3 ms·
I had an old boiler that would sometimes trip and lock out the heat until someone went down and power cycled it. (It was its own monstrous hack of a gas burner
by sokoloff 3y ago
I had an old boiler that would sometimes trip and lock out the heat until someone went down and power cycled it. (It was its own monstrous hack of a gas burner fitted to a 1950s oil boiler and I think a flame proving sensor was bad.)
Every time it happened, it made for a long heat up cycle to warm the water and rads and eventually the house.
So I built an Arduino controlled NC relay that removed power for 1 minute out of every 120. That was often enough to eliminate the effect of the fault, but not so often that I had concerns about filling too much gas if the boiler ever failed to ignite. 12 failed ignitions per day wouldn’t give a build up to be worried about.
That ~20 lines of code kept it working for several years until the boiler was replaced.
- progbits 3y agoI have a similar one. Our boiler has a pump to cycle hot water around the house - this makes it so you get warm water right away when you turn on a faucet and also prevents pipes in exterior walls from freezing in the winter. This stopped working, the pump is fine but the boiler was no longer triggering it. I just wired up mains through an esp32 relay board to the pump and configured a regular timer via esphome. Temperature based logic would be even better but I didn't find a good way to measure pipe temperature yet.
- myself248 3y agoI'm thiiiiiiis close to installing a circulating pump. I plan to power it off the bathroom lightswitch, which I might just replace with a motion sensor.
- sokoloff 3y agoI eventually switched to an ESP32 and added temperature graphing: https://imgur.com/a/VM7nD74 https://imgur.com/a/VM7nD74 IIRC, I used an RTD that I had left over from a 3D printer upgrade, but an 18B20 would fine as well. A 10K NTC resistor might even be good enough. For what I needed (and I think for what you need), just fixing the sensor to the outside of the pipe [if metal] will give you a usable signal. That sensor was just metal HVAC taped to the front cast iron door of the burner chamber. But a dead-simple timer solution gets you pretty far as you know.
- progbits 3y agoThe pipes are insulated and I didn't want to cut into that, but maybe a small hole for a sensor wouldn't be too bad. But as you say, timer works good enough and that means little motivation to continue to work on it -- countless other projects await :) BTW I've also tuned the timer to run for longer in the morning to get a hot shower ready. Edit: nice dashboard, what are you using for the chart? I like the vintage look.
- sokoloff 3y agoThat is another somewhat hacky thing. I have a mix of shame and pride that the chart (everything in the rectangle) is entirely hand-coded SVG elements emitted by the ESP web request handler.
- smallpipe 3y agoCouldn’t that be achieved with a mechanical timer switch and zero lines of code ?
- yjftsjthsd-h 3y agoProbably that doesn't give you small enough time increments