Yes, I’ve got that, but I mean more like what’s the recommended location and launch/relaunch method for my data collection scripts for the least painful updates in future? Are there ways that the usual upgrades are unlikely to break?
Yes, I saw that post. I think you’re correct to view Thermostatic Radiator Valves as basically an upper limit on what that room will take from the heating loop. That’s my first task for a controllable TRV, to turn down heating in a room at times when no-one is in it, but ideally with some pushbutton to start heating it as soon as we know someone wants it, even if we’re not home, before they start their journey (in part because our low-temperature radiators don’t heat rooms quickly and I don’t want to use the old heater if we can avoid it). Expect some questions from me on a post about smart/remote TRVs some time soon!
I also don’t understand why some TRVs say they won’t work with heat pumps, unless maybe some don’t work well with low-temperature radiators and need the old 60-70 degree heating loops.
Why is your system working so well? As I understand it, your control program does “feels like” weather compensation with some extra logic to reduce cycling and avoid pumping water when it’s not being heated, so I think you’ve effectively implemented a curve that matches your heat loss and desired target temperature. And one of your tweaks is to stop heating when the radiators aren’t losing enough heat, which I think would happen when all rooms are close to that curve’s target value, effectively using the heating loop as a whole-house thermostat! If one room is disproportionately cold, I think its TRV would be more open so it would take heated water more quickly than the others and lose enough heat to keep the pump running, and eventually bring that room back up and balance the system again, allowing the return temperature to get close to the flow and stop.
How good is your program at recovering from events like someone foolish switching the heating off in error for a few hours in winter? Using the Mitsubishi controller’s curve settings, I have at least once lost control of the house temperature so it wasn’t coming back on its own any time soon. I brute-forced a recovery by switching to flow temperature mode and setting a fairly high flow temperature until analogue thermometers around the house all read OK. Then I set a new curve using the learning (new values and a bigger bend to account for how exposed to the wind we are), switched back to curve mode, rinsed and repeated.
I suspect your control logic would do better than Mitsubishi’s because it could factor in other sensors and take more extreme actions. The Mitsubishi’s curve mode seems to be reacting to the outdoor sensor alone, pays no attention to the room thermometer and does not react much to the flow-return difference: as far as I can tell, it stops heating if the flow-return difference gets small, but it still runs the pump most of the time and it never reacts to a large flow-return gap by increasing the flow temperature temporarily.
I hope that you will permit me to slightly drift into two other quirks that I found while experimenting with our ecodan about which I’d like to ask for other experiences:
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It seems that our ecodan always heats water up to the set temperature every time hot water comes out of a “prohibit” timer phase, even if the tank sensor temperature is within than the allowed drop. Is this normal? Do others? I currently exploit this to heat most of our water with cheaper overnight electricity (by having a prohibit ending at something like 4am) but it is generally a bit annoying because there are times of the day/week when I’d like not to heat water unless it’s really really needed, without always reheating the tank at the end of such a period. I guess I could use pymelcloud to turn the tank set temperature down and up on a schedule but that may be a bad idea for some reason I’m not thinking of, or, even more intrusively, have no schedule and use pymelcloud to press the virtual “Heat Now” button if a mix of time and tank temperature sensor conditions are met.
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Does the Mitsubishi’s room thermostat mode heat the radiators to higher flow temperatures but more intermittently, for shorter times in total? Is that how it is expected to work? That seemed to combine with our windswept location to deliver a poor CoP (closer to 3 than 4) and higher bills in early November (and 6-9°C out so not that cold) and motivated me to start reading and then experimenting.
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