Tweet
Hi
I have a small evohome system, about to be extended to another 6 radiators as part of some renovations. Everything is working very well. It took a while to get used to the way it controls the boiler through TPI but it makes sense in the end.
Currently we have a Y-plan system and an old but still perfectly functional Ideal Mexico boiler. As part of the works we need to relocate the pump and three-way valve. As the valve is of uncertain age and I think it is letting by slightly I intend to take the opportunity to replace it, and possibly change the system to an S plan at the same time, with 2 2-port valves instead. The general consensus seems to be that S plan is generally a better solution in the long term.
I am also considering adding a pump overrun circuitto the system, although the boiler doesn't require it. Given the way evohome controls the boiler through regular cycling, it seems logical that running the pump for a few minutes after the boiler has switched off, whilst keeping the CH valve open would make the system more efficient by reducing the amount of heat lost through the flue and from the boiler in general (the boiler is location where this heat isn't really useful for space heating). Given the regular switching it seems that the boiler is spending more time in its 'hot and just switched off' condition than with the old fashioned room thermostat, and the overrun would be fairly easy to accomplish with a few relays.
However I then started thinking that perhaps S plan is not the best way to go here, as the CH valve will constantly be opening and closing as the system regulates the CH water temp through tpi, whereas in a Y plan the valve would remain in the CH position indefinitely (unless the HW is calling for heat at the same time). This presumably adds to wear and tear on the valve.
So my question is, given the opportunity to change from Y to S, is this a good thing or a bad thing, when used in conjunction with Evohome, and are my thoughts regarding the pump overrun correct that it would make the system more efficient? As an electrical engineer I am not scared of the level of complexity of the additional control wiring, and as we are relocating the valve(s) anyway changing the plan makes no real difference to the amount of plumbing required.
All comments welcome.
Thanks in advance
Alex
I have a small evohome system, about to be extended to another 6 radiators as part of some renovations. Everything is working very well. It took a while to get used to the way it controls the boiler through TPI but it makes sense in the end.
Currently we have a Y-plan system and an old but still perfectly functional Ideal Mexico boiler. As part of the works we need to relocate the pump and three-way valve. As the valve is of uncertain age and I think it is letting by slightly I intend to take the opportunity to replace it, and possibly change the system to an S plan at the same time, with 2 2-port valves instead. The general consensus seems to be that S plan is generally a better solution in the long term.
I am also considering adding a pump overrun circuitto the system, although the boiler doesn't require it. Given the way evohome controls the boiler through regular cycling, it seems logical that running the pump for a few minutes after the boiler has switched off, whilst keeping the CH valve open would make the system more efficient by reducing the amount of heat lost through the flue and from the boiler in general (the boiler is location where this heat isn't really useful for space heating). Given the regular switching it seems that the boiler is spending more time in its 'hot and just switched off' condition than with the old fashioned room thermostat, and the overrun would be fairly easy to accomplish with a few relays.
However I then started thinking that perhaps S plan is not the best way to go here, as the CH valve will constantly be opening and closing as the system regulates the CH water temp through tpi, whereas in a Y plan the valve would remain in the CH position indefinitely (unless the HW is calling for heat at the same time). This presumably adds to wear and tear on the valve.
So my question is, given the opportunity to change from Y to S, is this a good thing or a bad thing, when used in conjunction with Evohome, and are my thoughts regarding the pump overrun correct that it would make the system more efficient? As an electrical engineer I am not scared of the level of complexity of the additional control wiring, and as we are relocating the valve(s) anyway changing the plan makes no real difference to the amount of plumbing required.
All comments welcome.
Thanks in advance
Alex