Thinking of adding the hot water kit to my Evohome

[top brake]

I am curious what the hot water overrun parameter is for? It isn't a boiler overrun because the controller can't independently cut heat but keep the pump running with the wiring it has.....so not sure what that is for.

Hot water overrun
Specifies how long the valve for the hot water is open or the hot water pump is running to extract all the heat to avoid blocking the heat source.

Needs to be Figure 4 installation 'hot water single valve' with boiler relay for this to work

[jonstatt]

Hot water overrun
Specifies how long the valve for the hot water is open or the hot water pump is running to extract all the heat to avoid blocking the heat source.

Needs to be Figure 4 installation 'hot water single valve' with boiler relay for this to work

Ah! That makes sense then. Thanks

[top brake]

Ah! That makes sense then. Thanks

No problem

as has been recommended by evohome shop and others Fig 4 is the optimal way to install.

S Plan or Y Plan is more of an easy retrofit with minimal wiring changes and has some compromises.

[jonstatt]

No problem

as has been recommended by evohome shop and others Fig 4 is the optimal way to install.

S Plan or Y Plan is more of an easy retrofit with minimal wiring changes and has some compromises.

Yes I did see several say that Fig 4 was the best way and I may change to that at some point. THe reason I was concerned about it was because it means when heating hot water, you are also heating the entire heating loop. Even if all radiators are closed, in a 4 bedroom town house, that is still a lot of pipe work you are circulating water around and trying to heat up. Am I missing something about this?

[top brake]

Yes I did see several say that Fig 4 was the best way and I may change to that at some point. THe reason I was concerned about it was because it means when heating hot water, you are also heating the entire heating loop. Even if all radiators are closed, in a 4 bedroom town house, that is still a lot of pipe work you are circulating water around and trying to heat up. Am I missing something about this?

If you have an automatic bypass valve there will be minimal circulation

[jonstatt]

If you have an automatic bypass valve there will be minimal circulation

I apologise as I am sure I am being dense here. I do have a bypass valve, but I thought the bypass valve was set to be at a higher resistance than the heating loop so that water only circulates through the bypass loop in the event of the boiler pump over-run (i.e. both zone motors closed). If the heating zone is permanently open, then it just becomes one big loop with the water one which in total has lower resistance than the bypass loop.

[top brake]

I apologise as I am sure I am being dense here. I do have a bypass valve, but I thought the bypass valve was set to be at a higher resistance than the heating loop so that water only circulates through the bypass loop in the event of the boiler pump over-run (i.e. both zone motors closed). If the heating zone is permanently open, then it just becomes one big loop with the water one which in total has lower resistance than the bypass loop.

Have a look at this - in a feed and return system when the radiator valves are closed there is no flow

http://www.diydata.com/planning/central_heating/pipework.php#feedandreturn

Hence why you need a bypass valve

[jonstatt]

Have a look at this - in a feed and return system when the radiator valves are closed there is no flow

http://www.diydata.com/planning/central_heating/pipework.php#feedandreturn

Hence why you need a bypass valve

Ah fantastic...thanks for taking the time to find and point me to that. That makes a lot of sense. I guess I must have a "feed and return" layout because apart from the bypass differential valve being present, I had noticed no attempt had been made to balance my radiators (the stop valve on all radiators was fully open) yet all radiators get equally hot even if they are all fully on. So without ripping up floors or walls to see the pipe routing, I must assume that is what I have vs the much poorer but simpler single pipe loop.

Okay, well, I have just got my S-Plan set-up working.....but when I get a moment I will look at converting it into a figure 4 system.

[top brake]

Ah fantastic...thanks for taking the time to find and point me to that. That makes a lot of sense. I guess I must have a "feed and return" layout because apart from the bypass differential valve being present, I had noticed no attempt had been made to balance my radiators (the stop valve on all radiators was fully open) yet all radiators get equally hot even if they are all fully on. So without ripping up floors or walls to see the pipe routing, I must assume that is what I have vs the much poorer but simpler single pipe loop.

Okay, well, I have just got my S-Plan set-up working.....but when I get a moment I will look at converting it into a figure 4 system.

You're welcome

If you have Honeywell TRV you can balance the system at the TRV so your system may be have been balanced after all

[G4RHL]

I use my downstairs loo radiator as the bypass. Tiny room, always warm!

[jonstatt]

You're welcome

If you have Honeywell TRV you can balance the system at the TRV so your system may be have been balanced after all

They were Myson TRVs which don't have that feature.....but there was clearly no attempt to balance my CH. Nonetheless it has never been an issue anyway which is why I suspect it is the "feed and return" layout that you mentioned before which wouldn't need it to the same extent. My house was built in 2006, would feed and return be "standard practice" for new builds nowadays?

[jonstatt]

I use my downstairs loo radiator as the bypass. Tiny room, always warm!

It's funny you mentioned that because I started out without a TRV in my "under the stairs" loo as well, but it got really toasty in there...uncomfortably so Anyone would have thought I had done a workout in the gym when I left the loo rather than just having a tinkle!

[top brake]

They were Myson TRVs which don't have that feature.....but there was clearly no attempt to balance my CH. Nonetheless it has never been an issue anyway which is why I suspect it is the "feed and return" layout that you mentioned before which wouldn't need it to the same extent. My house was built in 2006, would feed and return be "standard practice" for new builds nowadays?

Feed and return standard practice, yes

You do need to balance the radiators to ensure best performance

[G4RHL]

How do you balance a radiator?

[G4RHL]

How do you balance a radiator?

Just seen the answer elsewhere in the forum. Having read it I don't need to balance, all my radiators seem to warm up at the same time and the lock valves are all fully open.