accomplishing the same thing as what the OP is asking, but just using existing equipment wiring and the thermostat itself as the relay.
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I have existing wired thermostats, but they're old and dumb. I assumed I'd have to replace it with something, and since I'm not yet familiar with HE's capabilities, I was afraid "smart" thermostats might be overkill. But you (all) cleared that up for me.
Some of the discussion has wandered well beyond my question, but no worries there. I'm learning from it.
Thanks.
Jack
Download the Hubitat app
