I want to improve my gravity fed hot water by adding a pump

[picasso]

the switch in the 28mm valve is a simple changeover switch, when you call for hot water the valve motors and connects a permanent live (grey wire) to orange firing the boiler (gravity hot water so no pump) if ch is called at same time the pump is feed through room stat , boiler is all ready running .

ch on its own is room stat > pump > white wire on 28mm valve, the white wire is connected to the orange firing boiler, if you look a d hailshams c plan diagram you can follow the switching.

 

[Andygasman2010]

Yes, independance can be achieved this way. That's what a C-plan is designed for but it can't sucessfully operate a second pump for the hot water without problems.

Pump issues aside...

Then internals of a 5 wire head vs a 6 wire head are essentially the same except the microswitch is used in a slightly different way.

Are you familiar with 3 pin microswitches having C - NC- NO ?? If not then this could be difficult to understand. On a C-plan head...

Gray is still permenant live

Orange goes to the boiler only (note: not a pump)

White is not a feed out of the valve but acts as a path through the valve for voltage to get from the room stat to the boiler.

 

[picasso]

there is nothing stopping you putting the pump live on the cylinder stat c/brown to valve connection as I think ironman has already said.

 

[Andygasman2010]

there is nothing stopping you putting the pump live on the cylinder stat c/brown to valve connection as I think ironman has already said.

Edit!

Just re-read what you said there, my mistake.

 

[Fastlearner]

Hi guys,
I have to thank you all for unstinted patience with my enquiry. I think i have at least a partial understanding as regards the fundamental operation of the 6 wire 2 port valve.It would seem that both HW & CH sytems are designed to function via the valve & that in both cases the brown wire must be energised in order that the white/orange function to the boiler is completed.Thus i can appreciate that the live to the 2nd pump(HW) should be brown & fed from C of the cyl stat.This seems fairly straightforward regarding the HW circuit.Similarly if my understanding is correct the brown circuit to the valve must be completed for the CH to function,hence the suggestion to link brown from the CH pump to the brown of the motorized valve to complete the white/orange link to the boiler, which will create unwanted back feed to both pumps when required to operate separately.This was outlined by Andygasman 2010 earlier today.
Just read your post JohnD.Clearly there is an understanding in the forum that i have or have factored in another valve at the CH pump which at this time i have not.It would seem that some ideas relate to 'S' plan & some to 'C' plan.I really need to get my head around the wiring to this CH valve.
Ron

 

[JohnD]

you can use the stat to turn on the pump and open the valve; and the valve-open switch to fire the boiler.

That way there is no back-feed to the other pump, since current can only get to the other pump when the other valve is open, and the switch is therefore on. When the other valve is closed, its switch is off.

The programmer timer controls power to the two stats.

 

[ironman1]

I'm getting confused as to what controls you're using?.................i thought you were using 2 two port valves?................it now seems that you are using a 22mm two port for hot water & just a pump for central heating with no zone valve.........................................pretty straight forward to use the 22mm motorised valve you previously mentioned.......................with a two channel programmer HW (#3) would be fed to common on cyl stat , #1 from cyl stat would be fed to brown wire on motorised valve along with feed to pump , orange wire from motorised valve would feed boiler...............................CH feed from programmer (#4) would go to live on room stat , switched live from room stat would feed live to pump & boiler (backfeed).................simples. ..............................but then you have the problem whereby when hot water is calling central heating circuit will also be active due to hot water pump reverse circulating heating circuit , this is why 2 two ports should be used....................just fit another two port to heating circuit & all is good , pumps should be wired via previous post.

Fitting a 28 mm zone valve to HW circuit won't stop reverse circulation around heating circuit when hot water is calling , you need to fit a zone valve to heating side eliminating reverse circulation.

 

[Fastlearner]

Hi once again,
I haven't done any serious practical work at this time.I have bought the 22 mm valve( Honeywell V4043H 1056) which i presume can be used for CH zone valve & cyl stat.I presume that i should be sourcing a 28mm valve(Honeywell V4043H1106) to use on the HW side.I'll put this on hold until i satisfy myself how the valves/pumps/boiler link up electrically.Brain currently on overload.Many thanks guys.You're a patient lot.
Ron
I think i may have finally found the plot.If i am correct, both motorized valves can be 22mm 5 wire versions.If there is any advantage by using the 28mm version ,please advise.Just to re cap;Both motorized valves have to be energised by the brown switched live of the cyl stat & room stat respectively ie. on CH side room stat > CH pump > brown/motorized valve.If there has been no demand from the programmer,then the valves remain closed.The orange from the 2 motorized can then be linked as a common feed to the boiler.If the individual valves are not energised & therefore closed, then there will be no backfeed along the orange wire.Ironman 1...........Please tell me that's correct....simples

 

[ironman1]

..................you are CORRECT Ron.........................no need for that 28mm motorised valve................IF you did happen to use a 28mm motorised valve along with a 22mm valve you would wire it exactly the same as a 5 wire BUT white wire would not be used & 'parked up' , in this case it would work exactly the same as a 5 wire....in other words you would use a 28mm motorised valve if pipework was run in 28mm , just that the white wire won't be needed.


Glad you finally sorted it , you sound a decent fellow.

 

[picasso]

so are you going for the s plan with one pump or do you still intend fitting a second pump ?

 

[Fastlearner]

Thanks again guys for all your help.This is my first posting & i can't praise the concept & execution enough.Just one last throw of the dice if you'll bear with me.
At this stage i am proposing to use the 2 pump system.
The confusion has arisen because i did not consider the need for a CH zone valve.My current system is completely standard gravity HW/pumped CH.I did not think a CH zone valve needed to be designed into the modification because; a) 4 separate boiler connections for HW & CH
b) New HW pump would be on lowest setting & balanced by pump gate valves.
c)CH pump is 15metres from boiler & fed by 2 flows & return (not sure of the particular relevance to this issue)
I can now understand that a CH zone valve will ensure independant operation of HW/CH boiler feed but does it serve any significant purpose regarding water flow control in my case.
Depending on attitude to that comment there have been suggestions that a relay between the CH pump/boiler common feed would serve the same purpose.
If the zone valve was not crucial for CH water flow control, i would be concerned that if it failed on Christmas Day the pump would be spinning & no flow.Presumably a failed relay at this time would allow short term speedy intervention.
On the subject of zone valve failure, is it considered good practice to site it on the return side of the pump which can/will continue to spin? If it's on the flow side of the pump and it fails, will the pump be spinning with restricted cooling.In my case the CH zone valve is easier sited on the flow side of the pump.

Once again many thanks for your help.
Ron

 

[picasso]

keep it simple, a 28mm 6 wire zone valve on the hot water, a pump wired into the cylinder stat, you dont need a central heating zone valve and wired up as a conventional c plan with the addition of a second pump, straight forward to plumb and wire.

 

[Fastlearner]

Hi Picasso,
So you don't accept that there are electrical 'back feed' issues with individual HW & CH pumping.
Ron

 

[picasso]

the switching inside the 28mm 2 port seperates the hw from the ch, you will need a relay if you go for the 2x2 port valves and 2 pumps, for ease of plumbing and wiring the c plan is the way to go.

 

[Fastlearner]

Hi Picasso,
I'm getting confused again.The reason for adopting the 2 pump option was because the HW tank that i have is for 'pumped only' systems and my understanding is that 'C' plan retains the gravity element.I am advised by RM cylinders that this tank will not 'gravity cycle'. This whole project has been born around that premise and that bone fida gravity tanks are specialist sourced.If i could acquire a tank designed for gravity,then the easy option would be a straight swap.My other understanding from other contributors was that switching HW & CH circuits was not effected within the 28mm valve and would in the case of 'C' plan connect the CH pump to the boiler via the orange output.Maybe my understanding is flawed?
Ron
Just read again your posting @ 12-13 today which suggests that the 2 pumps can be operated independantly by using only the 28mm zone valve.I can see how that could work if the brown of the valve didn't need energising to complete the CH circuit ie. connecting white/orange.My understanding is that it does need energising,hence the potential backfeed issues & therefore alternative suggestions to install a CH zone valve.
Ron