wiring up a 2 zone heating system

Discussion in 'Plumbing and Central Heating' started by profet, 2 Mar 2010.

  1. profet

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    My first post - so go easy on me! I've looked everywhere for the answers to these questions, so maybe one of you will be able to help.

    I've just had a completely new heating system put into my house - we have two zones - one for sleeping areas and one for the rest of the house.

    We have a Worcester combi boiler that provides the hot water and central heating. There are two 2-way valves - one for each CH zone. There are also two thermostats. All the cables run back to the boiler but aren't connected yet (we manually open and close the valves by hand as needed).

    My question is this - do we need to connect the two room thermostats to a dual zone heating controller (just a 2 zone timeswitch as far as I can tell), or can we just use two programmable thermostats instead? I'd rather go with the two programmable stats because that would allow us to actually change the temperature over time. I assume the stats would work by operating a valve each, but how do they work together to turn the boiler on and off - or do they not have to do that at all?

    I guess what I'm asking is can I get away without a central timeswitch, and just use the ones built into the programmable thermostats. Any chance of a wiring diagram to help or it is really a job for an electrician?

    Oh, we had an automatic bypass valve put into the system so that the valves could both be in the off position without preventing the boiler from dissipating heat after heating hot water.

    I hope I am making at least some sense - thanks again for any help you guys can offer!
     
  2. darren17

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    much better to use 2 programmable stat's then they are independant.
    what is the make of the controls.
    the stat's call for heat when they drop in temp.
    did you get any trv's fitted ??
     
  3. profet

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    Hi darren17 - thanks for your reply!

    We just have two bog standard dial type room stats so we can buy whichever programmable stats you recommend! TRVs are fitted everywhere, but we would obviously take them off in the two areas with the room stats.

    So thats sorted - two programmable room stats instead of a dual zone programmable controller. The problem is going to be how to connect the two stats, the two valves and the boiler together.

    Will I just be able to take of the existing dial type stats and put on the programmable ones?

    Thanks again!
     
  4. onlyfitidealboilers

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    use wireless controls ie Drayton RF1 this means the stats dont have any wires! these are good bits of kit
     
  5. profet

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    Hi onlyfitidealboilers,

    We had the two stats installed already before the re-plastering was done, so the wires are already in place. I guess it'll be cheaper, and maybe more reliable to use them since they are there.
     
  6. darren17

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    there are a lot of different programmable stat's.
    i generally use either salus or danfos.
    just bare in mind that you can get wired or wireless.
    you can get a control pack which has the wiring center , the wireless stat's and the rf reciever's , it also has a full wiring diagram.
    the beauty of wireless stat's is you can move them easily and another place could be the control temp.
    if you have 2 stat's already fitted then all you have to do is use the model number to google it and you will get the full diagram.
     
  7. onlyfitidealboilers

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    have you got programmable room stats? if so fit two honeywell CM921 stats/room stats. you can buy hard wire ones.. be about 80 quid each plus installation.
     
  8. tamz

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    You can use 2 std roomstats unless you also want to time control the zones in which case get programmables. As you already have the wires in place use wired ones.
    These instructions will do for both types but you will need to link L - com in programmables.

    Put a joint box with 6 connections next to the motor valves and take the stat wires and motorised valve wires to it.
    Take a 4 core from the boiler to the box.

    Connect from boiler,
    Ls to common from both stats and both grays from valves
    Ns to N from valves and stats if present
    E to E from valves
    Lr to both orange from valves

    Wire call from stat 1 to brown on valve 1
    Wire call from stat 2 to brown on valve 2

    If you want to stick a programmer on instead of programmable stats connect commons from stats to programmer switches (1 on each channel) and take L & N from box to programmer.
     
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  9. profet

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    Thanks again everyone - especially tamz! I wired everything up at the weekend into a nice little honeywell wiring center I bought on ebay), and it all worked perfectly first time! Stats open and close the zone valves, and in combination fire the boiler.

    At the moment I'm just using two regular non-programmable room stats - can anyone suggest a good, and not overly expensive programmable stat I can use? The wires are already in the walls, so I'd prefer wired ones as opposed to wireless.

    Also, will it just be a simple matter of taking off the old stats and putting the new ones one - or will there be other issues?

    Thanks guys! Photos of my nice neat wiring will follow in case it ever helps someone else in my position.

    edit: thinking of the ECO ET2 -
    http://www.tfc-group.co.uk/_sa_webapp/runa2a3.html?page=320
    Sound ok?
     

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