extending valve wiring

[honda]

hi all, my first post so please be gentle. after reading all relevant posts i'm contemplating updating my GHW system by adding a 2 port zone valve in the return. ( i'm fully aware of the dangers of fitting it in the wrong place). my problem is:- because of the physical layout of the existing wiring i would need to extend the 6 core tail on the valve by approx 5 mtrs so as to link to the existing wiring for the boiler, pump, room stat and cylinder stat. naturally i want to keep this legal but can't find a suitable 6 core cable. is there one and if not what do i use. thanks.

 

[corgiman]

Are you competent as per Part P

 

[honda]

I'm competant enough to do it but not competant as per part p

 

[Nige F]

hard wire in 2x 3core(+earths) in your own home

 

[honda]

thanks nige f. that's the only way out i could see and would do for me but was hoping to keep colour code maybe for future owners. is there any way of doing so?

 

[twgas]

try labelling the cables for ID purposes

 

[honda]

thanks twgas. looks like that's the way to go.

 

[bengasman]

mv should always be in the flow, why do you want to put it in the return?

 

[honda]

Hi, i'm putting it in the return as per c plan. if i put it in the flow then it will block the vent pipe. as mentioned it's a 2 port valve i intend to fit to control temp of dhw, are you mistakenly thinking of 3 port valve which connects to flow? not being a professional i stand to be corrected and welcome any comments/criticism you may have before i do it.

 

[twgas]

Hi, i'm putting it in the return as per c plan.

it needs to be between cylinder and cold feed connection

 

[honda]

yea thanks for that mick. have room to fit it in that posistion as i altered return pipework a long time ago to fit cyltrol valve (which i subsequently removed when it seized up.

 

[honda]

hi, looking at the wiring diagram for the c plan it looks like when i get it done i'll have seperate control of HW and CH. the instructions for the programmer state that with a gravity system one should not be able to select CH without having HW on also. does the fitting of the 2 port valve enable me to have seperate control as per diagram?

 

[honda]

should have added that the programmer has 2 dip switches. one for fully pumped system and one for pumped CH & gravity HW. which do i select once i've fitted the valve in the HW return?

 

[honda]

Hello?

 

[bengasman]

Hi, i'm putting it in the return as per c plan. if i put it in the flow then it will block the vent pipe. as mentioned it's a 2 port valve i intend to fit to control temp of dhw, are you mistakenly thinking of 3 port valve which connects to flow? not being a professional i stand to be corrected and welcome any comments/criticism you may have before i do it.

c-plan has one valve. If you change to 2 valves it is therefore not a c-plan but s-plan.
You can now get all sorts of interesting situations depending on how bad your system is, where excess pressure will go and where the sludge will end up.
With a bit of (bad) luck your “cold” water tank starts to function as a bypass, collapse and poor boiling water over the controls beneath it.
Fortunately it will not stay hot long as there will be cold water following it until somebody turns it off. If that happens when you are asleep, that could well be 2000 litres later.
Or the flow can be shut off with the boiler overheating and the pressure has nowhere to go because the valves are shut.
Think again before you carry on with this adventure, at the very least do some serious reading on heating design and control systems.
Before you do anything else, map your entire system. If you can not do that AND be 100% sure that your drawing is an accurate representation of your existing system, including existing faults, do not go further.