1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Valiant Ecotec 637 Low Loss header wiring

Discussion in 'Plumbing and Central Heating' started by Marc118, 19 Nov 2019.

  1. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi,
    I've been having issues with my heating which looks to be caused by poor flow around the system, see the previous thread;
    https://www.diynot.com/diy/threads/...-radiators-not-heating-up-fully.531129/page-3

    I had a gas safe registered company come in to take a look who suggested a low loss header, which I was already think of suggesting and he was supposed to come to carry out the works last week however his electrician has let him down, meaning that he can't carry out the works, or the controls side.

    Luckily I own my own engineering company and we carry out both electrical and controls works so I have offered to carry out this bit myself, if he is okay with that, which he is but he has said that he can offer no help on this because he simply doesn't know. This is the reason for my post on here. I'm hoping there is some one on here that can offer some advice as to how this should be set up.

    I've spoken with valiant technical this morning and he sent me the below image of how my boiler needs to be wired but to me this isn't quite correct because it only shows the one pump.

    I have a Valiant 637 Ecotec boiler and a hot water cylinder. I have three zone valves, upstairs heating, downstairs heating and DHW.

    We want to have an individual pump feeding each one of these zones. I already have a room stat for upstairs and one for downstairs.

    I know that i will need a wiring centre for this to work but unsure if that is the VR70 or VR700, if there's a difference and then a wiring diagram that is correct to my application.

    Can any one help?
     

    Attached Files:

  2. Sponsored Links
  3. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    I did something similar with a 438 boiler. Couple of points I'd make, which may be useful.

    1. It may be worth considering a single pump for the boiler and a single pump for the system side. With the boilers hex resistance taken away, you may find the system resistance is enough to be overcome with a single domestic pump. Do you know what your index circuits are for each zone?

    2. The boiler pump should be run directly from the boiler to allow for pump overrun.

    3. The system side pump can be run from the SL of the motorized valves (again, assuming a single pump). This is if you are using a standard S plan plus setup. With the vaillant controls, the wiring would be different.
     
    • Thanks Thanks x 1
  4. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi Fezster, thanks for your reply.

    I have 10 radiators downstairs and 7 radiators upstairs. My worry about only having the one pump would be that it still wasn't big enough to overcome the resistance of the pipework and I would only know once it had been installed.

    Your third point is interesting, could I piggy back off each 2 port valve to run the pumps without blowing a fuse for that output from the boiler? If this is how you did it, did you not use a wiring centre?
     
  5. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    You could use the SL from the thermostat (brown wire to honeywell motorised valve) to power the pump. I had this setup prior to my LLH install to power a separate pump on my d/s circuit. The only issue with it would be if the MV failed to open, the pump would run regardless, which could cause it to prematurely fail. I'm not sure if this is a valid concern or not.

    I think you may be surprised how much resistance needs to be overcome in the 637 hex and how little is left for the CH system. Once the hex is taken out, even a Grundfos Alpha 2 was sufficient for my system which consists of 13 radiators downstairs and 13 upstairs.
     
    • Thanks Thanks x 1
  6. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    I had this concern also. So I put in 50mm adapters to allow me to replace my 130mm domestic circulator with a 180mm semi commercial circulator, without any pipework alteration, if the former was not adequate enough.
     
    • Thanks Thanks x 1
  7. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    Did you do this without a wiring centre?
     
  8. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    I have/had a megaflo wiring centre and a honeywell one. But they are just junction boxes. This is a somewhat custom wiring job.

    I don't have a Vaillant wiring centre - in fact, you should check if the live coming from the VRxx is able to power the pump or not. In a standard S Plan setup, the live is taken from a fused spur.
     
  9. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
  10. Sponsored Links
  11. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    Instead I could use the end switch on my 2 port valve (assuming it has one) to power the pump, this way if the switch didn't open, the pump wouldn't run.
     
  12. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    before changing to a LLH, could I not just change the boiler pump to a bigger one or add one to the pipework to assist?

    Edit: Thinking about the second pump, there would be no bypass on the system for when all radiators close would there.
     
  13. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    Can I ask why you didn't go for the valiant wiring centre? I was hoping to have the boiler controlled from my phone with smart TRVs so what ever works I do, I want it to integrate in the best way possible.
     
  14. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    Depends - with the Vaillant wiring centre, yes. Because the boiler is fired via ebus, and the zone valve SL is disconnected. This could power your pump, and given the incoming Grey Live is off a switched spur, would mean it would be suitable regardless of current draw.

    However, in an S-Plan setup, the orange SL going to the boiler are all connected. This means if one zone SL is live, the others will be also. Hence, it would not be suitable for separate pumps on each zone.
     
  15. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    Yes. I tried this. I put a 25-80 on. It worked, but I preferred the hydraulic separation, and not having to use a non-domestic pump.
     
  16. Marc118

    Marc118

    Joined:
    12 Oct 2019
    Messages:
    33
    Thanks Received:
    0
    Country:
    United Kingdom
    Do you have a photo of the installation showing your LLH? I'm struggling to imagine how it will look and if it will be unsightly.
     
  17. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    478
    Thanks Received:
    57
    Location:
    London
    Country:
    United Kingdom
    Pm'd you a pic
     
Sponsored Links
Loading...

Share This Page