Changing a 2-port valve to a 3-port valve

[CRJ1965]

G'day Folks - just moved house, and our new abode has a 70's vintage CH/HW system (although the boiler is only around 7yrs old)

At the moment there is one 2-port valve installed which allows the HW only to be fed, or both the HW and CH to be fed simultaneously. There is no way to have just the CH on independently. I am sure of this for two reasons:

1 - I have scoured the house for a second two way valve with no success.
2 - when you try to select CH only on the programmer, both the CH & HW lights come on.

Anyway, what I would like to do as an interim improvement (can't afford to stump up for a shiny new boiler yet) is to replace the 2-port valve with a three port valve. Obviously it would require a rethink on the wiring, but hopefully that won't be too much of a drama.

Anyway, cut to the chase, is this as straightforward as it seems?

 

[twgas]

It might require a rethink on the plumbing as well

 

[CRJ1965]

in what respect? it looks like a 3-port valve will fit in the space....

 

[Newboy]

and the third port will be connected to ......... ?

 

[twgas]

and the third port will be connected to ......... ?

do all 3 ports have to be connected

 

[CRJ1965]

I've attached a schematic to explain things.....

At the moment the boiler will always circulate through the HW cylinder. If I select CH.

 

[CRJ1965]

Untitled

• CRJ1965
• 24 Sep 2013
• 1

 

[CRJ1965]

here is what i am thinking of converting to...

Untitled

• CRJ1965
• 24 Sep 2013
• 1

Obviously I may have got it wrong, if so then advice is very much appreciated.....

 

[gas112]

Far easier to just put another 2 port on flow to cylinder after it tees off

 

[CRJ1965]

Thanks gas112. I'll have a look at the wiring later, post a pic, and source help on wiring!

 

[twgas]

If you go for another 2 port, which is probably easiest, here's a wiring diag
https://www.google.co.uk/search?q=s...hl=en&client=safari#biv=i|0;d|D2hSlhbpBXBPZM: