Motorised valve position help needed.

[LisburnWhite]

Hi, need some help in where to fit a motorised valve that will be connected to a cylinder stat to stop the hot water from over heating.
There will be no valve on the central heating so that zone will always be open its only the hot water I will be regulating.
I can gain access to the pipework at position A or B easily and ideally this is where I would fit the motorised valve but if I need to change the pipework then I will.
Any help would be much appreciated.

 

[Riley]

Why not install two valves for complete control. The way you have it you will always have heating on to heat a cylinder of water

 

[Burger]

So I'm assuming there's no zone valve or cylinder stat at the moment? The reason I'm asking is you mentioned the cylinder stat - wasn't sure if you meant one already there or you are adding one. How is the whole system currently controlled?

 

[LisburnWhite]

Why not install two valves for complete control. The way you have it you will always have heating on to heat a cylinder of water

Didn't want to mess about with the pipework too much but if it's just a matter on installing a motorised valve then I can do that.
Would the valve for the central heating be on the output from boiler side I assume ?

 

[LisburnWhite]

So I'm assuming there's no zone valve or cylinder stat at the moment? The reason I'm asking is you mentioned the cylinder stat - wasn't sure if you meant one already there or you are adding one. How is the whole system currently controlled?

There are no zone valves or cylinder stat at present that is correct. It's CH and HW together at the moment via a time clock.

 

[Riley]

Fit a proper S plan system

 

[ShaunCorbs]

Need to upgrade it due to building control rulings

If you can get to a you can install a port valve to the rads

 

[steadyon]

1. Don't put it at A as it would mean putting a valve across the vent from the boiler, a safety No No.
2. Putting it at B would be OK, but marginally better on the flow just before where the flow pipe enters the cylinder, but after the tee to the vent pipe.
3. If you want both heating and hot water controllable, then another two port motorised valve after the pump in the flow to the radiators.
4. If you do use two x two port valves, you will need to fit an auto bypass valve between the output from the pump and the system return.
5. You could use a three port diverter valve, in which case you would not need the auto bypass. It would need to be after the pump and not impeding the vent pipe. Might be easier on the pipe work, but more complicated on the wiring. My own preference is 2 x 2 ports, as its easier to understand and in my experience the valves last longer.
6. I'd suggest you use Honeywell valves. They seem to last a decent amount of time. V4043 for 2 ports, V4073 for a 3 port.

 

[Stu-B]

If you’re not sure, get a professional in to help. Think of the summer months when you only need hot water, do you really want to be heating the rads too, that’s whats gonna happen going on your diagram. Like others said, fit an s plan, 2 valves, timer, stats and all the gubbins.
Save chucking £50’s out of the window.

 

[LisburnWhite]

1. Don't put it at A as it would mean putting a valve across the vent from the boiler, a safety No No.
2. Putting it at B would be OK, but marginally better on the flow just before where the flow pipe enters the cylinder, but after the tee to the vent pipe.
3. If you want both heating and hot water controllable, then another two port motorised valve after the pump in the flow to the radiators.
4. If you do use two x two port valves, you will need to fit an auto bypass valve between the output from the pump and the system return.
5. You could use a three port diverter valve, in which case you would not need the auto bypass. It would need to be after the pump and not impeding the vent pipe. Might be easier on the pipe work, but more complicated on the wiring. My own preference is 2 x 2 ports, as its easier to understand and in my experience the valves last longer.
6. I'd suggest you use Honeywell valves. They seem to last a decent amount of time. V4043 for 2 ports, V4073 for a 3 port.

Thank you for the quick reply and very comprehensive.
If I am understanding this correctly then I can put motorised valve at B (no room to fit between tee and cylinder on flow side) and this will work without changing other pipe work. However if I later want to control the CH zone separately then a motorised valve on it would require additional pipework with an auto bypass valve across output/return.