TL;DR: How do I make the thermostat send a ‘heat’ request to the boiler without making the boiler use way too much gas?

Hi all,

I have a question about automating central heating. My current setup:

Ground floor:

  • Main thermostat linked to boiler (Honeywell T6 on WiFi through Honeywell integration)
  • One radiator with Sonoff TRV-ZB, zigbee
  • Three radiators with non-smart knobs that are usually open
  • The main room has a Sonoff Presence sensor

First floor:

  • Three rooms that can be occupied with Sonoff TRV-ZBs.
  • Two of three rooms have Sonoff Presence sensors

All rooms that can be heated smartly are controlled through a blueprint once shared here called ‘Advanced heating control V5’.

I have a helper called ‘Comfort Temp’ which is a slider that controls the setpoint on the main thermostat and the TRV of an occupied room.

So the obvious question is: is there any good way to get the main thermostat to send a heating request to the boiler?

I’ve seen something about a WiFi module that you can put in between the main thermostat and the boiler that offers more control (Nodo OpenTherm Gateway, OTGW). Does anyone have experience with this? Or do I solve this with more TRVs on my ground floor? I’ve heard about central heating systems not enjoying a fully thermostatic valved circuit. More TRVs also means I have to replace the valves on a couple of radiators.

Any advice would be greatly appreciated!

  • moonshadow@slrpnk.netEnglish
    1·
    14 hours ago

    In most hydronic heating systems I’ve worked on, there’s an insulated tank of hot water either somewhere in between the boiler and radiators or built into the boiler directly. The thermostats talk to valves that send the water to radiators in the rooms that need it. The boiler just keeps that water at a set temperature.

    In larger buildings with really long runs, sometimes there are valves to bypass certain radiators and/or multiple tanks located around the building. I can’t say without more information about your home, but it might make sense to have one near the area you’re trying to heat most.

    No storage tank at all and thermostats that fire up your boiler directly sounds very unusual and inefficient. The expansion tank you have is just meant to stabilize pressure, it doesn’t have enough volume to do much for temperature