jake wrote:My 'heating the house' goal is that I can heat each room in the house individually. Does the OTGW fit in that strategy?
I know I need remote controlled valves like the Danfoss + thermostats/temperature sensors in those rooms. Missing is the 'turn boiler on' configuration.
Before I knew about the OTGW, my idea was to make a relay contact at the boiler, connected to the anti-freeze connection of the boiler. Closing that contact will make the boiler think it is necessary to turn on, in order to prevent freezing of pipes and radiators in the system. This 'anti-freeze' system bypasses the open therm completely, I assume.
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I use the OTGW for this purpose, simply because I already had one. If you don't really need an OTGW you could certainly do it in the way you describe. Having said that, the OTGW is a lot of fun (gathering all kinds of data about your central heating system), and you can override the thermostat setpoint when you're away.
What I did is simply increase the thermostat setpoint in the living room when I need the boiler to start. To avoid that the living room gets too hot, you can add remote controlled valves to all your radiators there. Or, as I did it, add a central valve near the boiler that shuts off the whole living room section (including floor heating) when the temperature in that room is above the setpoint.
The downside of this approach is that you have effectively reduced your smart modulating heating system to a simple on-off system (unless only the living room needs heat). In my case, I rarely need heat when the boiler is off (only when I use the study above the garage when nobody is in the living room), so I'm fine with that restriction. If you want more intelligent control, I would advice you to look into the Honeywell EVOhome system. Expensive, but i.m.o. the best solution for the combination of individual room control, OpenTherm and Domoticz.
Whatever you choose, don't foget that your boiler should always be able to pump around hot water, even when all valves are closed. You can leave open a small radiatior, e.g. the towel radiator in the bathroom, or you can install a bypass valve.
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