Hello, I am thinking of replacing a very old gas fire with a glowworm backboiler with a multifuel stove. How would I be able to control the existing central heating pump to switch on when the water reaches a certain temperature as the old thermostat wiring on the old boiler is now redundant. The original system just just has a room stat fitted and a Landis & Gyr hot water and central heating time clock. Is there a way to make the central heating to come on when the water reached a set temprature by fitting a tank stat or something like that to the existing thermostat wiring that was connected to the old back boiler.
Multifuel stove/central heating
- Thread starter Mickyell
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Two stats wired in series one make on temp rise other break on rise.
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You're looking at a fairly major redesign here.
For starters (unless you buy one of the expensive multifuel stoves with built-in safety devices) you'll need to sort out gravity circulation to the hot water cylinder (assuming you have one)- those pipes want to be 28mm copper (no plastic) and ideally rising vertically to the cylinder.
You'll have to install metal (or non-thermosetting plastic) F & E and DHW header tanks.
You'll need a heat dump radiator again fed by gravity circulation only.
For the pump control usual setup is a thermostat on the gravity flow from the boiler and another one on the gravity return. Wire them up so that the pump only runs when temperature in BOTH pipes is above 50° C
You could use a loading valve instead.
For starters (unless you buy one of the expensive multifuel stoves with built-in safety devices) you'll need to sort out gravity circulation to the hot water cylinder (assuming you have one)- those pipes want to be 28mm copper (no plastic) and ideally rising vertically to the cylinder.
You'll have to install metal (or non-thermosetting plastic) F & E and DHW header tanks.
You'll need a heat dump radiator again fed by gravity circulation only.
For the pump control usual setup is a thermostat on the gravity flow from the boiler and another one on the gravity return. Wire them up so that the pump only runs when temperature in BOTH pipes is above 50° C
You could use a loading valve instead.
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The stove would be a dunsley Yorkshire with back boiler which has a built in thermostat that closes the air intake when it gets to a certain temperature. The stove would be connected to the existing dhw & ch pipework with 28mm flow and return up to the prismatic hot water cylinder that is directly above the stove. It's just controlling the ch pump to come on automatically before the water in the dhw cylinder gets too hot causing it to vent into the overflow pipe and then switch off when it gets to a certain lower temp on the central heating return. The timer control could be set to run all the time instead of the usual timed sequence to come on twice daily as there is no cost involved in running the set-up as have access to free dried timber except for the electric to run the pump and just turned off via the isolating switch when not needed. This is how I am wanting it to work in theory but not sure if it's feasible or do able.
In that case you need another thermostat on the cylinder set to 80°C (that's the max i use) and wired in parallel with your room stat (which will be powering the 2 thermostats on flow and return).
So, if room stat is calling for heat, power goes to F & R thermostats. Provided flow and return are both hotter than 50 then power goes to pump, rooms heated.
If cylinder gets hotter than 80 then power goes to F & R stats, provided temps are above 50 then pump runs, rooms are heated ignoring room stat.
So, if room stat is calling for heat, power goes to F & R thermostats. Provided flow and return are both hotter than 50 then power goes to pump, rooms heated.
If cylinder gets hotter than 80 then power goes to F & R stats, provided temps are above 50 then pump runs, rooms are heated ignoring room stat.
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