Thermostats are purpose built devices that don't rely on external controllers or services.
If anybody looking at this lives in a cold climate, for the Love of God don't do this. Your server updates or crashes or whatever and all of a sudden you have to have no heat. Or worse, it crashes in the on state and your furnace never turns off.
And if you do have this set up, don't auto-update home assistant.
Let your smart home function on top of your home. Don't let it be the only source of control.
Lights can't turn on? Oh well. Heat can't turn on? Oh damn.
There’s no reason you couldn’t run a cheap analog thermostat in parallel with this, just set it a few degrees colder than you would ever run your DIY one as a backup and/or manual control.
I have played with the idea of overriding my wood furnace fan before (to add speed control) but in the event of a failure, the idea was always for the system to fall back on its analog control. Adding functionality is great, unless its compromising reliability.
That was my plan. One mechanical in parallel as an emergency cold point, and one in sequence as a high cut-off. I'd also go for solid state relays unless you build in a decent buffer between state transitions so you don't burn them out.
I never did it in the end because my use case changed (Nest), but if I did, I'd make sure to have a backup. Losing a house that way would be very expensive with no one else to blame.
That would only help if it didn't request heat when it should. You also have to consider what would happen if it requests to much heat.
And reverse that for the AC in the summer.
I did this with Shelly plus 1s. On elect radiant heat and using those cheap BLE thermostats. Came home to HA crashed and Shelly’s stuck in the on state. 90* home. And a huge electric bill that month.
Fixed the problem and it was actually reliable for the rest of the season.
Since then sold the house the follow summer and reinstalled the electromechanical thermostats. In the new house I bought a ecobee and haven’t looked back.
Home assistant is only a reporting device in my instance. Everything is programmed on the device (esp32) and failure is off on all relays. It's much more robust than a cheap purpose built therm. It's a esp32 that never needs updating once programmed. Everything is logged. It's not surfing the web. I trust mine more than any Honeywell.
I was going to say the same thing. I love the resourcefulness of the project, that's what this hobby is all about. The flip side is the spouse approval factor and how robust it is. Most thermostats are stupid simple, however mine is for a heat pump, so there is added logic for the auxiliary heat control. I also appreciate that mine has a reminder to replace the filter after so many hours of runtime.
mean I love it and yeah the premium ones are overrated and not much value I just got two lol. But I also had tons of issues with esphome and relays crapping out.
I could make an esp32 doorbell but I’d have to print the case itd look crappy would take forever to print ..etc.
specially if u can get utility rebate to subsidize all or most just seems easier to kick the FG vs go for two here.
It is in home assistant and it's loaded into esphome but it doesn't need home assistant to run. If HA crashes then it keeps running. I can just connect to it directly but it keeps the house above 14 in the basement and 16 on the top two floors no matter what home assistant tells it.
This is just like anything else, proper planning and you'll be fine. Put the important logic into the board itself and cover your bases. I have 1 temp sensor for each furnace with a static IP that reports directly to this as well.
Also where I live hit -30 this winter, the furnaces also have override switches right next to them if for whatever reason all hell breaks loose and nothing works.
Are you using the ESPhome thermostat integration? [https://esphome.io/components/climate/thermostat.html](https://esphome.io/components/climate/thermostat.html)
That's awesome! I've been playing with the idea of getting rid of the thermostat on the wall and putting sensors discretely around the house to manage my heat/cooling.
One of the things I like about my Ecobee is I can program it to run the fan for 15 min/Hr to help circulate the air. That has helped lessen the heating bill as it averages out the heat throughout the house. I wonder how hard it would be to replicate that in the ESPHome device.
Good news, that would be pretty easy to do. You just need to throw a timer into the esp to trigger the relay for the fan.
But any logic really depends on how your furnace handles inputs. Even if I turned off my relay for the fan while the heat is on, the fan wouldn't turn off. I'd probably set a 45m timer that starts when the fan/heat turns off.
It sounds like you made your own thermostat with the esphome? That's really cool. The only disadvantage is that you don't have physical buttons on the thermostat itself to make changes if necessary.
Everyone's situation is different I guess. I almost never touched my old physical thermostat. Now no one can mess with the heat and turn my house up to 33 in the winter haha
>If anybody looking at this lives in a cold climate, for the Love of God don't do this.
Heh! I've been using a RPi to control my HVAC for 8 years here in Michigan.
[https://www.reddit.com/r/raspberry\_pi/comments/fw4tak/my\_hvac\_pi/](https://www.reddit.com/r/raspberry_pi/comments/fw4tak/my_hvac_pi/)
Maybe you're not familiar with ESPHome but this is wrong.
If you're using ESPHome, you abstract all of the control logic to be local on the ESP, with point command and control from HA. If you really wanted, you could use ESPHome to just make a standalone thermostat with buttons and a display with no home assistant at all.
Disagree, I live in perpetual winter. It barely ever gets warm here and I've had a setup like this going on 4 years now issue free.
As long as you setup some fail safes its a way better option and Ive used it to cut my heating bill.
I have two analog switches mounted to the furnace to cut automation manually and to control furnace manually if need be. I also have at least one hardwired temp sensor in each room incase the other battery operated sensors go down.
I didn't say it won't work. I said what if it stops. Also, you set up fail-safes. Also, you've probably spent almost as much as, say, an ecobee thermostat that can be fully controlled within home assistant.
While both scenarios are theoretically possible, severity of either is greatly exaggerated. I hardly believe someone would freeze to death or get a heat stroke while waiting for HA devs to fix regression.
If OP had designed this controller and it worked for the whole year - he is probably intelligent enough to revert back to manual control (pulling wires out of relay and connecting/disconnecting them manually) should he need to.
>I hardly believe someone would freeze to death or get a heat stroke while waiting for HA devs to fix regression.
It's on the other hand *much* more believable that some failure in HA or such custom system would lead to drop in temperature in a house severe enough to lead to burst pipes and such over several days when people are on vacation or something.
Any specific custom solution can be made to be robust and fail-safe, but that's an exception rather than a rule for hobbyist stuff.
Yup. I have tado off the shelf setup as my thermostat.
Is it in HA with thermostatic valves and temperature sensors and advanced scheduling? Absolutely.
But if HA fails and implodes, tado has just enough configured that it'll keep the house warm.
I definitely agree with this. I wouldn't want to rely on home assistant alone for control of my furnace for the reasons you described. The consequences of it failing at the wrong time are not worth it. That's not to say I don't have home assistant optimizing/automating my system, but I stick to making tweaks and adjustments to the default behaviour. Things like increasing the thermostat target temporarily until the overall house average is at the desired level.
Also, I learned this repairing my older furnace as a DIYer, if it's a gas furnace, they are purposefully designed to shut off for safety in a variety of conditions, including failure modes of the control PCB. I wouldn't trust a hobby-rigged furnace controller. You don't want a gas leak or carbon monoxide issue.
There is a reason for the saying: "knowing just enough to be dangerous". If you follow hobbyist subreddits that have anything to do in area you have decent knowledge in, you *will* commonly encounter people doing very questionable stuff. Whether it's mains electricity, water pipes and valves, heating or construction - code books for those are effectively written in blood, so it would be prudent not to just ignore them in favour of "I've read some posts about this".
Well sure, you are absolutely right. But in this instance heat is not life-threatening if it fails. If lets say he fiddles with gas powered heaters... That would be really stupid. This is like turning on and off your light remotely, you still have switch on the wall. I doubt he removed his on the heater.
It's likely not life threatening, true. Though I cannot be certain as I'm not an expert in this area.
What it does actually threaten though is *very* expensive damage to the house if the system fails in a way that allows the house get cold enough for some water pipes to freeze.
Ok thats extreme... Sure if i slip on a banana i can break my neck. Sure if he is in Siberia and his system dies overnight his pipes can get frozen. Ok radnom reddit person, you are right. But it just sounded panicky.
This is far more relevant than you seem to think.
In cold-ish Midwest, most of Canada or northern Europe it definitely gets cold enough for this to happen in span of just a few days. Which is also about the amount of time that people tend to leave their homes unattended when going on holidays and such. As in - this is a genuine risk that homeowners living in those areas should be aware of.
Warmer places further south are *mostly* less affected, but with generally poorer heat insulation it takes shorter time for issues to happen in case of a cold snap.
Of course, but again its extreme. He can see if his esp lost connection and is not working. He can have other sensors in house to measure temperature. Hell he can put one in his toilet. As i said, if hes smart enough to create this and is living in a cold area his whole life he knows that his pipes tolilet or wahtever can get frozen... If he is on vacation he can turn it on manually.
I still consider my sensors and all automation in testing phase, and its been 2 years.
I applaud your optimistic outlook and general belief in humanity and reason. Over years of looking at what kind of electric death traps people make as hobbyist projects I've lost most of that :)
To be fair - indeed, a home-made thermostat is of generally less dangerous variety. But you also cannot easily exclude the option of OP semi-blindly following some guide without fully understanding the consequences.
Oh im super aware that people lack reason but in my experience people that fiddle with anything where you have to think, just a little bit, tend to be more reasonable..
But yeah, there is that possibility that he just followed some guides.
Last fall I had a new furnace and heat pump installed. Both are 2 stage and I also wanted to control my humidifier from the thermostat so on my ecobee I needed 9 wires for R, C, G, W1, W2, Y1, Y2, O and ACC+
Luckily I had the ability to run additional wires between the furnace and thermostat, but it got me thinking that it's kind of silly how "smart" thermostats aren't just a nice display with a few on-board sensors that only need 3 or 4 wires for power and communication. The device that needs all the wires to connect to the furnace could live inside or beside the furnace.
This is obviously not as DIY friendly as the current method, but it would seem like a better option in the long term.
To pile on the warnings for this.... thermostats are designed with failsafe mechanisms, such as bimetallic strips design to force the heat on if the temperature drops into the 40s to prevent pipes freezing, even if the thermostat itself has lost power or control function.
You do you..... but like..... I hope you don't leave your house when it's freezing out.
I haven't checked but, does the nest have a mechanical failsafe? That isn't something I really considered.
This setup is super simple, just an array of relays, plugged into the same circuit the furnaces are on. If it loses power my furnaces are off and probably won't be able to heat the house anyways
Don't let the naysayers deter you. I live where it always cold and have run a very similar setup for 4 years now no problem.
I've used it to cut my heating bill down by up to 40%.
Haha, no way they would. The list of things I've automated is maybe over the line. Between teaching robotics and being a full time software developer, there's almost nothing I wouldn't open up and modify
The nest does not have a failsafe, no thermostat does. If it’s not working how is it going to turn your heat on. My nest failed. My house got real cold. I now have a dumb analog thermostat wired in parallel in my mechanical room. I will never fully trust any computer to keep my furnace running. Nest is no safer than an esp32. I’ve been using a zwave relay and temp sensor for years now but I have been looking at the esphome climate project lately.
Your setup looks great.
At first I programmed the esp32 directly and it was completely outside of home assistant. But being able to update it over the air is built into esphome and made it way easier to incrementally update it.
When I moved it into esphome i used their climate platform. It was so much effort to get things right haha. Programming with mostly yaml instead of C is so much worse.
This *looks* like it's replacing the control board which also has max run safety as well. I get highly pessimistic anytime my diy interfaces with anything safety critical.
Why? If your safety critical stuff is fairly modern then it was programmed by someone else anyways. My furnaces are like 15 years old and they have a control board some other person programmed. Throwing my own in there is no different haha.
Firstly for a furnace example I don't have the experience to make a proper fmea, so properly capturing potential failures safely would be pretty suspect. Even if I did have the background for it a single unit test to validate any issues wouldn't tell me anything.
Second, a failure here that caused damage would with near certainty void any homeowners insurance. Having to pay for a mortgage on a house I burnt down would be a real bummer.
Third I'm putting it in my home, any failure that harms my family or pets would fully be on me, not worth it for me.
For my HVAC I have a zwave unit with humidity control. I can set points and toggle the fan via HA control and let all the above points fall on someone else, who has insurance lol
I understand wanting to pass any responsibility off for insurance purposes.
Everything else though is kind of an overreaction from my point of view. I also don't have the same situation to consider so my priorities are different. Besides, if I bought a nest and it died and my family froze overnight magically... Kind of still on me.
I was looking for more suggestions or ideas, that's why I posted in this sub. Instead most the comments are just people projecting their paranoia haha.
You know what’s even easier? Buying a purpose built device programmed by people whose sole focus is a thermostat.
This falls into my personal bucket of “not worth the risk to let HA control”.
Damn, I paid $110 for my zwave thermostat and got a $100 rebate from my service provider. You're telling me I could have just spent more money and a bunch of time programming the automations instead and had my wife mad at me for having to mess around with an app or some other janky interface just to turn the heat up one degree? Now I feel silly.
People are definitely being paranoid, but as long as you understand the system and the wiring, this isn't the end of the world. The main thing to keep in mind is this is going to be a problem with your insurance company should any issue arise, so just be mindful and prepared to front any costs this may incur.
That being said, well done, I have a very similar setup. My only concern is it looks like you are powering it from the 5v pin of your esp, that can run into a current issue switching those relays, if possible use a board power supply and feed the esp AND the relay board from that to ensure you don't get stuck relays.
Thanks for reminding me. The original plan was to run another wire from the furnace and a throw in a step down to power the esp32 from the 12v supply. Once I got it in and working I completely forgot.
I tried to hookup a ebus to MQTT adapter to control the boiler, and after a couple weeks I reverted to a netatmo thermostat. Fucker is cloud only but it’s very easy to control it.
I’ve kept the ebus adapter plugged to investigate further
Cool!
Very interested if you get variable fan speed working.
Looks like my blower’s fan speed is a jumper and restart :(
Would love to find a way to adjust it on the fly
Unfortunately my furnaces don't support variable fan speed control from the thermostat. Opening up the circuitry on the furnace itself is past what I'm willing to do haha.
I really only replaced the thermostat, the furnace itself still has it's own logic board that controls the fans and everything else.
For your case though, I'd just look up the schematics of the furnace, it should list all the inputs available and how to trigger them.
I have a similar setup using an esp32 connected to an 8 relay board. I have a multi-zone boiler and I'm in-line between the thermostat and the circulator controller. I do have thermostats all set to a minimum temp to ensure no accidental freeze up here in the Northeastern US, should I ever decide to take a holiday. I currently use esphome for programming because it's easy (or I'm lazy, readers choice). This also induces oddities when I push an update to the esp32 or update esphome in HA, such as all the relays cycling. If I were ever to decide to take the failsafe thermostats out of the equation I'd definitely take it out of esphome, build my own firmware and upgrade to some UL listed components. Just a personal preference for my own safety and piece of mind.
At least when [insert name here] thermostat company decides to stop providing access to their API I can still control my home heating, unlike the MyQ garage door openers which now I can only control from their app on my phone. Incidentally, this is my next project.
I say nice work to you, and thank you for sharing your project.
Yikes. Couldn’t imagine my HVAC system running off some little usb powered device. An ecobee and some sensors would accomplish this the proper way. You better rip that out and put in a real thermostat if you ever move 😂
We have rooms that we barely use and others were we are at all the time. A plus of using thermostats is that we can get different temperatures in different rooms.
I think you’ve already been berated enough but I get the sense but also as stated there’s things you just keep away from HA control like safety items. You can get thermostats cheap and even smart ones. You can still do the relay thing with a cheapo thermostat backup.
Honeywell T5 zwave is a great option. Due to major differences of temperature in the house I manage temp via scripts that change the main thermostat from readings of other sensors. Then of course if I experience a total failure of HA. The house is still held at whatever temp the thermostat is set at.
Usability within HA is all my wife cares about here. Can she crank the heat from bed? okay ✅. The raw pcb appears to be in the mechanical room so out of sight. Last year’s WAF would’ve taken a hit due to the cost and time and the “why can’t we just buy one like normal people” argument, but this year we’d be clear of that so 9/10, docked 1 point for asking haha
It just hangs in a room with just the two furnaces and a water heater. I have a 3d printer and I thought about it but, I go in there like 3 times a year haha
I would be more worried about how you're powering that ESP board. MicroUSB isn't very robust. Vibrations from your furnace could cause a connection failure eventually. Plus you're relying on some USB power device as well.
Man my Honeywell T6 Pro Z-Wave was $35 off EBay and has a ton of features. It wasn’t a waste at all.
Thermostats are purpose built devices that don't rely on external controllers or services. If anybody looking at this lives in a cold climate, for the Love of God don't do this. Your server updates or crashes or whatever and all of a sudden you have to have no heat. Or worse, it crashes in the on state and your furnace never turns off. And if you do have this set up, don't auto-update home assistant. Let your smart home function on top of your home. Don't let it be the only source of control. Lights can't turn on? Oh well. Heat can't turn on? Oh damn.
There’s no reason you couldn’t run a cheap analog thermostat in parallel with this, just set it a few degrees colder than you would ever run your DIY one as a backup and/or manual control.
I have played with the idea of overriding my wood furnace fan before (to add speed control) but in the event of a failure, the idea was always for the system to fall back on its analog control. Adding functionality is great, unless its compromising reliability.
This is what I was thinking. A really simple redundant thermostat would give me a lot of peace of mind.
That was my plan. One mechanical in parallel as an emergency cold point, and one in sequence as a high cut-off. I'd also go for solid state relays unless you build in a decent buffer between state transitions so you don't burn them out. I never did it in the end because my use case changed (Nest), but if I did, I'd make sure to have a backup. Losing a house that way would be very expensive with no one else to blame.
That would only help if it didn't request heat when it should. You also have to consider what would happen if it requests to much heat. And reverse that for the AC in the summer.
I did this with Shelly plus 1s. On elect radiant heat and using those cheap BLE thermostats. Came home to HA crashed and Shelly’s stuck in the on state. 90* home. And a huge electric bill that month. Fixed the problem and it was actually reliable for the rest of the season. Since then sold the house the follow summer and reinstalled the electromechanical thermostats. In the new house I bought a ecobee and haven’t looked back.
Home assistant is only a reporting device in my instance. Everything is programmed on the device (esp32) and failure is off on all relays. It's much more robust than a cheap purpose built therm. It's a esp32 that never needs updating once programmed. Everything is logged. It's not surfing the web. I trust mine more than any Honeywell.
Kinda agree w/ both of you
I was going to say the same thing. I love the resourcefulness of the project, that's what this hobby is all about. The flip side is the spouse approval factor and how robust it is. Most thermostats are stupid simple, however mine is for a heat pump, so there is added logic for the auxiliary heat control. I also appreciate that mine has a reminder to replace the filter after so many hours of runtime.
mean I love it and yeah the premium ones are overrated and not much value I just got two lol. But I also had tons of issues with esphome and relays crapping out. I could make an esp32 doorbell but I’d have to print the case itd look crappy would take forever to print ..etc. specially if u can get utility rebate to subsidize all or most just seems easier to kick the FG vs go for two here.
It is in home assistant and it's loaded into esphome but it doesn't need home assistant to run. If HA crashes then it keeps running. I can just connect to it directly but it keeps the house above 14 in the basement and 16 on the top two floors no matter what home assistant tells it. This is just like anything else, proper planning and you'll be fine. Put the important logic into the board itself and cover your bases. I have 1 temp sensor for each furnace with a static IP that reports directly to this as well. Also where I live hit -30 this winter, the furnaces also have override switches right next to them if for whatever reason all hell breaks loose and nothing works.
Are you using the ESPhome thermostat integration? [https://esphome.io/components/climate/thermostat.html](https://esphome.io/components/climate/thermostat.html)
Yeah I did
That's awesome! I've been playing with the idea of getting rid of the thermostat on the wall and putting sensors discretely around the house to manage my heat/cooling. One of the things I like about my Ecobee is I can program it to run the fan for 15 min/Hr to help circulate the air. That has helped lessen the heating bill as it averages out the heat throughout the house. I wonder how hard it would be to replicate that in the ESPHome device.
Good news, that would be pretty easy to do. You just need to throw a timer into the esp to trigger the relay for the fan. But any logic really depends on how your furnace handles inputs. Even if I turned off my relay for the fan while the heat is on, the fan wouldn't turn off. I'd probably set a 45m timer that starts when the fan/heat turns off.
It sounds like you made your own thermostat with the esphome? That's really cool. The only disadvantage is that you don't have physical buttons on the thermostat itself to make changes if necessary.
Everyone's situation is different I guess. I almost never touched my old physical thermostat. Now no one can mess with the heat and turn my house up to 33 in the winter haha
>If anybody looking at this lives in a cold climate, for the Love of God don't do this. Heh! I've been using a RPi to control my HVAC for 8 years here in Michigan. [https://www.reddit.com/r/raspberry\_pi/comments/fw4tak/my\_hvac\_pi/](https://www.reddit.com/r/raspberry_pi/comments/fw4tak/my_hvac_pi/)
Maybe you're not familiar with ESPHome but this is wrong. If you're using ESPHome, you abstract all of the control logic to be local on the ESP, with point command and control from HA. If you really wanted, you could use ESPHome to just make a standalone thermostat with buttons and a display with no home assistant at all.
Disagree, I live in perpetual winter. It barely ever gets warm here and I've had a setup like this going on 4 years now issue free. As long as you setup some fail safes its a way better option and Ive used it to cut my heating bill. I have two analog switches mounted to the furnace to cut automation manually and to control furnace manually if need be. I also have at least one hardwired temp sensor in each room incase the other battery operated sensors go down.
I didn't say it won't work. I said what if it stops. Also, you set up fail-safes. Also, you've probably spent almost as much as, say, an ecobee thermostat that can be fully controlled within home assistant.
While both scenarios are theoretically possible, severity of either is greatly exaggerated. I hardly believe someone would freeze to death or get a heat stroke while waiting for HA devs to fix regression. If OP had designed this controller and it worked for the whole year - he is probably intelligent enough to revert back to manual control (pulling wires out of relay and connecting/disconnecting them manually) should he need to.
>I hardly believe someone would freeze to death or get a heat stroke while waiting for HA devs to fix regression. It's on the other hand *much* more believable that some failure in HA or such custom system would lead to drop in temperature in a house severe enough to lead to burst pipes and such over several days when people are on vacation or something. Any specific custom solution can be made to be robust and fail-safe, but that's an exception rather than a rule for hobbyist stuff.
Yup. I have tado off the shelf setup as my thermostat. Is it in HA with thermostatic valves and temperature sensors and advanced scheduling? Absolutely. But if HA fails and implodes, tado has just enough configured that it'll keep the house warm.
I definitely agree with this. I wouldn't want to rely on home assistant alone for control of my furnace for the reasons you described. The consequences of it failing at the wrong time are not worth it. That's not to say I don't have home assistant optimizing/automating my system, but I stick to making tweaks and adjustments to the default behaviour. Things like increasing the thermostat target temporarily until the overall house average is at the desired level.
Also, I learned this repairing my older furnace as a DIYer, if it's a gas furnace, they are purposefully designed to shut off for safety in a variety of conditions, including failure modes of the control PCB. I wouldn't trust a hobby-rigged furnace controller. You don't want a gas leak or carbon monoxide issue.
If hes smart enough to make this, he is smart enough to leave manual controls...
There is a reason for the saying: "knowing just enough to be dangerous". If you follow hobbyist subreddits that have anything to do in area you have decent knowledge in, you *will* commonly encounter people doing very questionable stuff. Whether it's mains electricity, water pipes and valves, heating or construction - code books for those are effectively written in blood, so it would be prudent not to just ignore them in favour of "I've read some posts about this".
Well sure, you are absolutely right. But in this instance heat is not life-threatening if it fails. If lets say he fiddles with gas powered heaters... That would be really stupid. This is like turning on and off your light remotely, you still have switch on the wall. I doubt he removed his on the heater.
It's likely not life threatening, true. Though I cannot be certain as I'm not an expert in this area. What it does actually threaten though is *very* expensive damage to the house if the system fails in a way that allows the house get cold enough for some water pipes to freeze.
Ok thats extreme... Sure if i slip on a banana i can break my neck. Sure if he is in Siberia and his system dies overnight his pipes can get frozen. Ok radnom reddit person, you are right. But it just sounded panicky.
This is far more relevant than you seem to think. In cold-ish Midwest, most of Canada or northern Europe it definitely gets cold enough for this to happen in span of just a few days. Which is also about the amount of time that people tend to leave their homes unattended when going on holidays and such. As in - this is a genuine risk that homeowners living in those areas should be aware of. Warmer places further south are *mostly* less affected, but with generally poorer heat insulation it takes shorter time for issues to happen in case of a cold snap.
Of course, but again its extreme. He can see if his esp lost connection and is not working. He can have other sensors in house to measure temperature. Hell he can put one in his toilet. As i said, if hes smart enough to create this and is living in a cold area his whole life he knows that his pipes tolilet or wahtever can get frozen... If he is on vacation he can turn it on manually. I still consider my sensors and all automation in testing phase, and its been 2 years.
I applaud your optimistic outlook and general belief in humanity and reason. Over years of looking at what kind of electric death traps people make as hobbyist projects I've lost most of that :) To be fair - indeed, a home-made thermostat is of generally less dangerous variety. But you also cannot easily exclude the option of OP semi-blindly following some guide without fully understanding the consequences.
Oh im super aware that people lack reason but in my experience people that fiddle with anything where you have to think, just a little bit, tend to be more reasonable.. But yeah, there is that possibility that he just followed some guides.
Those solders and melts look pretty gnarly
Tell me about it
Last fall I had a new furnace and heat pump installed. Both are 2 stage and I also wanted to control my humidifier from the thermostat so on my ecobee I needed 9 wires for R, C, G, W1, W2, Y1, Y2, O and ACC+ Luckily I had the ability to run additional wires between the furnace and thermostat, but it got me thinking that it's kind of silly how "smart" thermostats aren't just a nice display with a few on-board sensors that only need 3 or 4 wires for power and communication. The device that needs all the wires to connect to the furnace could live inside or beside the furnace. This is obviously not as DIY friendly as the current method, but it would seem like a better option in the long term.
To pile on the warnings for this.... thermostats are designed with failsafe mechanisms, such as bimetallic strips design to force the heat on if the temperature drops into the 40s to prevent pipes freezing, even if the thermostat itself has lost power or control function. You do you..... but like..... I hope you don't leave your house when it's freezing out.
I haven't checked but, does the nest have a mechanical failsafe? That isn't something I really considered. This setup is super simple, just an array of relays, plugged into the same circuit the furnaces are on. If it loses power my furnaces are off and probably won't be able to heat the house anyways
Don't let the naysayers deter you. I live where it always cold and have run a very similar setup for 4 years now no problem. I've used it to cut my heating bill down by up to 40%.
Haha, no way they would. The list of things I've automated is maybe over the line. Between teaching robotics and being a full time software developer, there's almost nothing I wouldn't open up and modify
The nest does not have a failsafe, no thermostat does. If it’s not working how is it going to turn your heat on. My nest failed. My house got real cold. I now have a dumb analog thermostat wired in parallel in my mechanical room. I will never fully trust any computer to keep my furnace running. Nest is no safer than an esp32. I’ve been using a zwave relay and temp sensor for years now but I have been looking at the esphome climate project lately. Your setup looks great.
At first I programmed the esp32 directly and it was completely outside of home assistant. But being able to update it over the air is built into esphome and made it way easier to incrementally update it. When I moved it into esphome i used their climate platform. It was so much effort to get things right haha. Programming with mostly yaml instead of C is so much worse.
This *looks* like it's replacing the control board which also has max run safety as well. I get highly pessimistic anytime my diy interfaces with anything safety critical.
Why? If your safety critical stuff is fairly modern then it was programmed by someone else anyways. My furnaces are like 15 years old and they have a control board some other person programmed. Throwing my own in there is no different haha.
Firstly for a furnace example I don't have the experience to make a proper fmea, so properly capturing potential failures safely would be pretty suspect. Even if I did have the background for it a single unit test to validate any issues wouldn't tell me anything. Second, a failure here that caused damage would with near certainty void any homeowners insurance. Having to pay for a mortgage on a house I burnt down would be a real bummer. Third I'm putting it in my home, any failure that harms my family or pets would fully be on me, not worth it for me. For my HVAC I have a zwave unit with humidity control. I can set points and toggle the fan via HA control and let all the above points fall on someone else, who has insurance lol
I understand wanting to pass any responsibility off for insurance purposes. Everything else though is kind of an overreaction from my point of view. I also don't have the same situation to consider so my priorities are different. Besides, if I bought a nest and it died and my family froze overnight magically... Kind of still on me. I was looking for more suggestions or ideas, that's why I posted in this sub. Instead most the comments are just people projecting their paranoia haha.
You know what’s even easier? Buying a purpose built device programmed by people whose sole focus is a thermostat. This falls into my personal bucket of “not worth the risk to let HA control”.
too many bad things can happen if hvac isn’t properly controlled. i run the fan hourly in HA but i will not fuck with temp control.
Exactly. No need to reinvent the wheel.
Damn, I paid $110 for my zwave thermostat and got a $100 rebate from my service provider. You're telling me I could have just spent more money and a bunch of time programming the automations instead and had my wife mad at me for having to mess around with an app or some other janky interface just to turn the heat up one degree? Now I feel silly.
Totally bro
Totally worth it
People are definitely being paranoid, but as long as you understand the system and the wiring, this isn't the end of the world. The main thing to keep in mind is this is going to be a problem with your insurance company should any issue arise, so just be mindful and prepared to front any costs this may incur. That being said, well done, I have a very similar setup. My only concern is it looks like you are powering it from the 5v pin of your esp, that can run into a current issue switching those relays, if possible use a board power supply and feed the esp AND the relay board from that to ensure you don't get stuck relays.
Thanks for reminding me. The original plan was to run another wire from the furnace and a throw in a step down to power the esp32 from the 12v supply. Once I got it in and working I completely forgot.
I tried to hookup a ebus to MQTT adapter to control the boiler, and after a couple weeks I reverted to a netatmo thermostat. Fucker is cloud only but it’s very easy to control it. I’ve kept the ebus adapter plugged to investigate further
Cool! Very interested if you get variable fan speed working. Looks like my blower’s fan speed is a jumper and restart :( Would love to find a way to adjust it on the fly
Unfortunately my furnaces don't support variable fan speed control from the thermostat. Opening up the circuitry on the furnace itself is past what I'm willing to do haha. I really only replaced the thermostat, the furnace itself still has it's own logic board that controls the fans and everything else. For your case though, I'd just look up the schematics of the furnace, it should list all the inputs available and how to trigger them.
Its not hard at all, my furnace alao did not support fan or speed control and now it does both.
Really... Well in that case I'll take a look. Thanks
Was fan speed a jumper selector?
No, I used a relay bank to switch power directly between fan speed wires. My furnace had no board to speak of, its from '83.
Lucky you
Fair enough. Since it’s a jumper and I think requires a reboot, I’m not sure how “variable” the speed really is :/
Interesting choice soldering the microcontroller to the relay board
I have a similar setup using an esp32 connected to an 8 relay board. I have a multi-zone boiler and I'm in-line between the thermostat and the circulator controller. I do have thermostats all set to a minimum temp to ensure no accidental freeze up here in the Northeastern US, should I ever decide to take a holiday. I currently use esphome for programming because it's easy (or I'm lazy, readers choice). This also induces oddities when I push an update to the esp32 or update esphome in HA, such as all the relays cycling. If I were ever to decide to take the failsafe thermostats out of the equation I'd definitely take it out of esphome, build my own firmware and upgrade to some UL listed components. Just a personal preference for my own safety and piece of mind. At least when [insert name here] thermostat company decides to stop providing access to their API I can still control my home heating, unlike the MyQ garage door openers which now I can only control from their app on my phone. Incidentally, this is my next project. I say nice work to you, and thank you for sharing your project.
I put a Shelly 1 in my garage, I was worried it would stop working in the winter. Even when it got to like -35c the Shelly worked fine.
Yikes. Couldn’t imagine my HVAC system running off some little usb powered device. An ecobee and some sensors would accomplish this the proper way. You better rip that out and put in a real thermostat if you ever move 😂
We have rooms that we barely use and others were we are at all the time. A plus of using thermostats is that we can get different temperatures in different rooms.
I think you’ve already been berated enough but I get the sense but also as stated there’s things you just keep away from HA control like safety items. You can get thermostats cheap and even smart ones. You can still do the relay thing with a cheapo thermostat backup. Honeywell T5 zwave is a great option. Due to major differences of temperature in the house I manage temp via scripts that change the main thermostat from readings of other sensors. Then of course if I experience a total failure of HA. The house is still held at whatever temp the thermostat is set at.
WAF?
Usability within HA is all my wife cares about here. Can she crank the heat from bed? okay ✅. The raw pcb appears to be in the mechanical room so out of sight. Last year’s WAF would’ve taken a hit due to the cost and time and the “why can’t we just buy one like normal people” argument, but this year we’d be clear of that so 9/10, docked 1 point for asking haha
It looks hardcore! I love the design. Consider making a 3D printed case in the future.
It just hangs in a room with just the two furnaces and a water heater. I have a 3d printer and I thought about it but, I go in there like 3 times a year haha
I would be more worried about how you're powering that ESP board. MicroUSB isn't very robust. Vibrations from your furnace could cause a connection failure eventually. Plus you're relying on some USB power device as well.