Can rule machine get this complicated?

I am just spitballing here. I have a hot water heating system. The controller has an outside temp sensor, a system water temp sensor, a valve that opens and closes to regulate the temperature of the water. The controller also turns on the boiler to heat the water. There are separate safety controls in place to shutdown the boiler, for low water, high heat and such. The controller monitors the outside temperature and has two temperatures set, one being a high water temp limit and another (I think thi part is correct) that is a temp that would be the lowest of the season. So the controller regulates the water temp that circulates according to the outside temp and the set point for the coldest temp we think would happen. I have a graph of how it works and someone with math skills could I am sure come up with a formula. The controller i sgetting old and I am afraid it will crap out on me soon.. Would thi sbe something Hubitat and RM could handle? I have an arduino that I already use to control relays and monitor tempreatures. I wouldn't mind installing another to only run this operation.


Anything with safety controls I would not attempt in HE.
Honestly it seems like a little much to ask of a system like this.
If I were going to DIY it I would run this through an Arduino device for control of the device.

I would however report status, analog values, and allow basic commands through Hubitat.
But the big thing is constant device control should be done with a dedicated controller...

My opinion, there's room for debate.


The controller that is about to die, does or does not handle the safety controls.

If it does, then I'd doubly recommend a dedicated controller. You certainly don't want a fire because you upgraded the Hub right as the boiler got the water to nearly cutoff temp. Then it goes WAY over because the upgrade took two boots.

If the safety controls exist independent of your about-to-die controller, then the answer might be different. :smiley:

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The safety controls are separate from this controller. There is an over temp control, and a low water control to make sure that the boiler always has water. Just to be clear this is a hot water boiler not a steam boiler. the water never gets above 180F.

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Last summer I built my own Pool Controller. I spent more programming effort on making sure it turns off than that it turns on. I'll notice the Green water :slight_smile: But it will be a month before I notice the electricity use 24x7. There's also a heater and it too will suck massive $$ if it runs (ever.) The same watchdog monitors the heater too.

I began the project with an Arduino but pretty quickly decided it wasn't a contest to see how small I could make it. A rPi was small enough and comes with wireless (WiFi) for me to monitor it. And already has a multitasking OS :slight_smile:

Last login: Thu Feb 14 08:41:49 2019 from
raspberrypi:~ $ uptime
11:11:52 up 134 days, 17:43, 1 user, load average: 0.63, 0.52, 0.51



I have worked with rPi's in the past, I actually have one hosting a small website at my house now. I am afraid that the Pi SD card will get corrupt and I would be in the dumper.

I too have a pool that I am going to monitor the water temp and turn on a valve and a pump to run the pool water to a solar heater. That comes after the ice melts tho :))

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There are projects that will allow you to run a RPi off of a USB thumb drive or external hard drive and even SSD now.

With that said, don't skimp on the SD card. I use Samsung EVO Plus cards. One of my RPis has been running for over a year on the same card with tons of disk thrashing (it's running pi-hole, doing DNS, DDNS, and DHCP, InfluxDB and Mosquitto for my various subnets here).

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Yeah I have seen some of those projects. I went with the Arduino since in my mind a purpose built machine for doing these types of things. As I said I am just spitballing here. A new controller is over $500us Besides I want ot be able to control my house heat from my bed, car , anywhere..

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