- Messages
- 42
I know years ago before the TRV the pump went on the return, but new house to me, all TRV's on radiators except for bathroom which does not really count as that is thermo syphon, not worried about boiler as thermo syphon domestic hot water with no motorised valve, but am worried about pump, will it cavitate as the TRV's close and damage it, with pump on supply easy a by-pass valve will allow it to continue to circulate, but will a by-pass work on the return.
The system was in a mess, two pumps one for flat switched on with a thermostat, and one for main house, simply on a 13A plug, there was a time switch/programmer which said it allowed heating and DHW once or twice a day and DHW once or twice a day, plus continuous and off. However in real terms all it did was turn boiler on/off there was no connection to any pump.
The area around the boiler in the flat under the house had a flat thermostat, and a wireless receiver for another thermostat, but no thermostat linked to it.
On trying to use the system found if either pump used on it's own, it would reverse circulate water in other system, also radiators get hot on top floor with thermo syphon even when pumps switched off.
Turning off the maintenance valves on the pumps did stop the circulation, so local plumber was to fit two motorised valves, since the motorised valves have micro switches built in, easy enough to wire so unless open pump will not run.
So bought Nest Gen 3 and wired up ready for when motorised valves are fitted, also paired with 4 MiHome Energenie TRV heads in hall, dinning room and living room, at moment only using for DHW so all OK.
However two things came to mind, one is what if all TRV heads close while pump is running, and two since linked why does the TRV not show same target temperature as Nest?
As yet plumber not returned to fit valves, so if some thing needed I will not need a second supply of inhibitor, so now is the time, but most pipes hidden behind plaster board, will not only pipes, whole fuse box hidden just enough room to put hand through ceiling and turn off power.
So no option but have pumps on return, only two supplies, there are three returns, plus I assume fill pipe.
Looked at modulating pumps instead of three speed, but they need a minimum pressure, so seems can't be used on return, thought about some vac/pressure switch but would need latching and reset.
I can't be only one with pumps on return and all TRV's fitted, so how is it done? I am not doing plumbing, however I am doing wiring, all set out ready, there will be a slight problem in that if flat calls for heat without either DHW or main house calling for heat, it will not turn on boiler, just circulate water, but not worth fitting relays as flat rarely used. And also no thermostat on DHW cistern, just limit time to 1/2 hour every other day, that's enough to have hot water to wash hands in summer, shower is electric, oil only for central heating and hand wash, OK maybe odd bath, but easy enough to press boost.
So all comments welcome.
The system was in a mess, two pumps one for flat switched on with a thermostat, and one for main house, simply on a 13A plug, there was a time switch/programmer which said it allowed heating and DHW once or twice a day and DHW once or twice a day, plus continuous and off. However in real terms all it did was turn boiler on/off there was no connection to any pump.
The area around the boiler in the flat under the house had a flat thermostat, and a wireless receiver for another thermostat, but no thermostat linked to it.
On trying to use the system found if either pump used on it's own, it would reverse circulate water in other system, also radiators get hot on top floor with thermo syphon even when pumps switched off.
Turning off the maintenance valves on the pumps did stop the circulation, so local plumber was to fit two motorised valves, since the motorised valves have micro switches built in, easy enough to wire so unless open pump will not run.
So bought Nest Gen 3 and wired up ready for when motorised valves are fitted, also paired with 4 MiHome Energenie TRV heads in hall, dinning room and living room, at moment only using for DHW so all OK.
However two things came to mind, one is what if all TRV heads close while pump is running, and two since linked why does the TRV not show same target temperature as Nest?
As yet plumber not returned to fit valves, so if some thing needed I will not need a second supply of inhibitor, so now is the time, but most pipes hidden behind plaster board, will not only pipes, whole fuse box hidden just enough room to put hand through ceiling and turn off power.
So no option but have pumps on return, only two supplies, there are three returns, plus I assume fill pipe.
Looked at modulating pumps instead of three speed, but they need a minimum pressure, so seems can't be used on return, thought about some vac/pressure switch but would need latching and reset.
I can't be only one with pumps on return and all TRV's fitted, so how is it done? I am not doing plumbing, however I am doing wiring, all set out ready, there will be a slight problem in that if flat calls for heat without either DHW or main house calling for heat, it will not turn on boiler, just circulate water, but not worth fitting relays as flat rarely used. And also no thermostat on DHW cistern, just limit time to 1/2 hour every other day, that's enough to have hot water to wash hands in summer, shower is electric, oil only for central heating and hand wash, OK maybe odd bath, but easy enough to press boost.
So all comments welcome.
