Single pipe heating system and new boiler.

Discussion in 'Plumbers' Talk' started by Clarry, Jun 17, 2016.

  1. Clarry

    Clarry New Member

    Hello all,
    Is it illegal under current regs to fit a new boiler to a single pipe radiator system? I understand the problems of lower efficiency and the likelihood of gunk from old system clogging up new boiler but the beneficiary of all the new efficiency is 87 years old so the cost and disruption of replacing the entire heating system seems out of proportion to the benefits!

    The boiler that has been condemned is an oil fired Worcester Danesmoor 15/19 with a rusty water jacket: I believe that's what the service engineer said but I am getting that info second hand.

    I would be very grateful for any thoughts/comments/ideas!
  2. I can't see how it's against regs, as the return water will tend to be much cooler than that in a conventional system and make condensing boilers more efficient - in theory.

    I have just that setup - a 'new' condensing combi on a one-pipe system (which is only 15mm for a large part of its run!)

    Yes, it's slow to heat up, and the last rads on the system don't get as hot as the initial ones, but it does work.

    But I have had issues with gradual releases of sludge blocking the P2P exchanger and finally clogging up the divertor valve, and that was despite removing all the rads for a hose-through, adding chemicals, and - latterly - fitting a magnetic filter (which really does help).

    My reasons were the same as the old cove's - just moved in with a new baby, and didn't want to disrupt too much at a time. I regret it now, but it's not a major issue.
  3. Oh, and for flushing, the individual rads will need doing separately, isolated from the system - 'cos you won't be able to 'force' cleaning fluids through them otherwise.
  4. Clarry

    Clarry New Member

    I gather the regs demand thermostatic valves on every radiator which would not work in a single pipe system. what if you installed a bypass pipe on every radiator so that if the valve closed the flow just gets diverted to the outlet side and on to the next radiator?

    Re flushing the system, I would guess that flushing pipework is fairly efficient? It's the rads that hold pockets of gunk. New rads seem cheap compared to potentially gumming up the new boiler so just replace them when you fit the bypass line.

    Am I missing something?
  5. KIAB

    KIAB Super Member

    The best best advice I will give, is rip the lot out & start from scratch.

    You can end up with so much hassle fitting a new boiler to scaled up old pipework, & flushing the system is never 100% effective.
    Better to do the main heating runs in 22mm pipe, as much as you can, & the drops down to the radiators in 15mm.

    As to boiler, Valliant, superb boilers can't fault them, easy to service, & fit a magnetic filter like Magnaclean or similar to the system, money well spent, will extend the life of the system.
  6. diymostthings

    diymostthings Well-Known Member

    If it is a true one-pipe system then each radiator will have a bypass - usually via a "swept Tee" to offer least resistnace to the correct flow direction.
  7. diymostthings

    diymostthings Well-Known Member

    I agree Vaillant are very good. I have also found the the Remeha Advanta plus range (now re-badged "Baxi") are also very good and seem good value. Concur absolutely with the Magnaclean.
  8. Crowsfoot

    Crowsfoot Screwfix Select

    The one pipe system is just a pumped ring main with stabs taken off to each individual radiator (which is dependent on gravity to circulate through the radiators). It should work
    OK; but beware double roads need 22mm valves and stabs (which no one manufactures anymore) also you don't need a lock-shied valve for balancing the radiators leaving them off will mean less resistance to the flow. Have you issues about taking up the floors?.
  9. I understand you can get 'full bore' TRVs for one pipe systems. I ended up fitting normal ones to mine, and they seem to work ok.

    But, a one-pipe system will always be a compromise. And - worse - such an old system will almost certainly have lots of gunge sitting there ready to cause harm.
    KIAB likes this.
  10. Clarry

    Clarry New Member

    OK guys, thank you so much for your thoughts, it all helps me have some clue what I am being offered:)

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