2 zone system setup - firmware modification
Posted: Thu Oct 20, 2016 2:21 pm
[ The right title is: "Multi zone system setup (with NEST + on/off thermostat" ]
My central heating system has 2 zones:
Zone 1: main part of house with thermostat in the living room - the thermostat can open/close a electric valve towards the floor heating
Zone 2: basement area - with traditional on/off thermostat - a second thermostat can open/close a second electric valve here
Until now I used traditional on/off thermostats and some relais to ensure either one or the other thermostats force the boiler to turn on when heating was required.
I want to switch over to OpenTherm and bought a NEST as thermostat in the living room and switch off the valve for the water towards the living room (permanent open). The NEST is now directly linked to the boiler using OpenTherm (all working fine for the living room). But this means the second thermostat (on the basement) can no longer tell the boiler it needs to be turned on. Key question is: how to fix this?
My idea is the following:
- Use the OpenTherm GW between the NEST and the boiler
- Connect the valve in the living room to the first GPIO connection of the gateway (configured as output - will need some electronics to boost the signals)
- Connect the on/off switch thermostat of the basement to the other GPIO signal (configured as input)
- Modify the firmware to do the following:
* when the NEST in the living room needs heating, the signals are passed on as normal to the boiler and the gateway ensures the valve signal is turned on (GPIO pin on), so we also have warm water flowing that way. The valve will be closed when the NEST no longer requires heating (GPIO pin off)
* when the on/off thermostat in the basement needs heating, it will turn on the value there (existing cabling + relais does this already) and signals the gateway (second GPIO pin) to increase the water temperature (overriding the NEST valves)
Anybody that has done something similar?
I guess this could be done with a Domoticz script, but I rather have the logic inside a single device that is always turned on.
I think the firware changes are limited. Would this be a nice change to the firmware?
regards
Bart
My central heating system has 2 zones:
Zone 1: main part of house with thermostat in the living room - the thermostat can open/close a electric valve towards the floor heating
Zone 2: basement area - with traditional on/off thermostat - a second thermostat can open/close a second electric valve here
Until now I used traditional on/off thermostats and some relais to ensure either one or the other thermostats force the boiler to turn on when heating was required.
I want to switch over to OpenTherm and bought a NEST as thermostat in the living room and switch off the valve for the water towards the living room (permanent open). The NEST is now directly linked to the boiler using OpenTherm (all working fine for the living room). But this means the second thermostat (on the basement) can no longer tell the boiler it needs to be turned on. Key question is: how to fix this?
My idea is the following:
- Use the OpenTherm GW between the NEST and the boiler
- Connect the valve in the living room to the first GPIO connection of the gateway (configured as output - will need some electronics to boost the signals)
- Connect the on/off switch thermostat of the basement to the other GPIO signal (configured as input)
- Modify the firmware to do the following:
* when the NEST in the living room needs heating, the signals are passed on as normal to the boiler and the gateway ensures the valve signal is turned on (GPIO pin on), so we also have warm water flowing that way. The valve will be closed when the NEST no longer requires heating (GPIO pin off)
* when the on/off thermostat in the basement needs heating, it will turn on the value there (existing cabling + relais does this already) and signals the gateway (second GPIO pin) to increase the water temperature (overriding the NEST valves)
Anybody that has done something similar?
I guess this could be done with a Domoticz script, but I rather have the logic inside a single device that is always turned on.
I think the firware changes are limited. Would this be a nice change to the firmware?
regards
Bart