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Discuss C plan plus... would a c plan work with 2 heating zones? in the Central Heating Forum area at

  1. Lozza

    Lozza New Member

    Hi all

    Need some tips. I have what is effectively a C plan system but want to split the heating into 2 zones. I have a 2 port 28mm valve on the hot water. Looking at the c plan wiring diagrams, would it work to have the zone valves off the thermostat circuits and the call for heat into the white cable of the 28mm valve. I'e added a picture of what I'm thinking. Any pointers?

  2. kris

    kris Trusted Plumber GSR

    So it'd be like a C plan plus ,,,, but with an extra plus lol
  3. Lozza

    Lozza New Member

    Something like that? Any perceived issues with current backflow anywhere?
  4. king of pipes

    king of pipes Trusted Plumber GSR Top Contributor!!

    Shaun this ones for you mate , if i was installing it each zone would have its dedicated valve . kop
    • Like Like x 1
  5. Lozza

    Lozza New Member

    Hi. The drawings not great I know - I've tried to show 2 valves - v1 and v2, off the respective stat circuit, with the CFH coming together to the white of the 28mm valve (allowing the boiler to fire without the pump for HW only).
  6. SavageW

    SavageW Plumber GSR

    Do you want each zone for your ch to be programmed differently to each other? Or do you just want to add a zone that can be either on or off from an additional thermostat. If the latter, would be a case of hard wiring to a 2nd thermostat or easier in my opinion wiring it to a wireless thermostat.If you want each zone separately programmed I’d look at the internet/wireless/smart whatever you want to call them controls with multi zone
  7. Lozza

    Lozza New Member

    Hi. Separate thermostat controlling each one, but on the same schedule. Because hw isn't pumped my issue is firing the boiler for HW and boiler with pump for CH. The diagrams on the net all show c plan but without zone valves for the CH. I guess fundamentally I'm trying to ascertain whether adding the valves between the thermostat return and the 28mm white cable would allow independent control of the heating zones.
  8. Lozza

    Lozza New Member

    Sorry - replied as an additional comment.
  9. SavageW

    SavageW Plumber GSR

    It’s hard to understand over the forum sometimes,do you want to have HW & CH on at the same time? Your current set up would be priority HW.If you want both CH zones programmed the same then you just need CH ON from programmer to go to Stat 1 & Stat 2 with the switch live from Stat 2 going to the same junction as Stat 1. Have you looked at where your additional zone valve is going to be installed
  10. Lozza

    Lozza New Member

    Ok, so independent hw and ch. I'e 2 stats fitted. I want 2 zone valves for 2 heating zones. So I need to keep the 2 sl seperate and then take the brown to each zone valve from those. My instint then says that if I take the 2 orange CFH together, and out to the white of the 28mm hw valve, I'll be able to have heating and hot water independent of each other, and only powering the pump when the heating is on.

    Tried again on the ďiagram. I'm 'adding a seperate terminal between 5 and 6 that has the SL from the zone 2 stat. Terminal 5 goes SL to zone 1 valve, Terminal '5a' goes to SL to zone 2 valve, then both valves return their Call for Heat (orange) to the terminal 9 to provide power to the boiler. If either circuit goes live the boiler fires. If the 28mm HW valve goes live then the boiler circuit is made from the permanent live, and pump is is unpowered as there is no circuit across terminal 9.

    Last edited: Mar 12, 2018
  11. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    In simple terms no separate times

    But it's gravity hot water and pumped heating

    Hot water work like normal but boiler is set to 65 normally

    And the port valve works on the cylinder stat

    Cylinder upto temp port valve closes and bypass is the heating system on gravity so one or two rads will tend to heat up

    All that controls the heating is the prog and room stat no port valve for heating

    Room stat turns the pump on and off
  12. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Op your best bet is to turn the hot water into pumped and then just s plan plus it

    Simpler in the long run and you will get better efficiency out of your system

    If you really want to keep your system as is you will need a heat leak rad for your cylinder

    And then you could zone it how ever you like
  13. Lozza

    Lozza New Member

    Bit is there an issue with fitting valves to the heating side?
  14. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Next post down from the one you quoted
  15. Lozza

    Lozza New Member

    Thanks guys. So leads me to another question. I don' think that there is a heat leak rad in the system at the moment. Why would this now be needed? The boilèr (oil fired Camray 5) has 2 outlets - one of which heads to the HW and the other to CH which then splits to the upstairs and downstairs rads). Other than adding motorised valves into these 3 aspects, nothing has changed. Why would I now need a heat leak?
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