was that the boiler relied solely on an internal thermostat, causing it to keep running even after the water reached the desired temperature, resulting in wasted oil. To make matters more challenging, there was no feedback from the directional valve to the boiler.
On top of that, the heating zones were not directly connected to the boiler. To get heating, I had to make sure the hot water timer coincided with the zone channel
To tackle these problems, I added a temperature sensor to the hot water tank and configured a cutoff relay using Home Assistant. Now, when the water reaches the correct temperature, Home Assistant triggers the cutoff relay, effectively shutting down the boiler. I’m convinced it paid for itself in just a week!
I’m planning to improve the heating system with Home Assistant. I want to add two more relays to each channel and keep the programmer always set to “on”. That way, I can let Home Assistant handle the heating. The cool thing is, if anything goes wrong, I can just switch back to the old system.
before I dive in, do you folks have any advice? Did I miss anything important?
I sort of envy you. My boiler has a zone controller which does all of what you’re trying to accomplish, so all I really can do with HA is monitor. Which I do. But it would be fun to build the controls from scratch. But it’s hard to justify when inexpensive, off-the-shelf components are already built and in use everywhere. Especially if I’m not around when something fails and a technician is called in to fix it.
That said, I totally agree with the design requirement that you be able to revert back to the “old way” if HA fails. My heating system has been running for something like 25 years now, and I’ve never had a version update, a bug or a breaking change.
Starting at the beginning, why is the thermostatic control for your water tank failing? That should be a very simple control circuit, and parts should be readily available if something’s broken.
But, sure, putting another relay (contactor) in line, controlled by HA, would work if the old one is stuck “on” (closed.) It would certainly be better than having the water heater controller always calling for heat.
I’m not sure what you mean by the heating loops being controlled by the hot water controls. You mentioned a timer, and I see that in the schematic, but it’s not clear where the inputs and outputs are on that. I can see why someone would want to control the water heater with a timer (in addition to a thermostat) so that it doesn’t get heat during times of when there’s little demand. It sounds like there’s something clearly wrong with the way that system is set up.
More information on the existing system might help. What types of controllers do you have on the boiler or for the zones? One circulator? Zone control valves? TRVs? A Zone controller board? Controls on the boiler itself?
Thanks Tom,
A little more info The boiler was activated through the HW channel on the timer. When the hot water tank reaches the set temperature, the bimetal thermostat at the tank’s top closes the directional motor valve on the heating coil, reducing the load on the boiler. This allows the boiler to overheat and trigger its internal thermostat to cut off. I’ve upgraded by replacing the hot water tank thermostat with a Sonoff THR3, where the relay output controls the directional motor valve. Home Assistant automation now handles boiler cutoff, resulting in what I believe is a more efficient setup.
When it comes to house heating
2 channel UFH,
1 channel down stairs UFH
2 channel up stairs UFH,
The timer only turns on the circulation pump(through the room thermostats)
So I have to ensure that the channels times are copied into the HW channel,
