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Discuss System upgrade unvented etc in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. gingalig

    gingalig GSR

    Right, ok folks this could be a long one so please bear with me,
    I've been asked to replace a currently vented cyclinder with a new Unvented ( I'm G3 so dont worry,) as well as a bringing up to spec the rest of the system it has 16 rads and 3 bathrooms, its a pretty big sprawling house and the upstairs hot water pressure is rubbish as well as what look like aspestos F&E tanks in the loft, there is currently an external 26kw Grant oil boiler and what must at least a very agricultural looking 5000lt single skin tank with pretty much no seperation distances to non fire rated buildings and fences. ( Its currently supplying an ancient WB boiler in the attached annexe as well as the external one for the house)

    I've done the calculations including the annexe, and if I have them right the boiler should be a touch over 32Kw I'm thinking a Grant 26/36 external for ease of fitting and cost, and not having to renovate the only other available space if it were to be an internal boiler. I am also proposing a 250lt megaflow cylinder which is possibly a bit oversized but the run from the cyclinder to to boiler is quite a stretch and I'm a bit concerned about recycle times if the house is busy. I've been looking at a Tuffa 1350 ltr 60 min fire rated oil tank which is LABC approved but not Oftec, I spoke to Oftec and they say if it passes building control It should be fine.
    ( anyone have any experience of these ?? ) I have warned the owners that the current showers, pipework and fittings may not be up to the job. I would be powerflushing and fitting a magnetic filter.

    Looking at the existing system and pipework its a right mish mash with drop downs from all over the place although the radiators are all pretty new, I think it would be pretty difficult to zone effectivley with out completley re-pipeing it. At the moment it has an on/off basic timer with no room stat. I was thinking about Evohome but have never fitted one and would like to know if this is something that would be recomended and whether it would comply to Part L1b if it was required, as it seems to control individual radiators. On other minor worries and concerns I was also thinking about installing a timed recirculating pump for the hot water and possibly a secondary pump on the central heating system ??

    This will be my biggest job to date and I dont want to cut corners, or for it not to work effectivley. Any thoughts comments and ideas are welcome and indeed looked for, keep it clean gents, thanks in advance ;-)
     
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    What's the incoming flow and pressure?
     
  3. gingalig

    gingalig GSR

    Hi Shaun,
    I had it at just under 6 bar and 18 lts/ min at the outside tap
     
  4. gingalig

    gingalig GSR

    There was a funny looking PRV for the garden hose. Not sure if there was one in the house.
     
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    That's good just need to check that flow out
     
  6. king of pipes

    king of pipes Trusted Plumber GSR

    Ideally you need 20+ litres a minute and a dedicated 22mm minimum supply from the rising main you will not be able to supply 2 showers if you dont , i would allow a couple of extra days for any unseen problems you may encounter . Kop
     
  7. gingalig

    gingalig GSR

    I'm thinking an accumulator would probably be a good add on, although I'm beginning to head into uncharted territory. I'll go back and check there is no restriction on the incoming supply, the customer is very keen for mininmun upheaval although you cant make an ommlette with out cracking eggs so to speak. My main concern once i've ironed out the supply side of things is the zoning and whether I have to re pipe the main of the existing or can utilise whats there.
     
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