Boiler for loft conversion

Discussion in 'Plumbing and Central Heating' started by reggie13, 26 Apr 2021.

  1. reggie13

    reggie13

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    Hi all, I’m looking to get a dormer loft conversion in my 3bed semi. There will be one bedroom and shower room in the loft, and 13 rads in total . My current Viessmann 200w system boiler, H/W cylinder and cold water attic tank will be coming out.

    I’ve got used to the low pressure / avg flow rate. So what type of replacement boiler or type of system should I be looking at for something similar in the loft? Combi storage boiler, normal combi? I will get the lead main pipe upgraded to MDPE pipe. BTW: wife likes the idea having more space in 1st floor bathroom with no H/W cylinder in airing cupboard.

    Thanks in advance
     
    Last edited: 26 Apr 2021
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  3. oldbutnotdead

    oldbutnotdead

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    This topic has been done to death a few times, search in this forum for combi or system and you'll find a lot of discussions.
    Precis- there's no such thing as a free lunch. If mains pressure/flow is poor a combi will perform badly, your better solution will be stick with cylinder & fit shower pump(s). Most combis won't deliver enough hot water for 2 simultaneous showers. You can have a hybrid solution (combi and dhw cylinder). You could have 1 electric shower and one combi shower (tho the electric will be a poor experience compared with the combi).
     
  4. reggie13

    reggie13

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    if I stick to cylinder with shower pumps won’t that mean keeping the cold water tank in the loft?
     
  5. JohnD

    JohnD

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    You could move forward into the 1990's and get an unvented cylinder, and throw away your cold tank, pump and your electric shower.

    What's wrong with your current boiler?
     
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  7. reggie13

    reggie13

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    Nothing wrong with it, but need to remove the cold water tank from the attic, so I assume it won’t be usable ? Is that valid assumption? Also it’s 26kw, not sure if that would be sufficient going forward
     
    Last edited: 26 Apr 2021
  8. muggles

    muggles

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    More likely to be massively oversized. My 1970s 4 bed semi runs quite happily on 11kW (heat loss is actually 9.5kW), and presumably with your loft conversion you'll be improving insulation levels over what you have now. As a very rough rule of thumb in most houses you need 1kW per radiator, so 13kW in your case once the conversion is complete.

    As others have said, look at the possibility of having an unvented cylinder installed, which doesn't require a loft tank. You have an excellent boiler and I wouldn't rush to change it
     
  9. reggie13

    reggie13

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    Ok, thx everyone, will take a look. An unvented cylinder can be placed on any floor, and hooked with pump ? (the ground floor has most space)
     
    Last edited: 27 Apr 2021
  10. dilalio

    dilalio

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    Unvented can't be pumped on outlets.
    It can be fed by a whole house pump/accumulator setup if incoming mains is really poor. Get your water supplier to test flow and pressure at their meter.
     
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  11. DIYnot Local

    DIYnot Local

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