Floor heating automation

[wary steppe]

I have a floor heating system that uses water from the boiler to heat up rooms. It was all working with dial thermostats, so I wanted to modernize it with home assistant and zigbee thermostats
I now have all the components complete and controllable, except for the pump itself. I looked up on the internet what order of steps I should automate stuff in, but I cant find a solid answer for this.

I have the same WTH unit as in the picture, but all spots with solenoid valves
All (4) zones are controllable with ZWT198's switching on/off the valves.
The boiler can be turned on/off with the https://diyless.com/product/esp8266-thermostat-shield

If I turn on the boiler too soon after switching ZWT198's to heating, it will display a error 1 because its heating without flow (the valves need time to open up)
But im worried if the pump is gonna switch off when the floor has reached its temperature (because thats what I assume the little sensor box is for?) and that its gonna keep the boiler on (because the room takes time to heat up)

I havent made any automations yet, I prefer Node-RED for this as I have some experience in it but im unsure what the logical steps I should program would be, and should I make the pump controllable aswell or is this fine? (or maybe detect its power usage with a meter and switch off the boiler if it doesnt take any power?)
Does anyone have experience with this, thanks

[cerulean atlas]

The simplest logical steps are 1- call for heat-2 valve open-3 delay-..... Then depending on the boiler... it can either warm up to operating temps before circulating... or begin circulating right away-4 end call for heat. But with HA you can potentially make this system much smarter, because heating tons of concrete is like steering a ship, a cold floor has inertia and can take a long time to heat up and then "overshoot" the desired comfort level. With PID control the system can learn to compensate for outdoor temps, and remember the prior calls for heat, and the time the system took to respond . https://community.home-assistant.io/t/climate-smart-thermostat-with-auto-heat-cool-mode-pid-control-and-pwm/369867 Potential energy savings could be huge. Like a bathroom may only be occupied for 1 hour in the morning . The system knows that it needs to be x° at 6am so the the call for heat @ is at 5am it has 20 minutes of inertia 20 minutes of circulating and another 20 minutes of inertia after the valve closes. The one caveat is that you usually want some logic to require the boiler to prevent short cycling. With 10 zones you might not want the boiler to fire for only 1 zone..

[wary steppe]

Thank you! I read about PID and see its available in the opentherm firmware im using https://github.com/Laxilef/OTGateway
It also has equitherm, will check that out too!

So one thing I figured out is that the valves controlled were stuck, but I got them all fixed now. I also figured out the solenoid valves are closed when powered, and open when not. So yesterday I was trying to heat the whole house instead of just the office! This explains the low return temperature too I guess

Currently figuring out what thermostat controls what valve, will try to get heating itself working and will then check out PID/Equitherm. Thanks for the suggestion, savings are always welcome 🙂

[cerulean atlas]

Most valves and relay switches are either NO or NC (normaly open) or (Normally closed). A lot of them can be connectted/switched from NO to NC... or i have seen solenoid valves that the magnet can reverse polarity of the actuator. So you might have a look at yours,

[wary steppe]

Hey, thanks for the help I've been setting up some stuff 🙂
I have a question, should each room have its own PID, or should I have 1 total PID for all the rooms somehow? I only have 1 boiler, so im controlling it like this now
Seems to be working fine (heating doesnt need to be on so far)
(I turn on thermostats every morning, but block boiler from going on to cycle the valves to prevent them from getting stuck.. i should rename the subflow lol)

but the problem is that I cant optimize with boiler temperature (thats what suggested atleast), just turn it on/off since multiple rooms' PID might request different temperatures from the boiler (or should I just mathMax and set the highest request?)
https://blog.clanlaw.org.uk/pid-loop-tuning.html

[cerulean atlas]

Most importantly is your boiler capable of modulating the burner output? If not you might have to tag on the small rooms to heat when the bigger rooms require heat.I have not operated a in floor system before so I am not sure how the Inertia/response are, but you might learn how to "program" it by operating each zone manually until you understand how it responds.... Using the bedroom as an example one person might sleep better if the room is warm at bedtime, and another might like to sleep cold but have it warm in the morning. If it takes 2 hrs to warm up you either want heat 2 hrs before bedtime or wake time.. The PID helps to prevent overshooting the set point, but if you boiler cannot modulate you could end up with alot of short cycles.

[wary steppe]

I'll try to figure out if it can modulate tomorrow, but I fully expect it to since it was installed 2 months ago. Thanks again 🙂

I can set temperature for sure

[wary steppe]

It is capable of modulating
so I should probably math.max the requested temperature from the boiler, scale it from 0-1 to 0-35 (35 max temp for boiler, floor heating apparently doesnt need much more)
then hopefully end up with some nice graph like, although it looks like the boiler might be on all the time in this case..
or am I misunderstanding

[cerulean atlas]

Modulation is good, it will be less likely to short cycle. I believe the modulation is based on the return temperature... so a large cold floor will return colder than a small warm area> The Modultion may behave like a PID. As the return temp rises it can turn down the output.

[wary steppe]

I'll try figure out PID more when its actually time to turn on the heating, looks like there is a lot I can change and do so better to try out 🙂
Thanks for the help

[wary steppe]

Hi I have another question, should my boiler be set to i.e. 45c and mixing valve to 35c
or should both boiler and mixing valve be set to 35c?

[wary steppe]

Tried it out, seems to be way better 🙂 its actually reaching the temperature set on the mixing valve now (a little higher actually).
also found out the previous owner probably moved some solenoid valves around because office on, living room off.. living room floor gets warmed up 😕 renting thermal camera and opening 1 valve at a time to figure out the rooms

[cerulean atlas]

Lazer thermometer are cheap and easy to get. Might be better than the camera. plus you can use it as the season gets colder to tweak the controls, This is a link to an article of a expert answering questions about there systems, a lot of usefull info.