TRVs vs (dumb) Boilers configuration

It’s not another subject about finding the best TRV. It’s about how to configure heating circuit to make it efficient as well as provide heating to single radiators when needed.

Initially I though I can trigger the boiler’s heating by TRV. It is most common approach as I’ve seen so far on forum(s)
But friend of mine informed me that this is not efficient way. Especially because it would cause boiler starts heating more often than needed which is not good for its service live as well as inefficient energy-wise.

He says, that the best way is to have accumulated water tank with ability to maintain its temp. Such water should circulate in the system. When TRV(s) is open it causes dropping the water temperature. If temp drops under defined level the boiler starts warming water up.
In case I have no water accumulation tank, I could make my heating circuit to be such a tank. Just force water circulating, and let boiler maintain it’s temperature.

What do you think about it? Is it how you guys installed/configured it with smart TRVs?
Is it any different when using TRVs with some smart HUB which communicates with a boiler?

with regards

@maxym, did you make any progress? I’m trying to figure out my best setup for my newly bought home. Very interested how you managed to fix your setup.

Hello. No. Still waiting for someone who bring reliable answer :wink:

So what do you want to achieve? What do you have? I have a boiler and 12 radiators. I want to use Tuya TRV’s but not sure on the part in between these two. My Boiler does support OpenTherm. So maybe we can help each other?

Simmilarily to you I have about 10 radiators. House with 3 floors (incl ground one).
The main question is what to use to control Boiler based on sensors readings. And what is most efficient approach (without need of rebuilding the house).
I have Junkers boiler. I know some company (only one AFAIK) selling OpenTherm interface for that. otherwise it uses Bosh-compatible dumb circuits (maybe some Bosh communication interface is available too).
In current state I builer is driven by single themperature readings in dining-room which leads to overheating upper floors.

Right now I’m about to find the best (for me) TRV to mount before this Winter. Just to equalize temperature between floors but limmiting heating on upper ones. It could be done even without a controller.
Year ago I was thinking about Siterwell GS361A-H04 (ZigBee). Tuya whie-labels it as GTZ02. But other Tuyas (ie TS0601) offer more features, at least based on zigbee2mqtt compatibility list

@maxym, interesting. So you will only use the TRV’s to close of the heating to the top floor? But what is controlling the boiler at this moment?
If you would go for the OpenTherm solution, i found this (link). I think this could work. Did not play with it but it sounds like a solution. Not sure how to intergrade the TVR’s yet but maybe worthwhile to investigate.

Yes… generally this is my idea how to start with it. Until I gather knowledge and HW/SW to create complete and efficient solution.
Right now, having single thermostat, it causes overheating of higher-floor rooms (ie when I ventilate dining room). Closing heating on top floor will definitively help.

It will buy me the time to make proper decisions. As far as I know my boiler has own PID regulators being able to efficiently heat water depending on enviromental conditions like outside temperature. I understand that the only signal it needs is “start heating” or “stop heating”. But start heating must not result in igniting a burner. If there is enough hot water in the circuit, the boiler turns on the pump. The burner is being turned on only when temperature of incoming water from the circuit is lower than a threshold. This is how I understand it.

AFAIK my boiler has terminal with electrical inputs and outputs I can use to force heating. But I’m aware that triggering heating by single sensors/TRVs might be not efficient. And this is when I have doubts: probably there should be a central unit/controller, gathering data from all sensors and decide when to heat the water. I wouldn’t give this control to HA due to reliability (not even sure that existing addons provide efficient solutions). Also not sure if all those smart Tadoos, Nests, Honeywells aren’t just repeaters without any logic.

@maxym , nice so you are in the same position i’m in. I hope we can figure it out. I may also start with only TRV’s until i gained enough info. Regarding modulate heating i found this video which sounds like someone i would trust. I agree that it will be tricky to give the heating responsibility to HA, but i would like to give the input interface to HA. And use the DIY thermostat as the hardware.
So you are already familiar with zigbee2mqtt, what did you configure so far with this?

I’m using z2m for half a year. I would say I’m experimenting with it. Nothing serious. A few cheap door and motion sensors (Lidl) and recently dimmers from Ikea as augmentation of my Shelly based Dimmers and RGB drivers.
TBH I started with z2m as a preparation step for TRVs since I cannot believe in battery powered wifi TRVs (I know some exists though). Just to make myself familiar with this technology and components (zigbee & z2m)

Otherwise, this DIY thermostat you linked has no logic for controlling multiple TRVs hence is not able to make decisions when to heat or when not. It can however calculate boiler temperature based on current one and set point. Characteristics of PID is given and somehow not configured. Hard to judge how aggressive it is.