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Motorised valve position help needed.

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Discuss Motorised valve position help needed. in the Plumbing Jobs | The Job-board area at Plumbers Forums

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LisburnWhite

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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.
photostudio heating.jpg
 
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
 
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?
 
Riley said:
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
Click to expand...

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 ?
 
CBW1982 said:
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?
Click to expand...

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.
 
Need to upgrade it due to building control rulings

If you can get to a you can install a port valve to the rads
 
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.
 
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.
 
steadyon said:
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.
Click to expand...

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.
 
If it’s not pumping over (which is a bit of a surprise) then at least it’s not drawing in air. Like others have said I would take the extra time and a little extra money to convert to an S-plan. You’ll have fully independent, thermostatic control over both load circuits which as mentioned above complies to current regs and will save you a lot of money.
 
SJB060685 said:
If it’s not pumping over (which is a bit of a surprise) then at least it’s not drawing in air. Like others have said I would take the extra time and a little extra money to convert to an S-plan. You’ll have fully independent, thermostatic control over both load circuits which as mentioned above complies to current regs and will save you a lot of money.
Click to expand...

I think it was originally just solid fuel heating. This has been taken away and an oil fired boiler fitted hence the jumble of pipework. Works fine at present and that's why my reluctance to change it too much. Was thinking that the small amount of work to fit cylinder stat/valve would give me at least a measure of control over the hot water.
 
As it stands you have a fully pumped system but without any independent zones or thermostatic Control. As you know when calling for HW you’re getting CH and vica versa and I assume the boiler is just cycling on and off, even when cylinder and/or heating are up to temp. Whatever you choose to do a certain amount of pipework and wiring is going to be needed, so if you’re going to spend money I would spend a bit more. I dread to think how many litres of oil you go through as it is
 
LisburnWhite said:
I think it was originally just solid fuel heating. This has been taken away and an oil fired boiler fitted hence the jumble of pipework. Works fine at present and that's why my reluctance to change it too much. Was thinking that the small amount of work to fit cylinder stat/valve would give me at least a measure of control over the hot water.
Click to expand...

Yes it would, but having control over your heating also saves you money long term. As recommended, upgrade, but your call.
 
If it wasn’t pumping up, it will likely now if you mess about putting a mv on the cylinder.
That cylinder is at present giving an easy path through coil and back to boiler for the water. Close it and the vent and feed become an easy path to pump over.
This has been a very common pipe set up in most older heating systems I come across and there rarely is an easy stick a zone valve in fix.
S plan, using 2 valves and with system sealed if suitable.
Get a heating installer to do it
 
steadyon said:
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.
Click to expand...

Very sorry but I had another look at the boiler and the pump is actually on the return side drawing the water back into the boiler.
Would this make any difference to where I could potentially fit the motorised valves and bypass valve or is it just a complete mess.
Here is a new drawing, sorry for not double checking.
boiler pump.jpg
revised.jpg
 
That circulating pump is very old as clearly it is the large motor Wilo Gold.
I wouldn’t trust any of that install judging by the twin wall light metal flue straight down on top of Warmflow boiler. :eek:
 
Best said:
That circulating pump is very old as clearly it is the large motor Wilo Gold.
I wouldn’t trust any of that install judging by the twin wall light metal flue straight down on top of Warmflow boiler. :eek:
Click to expand...
Yeah think it's about 25 years since it was installed. Can't afford to fork out too much at the moment so was looking for a reasonably quick way to at least sort out water in tank overheating.
 
Thanks for all the guidance and suggestions.

Was able to squeeze the MV between the vent pipe and the cylinder. Got it wired up to the cylinder stat and everything is working well with no pumping over.
Going to buy another MV and a wall stat to control the rads and fit an auto bypass valve (when I have the time and get a few quid saved)

Again thanks for the help.
 
LisburnWhite said:
Thanks for all the guidance and suggestions.

Was able to squeeze the MV between the vent pipe and the cylinder. Got it wired up to the cylinder stat and everything is working well with no pumping over.
Going to buy another MV and a wall stat to control the rads and fit an auto bypass valve (when I have the time and get a few quid saved)

Again thanks for the help.
Click to expand...

What will happen when the both zone valves turn off that you plan to fit?
 
Best said:
What will happen when the both zone valves turn off that you plan to fit?
Click to expand...

When both hot water and room stat hit their settings both valves will turn off. When this happens there will be no call for heat from boiler/pump and they will turn off. The bypass valve between flow/return is more for safety and saving the pump I think in case a problem occurs and for some reason the boiler/pump is running when both MV closed.
 
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