One pipe system

Discussion in 'Plumbers' Talk' started by Rachael19, Nov 11, 2023.

  1. Rachael19

    Rachael19 New Member

    We’ve moved into a property about 6 months ago, we have a aviant boiler fitted in 2022 but after having trouble with some radiators not heating up we got a couple changed, and found out we have a one pipe system. Since finding this out and reading up on it I think we need to get this made to a 2 system asap would help heating downstairs (lounge seems to be last in to get the heat) and before we have new flooring laid. can anyone tell me a good price, I’m really struggling to get more than 1 quote.
     
  2. The Happy Builder

    The Happy Builder Screwfix Select

    If it is a one pipe system with a replacement boiler the system other than the boiler probably needs replacing, including the radiators. What is the pipework made out of, thin steel or copper?

    Does a magnet stick to the pipework?
     
  3. Rachael19

    Rachael19 New Member

    The pipe work is copper, do you know if the new system could be fitted on to existing radiators to keep the cost down a little? What sort of price are we looking at?
     
  4. Jimbo

    Jimbo Screwfix Select

    Impossible to say here. Ultimately it means running a second pipe round practically the whole loop and all the disruption that will cause, as well as adjusting the piping to all the radiators.
     
  5. Rachael19

    Rachael19 New Member

    We’re in a 3 bed semi, quite large rooms and hall way so we have 8 large radiators and a towel radiator. I just want to know rough figure if we’re looking at 2 grand or 10 grand, if it’s nearer 10 grand then we’re going to have to wait awhile
     
  6. jimbobby

    jimbobby Screwfix Select

    Get 3 quotes from local plumbers
     
  7. techie

    techie Screwfix Select

    Where we live it would cost you £300 a day for one mans labour plus the materials and some profit added on top. Its not possible to create a number for you without seeing the work involved.
    Already mentioned is a one pipe system and as such is likely to be at the end of its life.
    There will likely be some making good and decorating needed as well
     
  8. The Happy Builder

    The Happy Builder Screwfix Select

    One pipe systems were generally last installed during the 1970's copper pipe shortage, which is why I asked if it is thin wall steel pipe, and was run as a single pipe to halve the quantity of pipework.

    Unless the original radiators have been replaced their delta T won't allow the efficient transmission of heat with the lower water flow temperatures of modern boilers.

    The radiators will also have fifty years accumulation of crud in them and rust.

    I doubt the system could withstand a serious power flush and I guess there is already crud accumulating in the heat exchanger of the new boiler.

    The whole system needs replacing.
     
  9. Rachael19

    Rachael19 New Member

    Thanks for the replies everyone. Guess it’s going to have to be done sooner rather than later. Managed to get a quote of £2000 then we supply radiators, will try and get another couple of quotes to compare at least I know a rough figure we’re working to
     
  10. Jimbo

    Jimbo Screwfix Select

    Be sure to specify pipe large enough for use with a heat pump in future
     
  11. Rachael19

    Rachael19 New Member

    Why?
     
  12. Jimbo

    Jimbo Screwfix Select

    Because you’re going to be paying for a lot of work re-piping the system so may as well consider now. It is unlikely that a gas appliance installed today will be able to be replaced like-for-like when it’s end of life.

    @arrow will be along to berate me for saying but it may well be worth getting a quote for the replacement of the system with a heat pump now since the government will pick up £7.5K of the cost.
     
    Abbadon2001 likes this.
  13. Rachael19

    Rachael19 New Member

    All except one radiator is new, they all have thermostatic valves on. Will we see a huge improvement by having this done?
     
  14. Jimbo

    Jimbo Screwfix Select

    One pipe requires a higher flow temperature than a two-pipe because the water cools on its way round the system. For this reason the
    last radiator needs to be larger relatively (because it is cooler than the first).

    Personally I’d try balancing what you have before spending what is likely to be a large amount on it. Turning down all of the radiators before the lounge will leave more heat left for the lounge.
     
  15. Rachael19

    Rachael19 New Member

    Thanks for all the replies. Really difficult to know what to do for the best.
    Can someone just clarify I’ve got this right, as all I can find diagrams on Google for one pipe systems and combi boilers have water tanks… we don’t have a water tank.
    The boiler has 4 pipes, one will be to the radiators and one the return from radiators, one will be the hot water and return of hot water?
    An upgrade will be an additional pipe that fill run round the house and into all the radiators?
     
  16. Abbadon2001

    Abbadon2001 Screwfix Select

    if you have a combi, one is fresh water in, one is hot water to taps, and the other two are feed and return to heating. If you change to a two pipe system, the return from the heating still goes to one of those heating connections, just now it will be coming from the new return pipe, which connects to each radiator independently.
     
  17. Tricky Dicky

    Tricky Dicky Screwfix Select

    One pipe radiator system at the top, 2 pipe system lower.
    Pipes.png
     
    Larry_129 likes this.
  18. Rachael19

    Rachael19 New Member

    Is it normal to have 7 pipes from the boiler?
     

    Attached Files:

  19. Tricky Dicky

    Tricky Dicky Screwfix Select

    Yes, if it's a COMBI boiler -
    Gas
    Cold water in
    Hot water out,
    Central heating output
    Central heating return
    Filling loop, for central heating pressure
    Condense outlet
    Where have the other 3 pipes suddenly come from

    PS - what is the approximate age of the property
     
  20. Rachael19

    Rachael19 New Member

    It was built in 1969
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice