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Best heating and hot water system for a full reno terraced 3 bed house?

Discussion in 'Plumbing and Central Heating' started by Oceans247, 29 May 2020.

  1. Oceans247

    Oceans247

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    Hi there,

    I am doing a full renovation on a mid-terrace 3-bed house (inc loft) and single-story rear extension. It will have 1 family bathroom with bath, and 1 ensuite and 9 to 12 rads (inc heated towel rails. Electric underfloor heating in family bathroom and ensuite.

    I was going to put in a combi boiler in the loft. Some people have suggested I look at getting an unvented hot water cylinder (but there could not really explain why).

    What are your thoughts?
     
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  3. WestmidsDIY

    WestmidsDIY

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    Has the property got a new cold water supply? If yes, an unvented system is worth considering.
    If you have the old water main, it’s worth checking the water pressure and flow to make sure it’s adequate for the unvented system to give multi tap usage.
     
  4. Oceans247

    Oceans247

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    Hi,

    Thanks for your reply. Yes I am replacing everything up to and including a new meter.

    Cheers
     
  5. WestmidsDIY

    WestmidsDIY

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    If you have a new water main into the property, you should have excellent mains pressure, so will get good hot water multi tap performance with an un vented cylinder and system boiler.
     
  6. bernardgreen

    bernardgreen

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    Only if the pressure in the mains is excellent, if the pressure in the street mains is 1 bar a new meter will not make it greater.
     
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  7. What has your chosen installer recommended ? they have seen your property and have had the chance to discuss your needs & demands. internet advice is just that (n)

    morning Bernard :mrgreen:, how is your anti gas combination boiler campaign going ?
     
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  8. bernardgreen

    bernardgreen

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    Didn't know I had a campaign,

    Combi's have their place, such as in a compact apartment occupied by a single person.
     
  9. picasso

    picasso

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    Where is the nutter that recommends gravity hot water system ? surprised he hasn't replied to this thread.
     
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  11. Madrab

    Madrab

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    Couldn't answer that until it's know what the mains can deliver (dynamic flow and pressure).
     
  12. Mr.B

    Mr.B

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    Well if you didn't know before, you do know. You're obsessed with it. You knock combis at every opportunity - one could almost liken your replies to a broken record.
    And, incidentally, I don't have a combi and am unlikely to have one - I've looked long and hard at them and choose to have something else - it's my prerogative ... in fact I used to sell them in a previous life ...but I don't bang on like boring old fart at each and every chance.
     
  13. muggles

    muggles

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    At the risk of actually answering the OP's question rather than bickering amongst ourselves (thank goodness hard-work hasn't jumped on this yet)...

    @Oceans247 you need to determine the flow rate and dynamic pressure of your water main before specifying a system. There's no point having an unvented cylinder if your water main can't keep up with it... As you're having a new main these tests will need to wait until that is complete, but you can at least find out your static pressure.

    An unvented cylinder would be preferable as it can supply multiple outlets at the same time, whereas combi boilers (regardless of make) are only really designed for one outlet.

    As for the inevitable question of "which boiler", take a look at Intergas
     
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  14. gasbanni

    gasbanni

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    Check your incoming mains blue 25mm mdpe go for unvented if not and it's 15mm stick with a combi.

    Ideal is unvented with 25mm mdpe mains.
     
  15. bernardgreen

    bernardgreen

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    That is a really good test..... Shouldn't you also measure the pressure, both static ( no flow ) and dynamic ( required flow ).

    A 15mm pipe with high pressure mains could deliver more water to the house than a 25mm pipe with low mains pressure
     
  16. Mr.B

    Mr.B

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    I'll be honest and say I only understand half of the above :

    Yes, I get the bit about 25mm blue MDPE being the best for an unvented set up due to the higher volume it can pass (although I also understood that both a decent flow AND a decent pressure is needed, and there's no mention of the latter).

    BUT, if I've got this right, you've said if there's only a 15mm incoming main, then stick to a combi --- however I thought it was well accepted that a respectable incoming pressure and flow was required for a combi to produce a decent hot water supply (ie it can't supply more than it's receiving). And if there's only a 15mm incoming main then how is that going to be any better for a combi than it is for an unvented?
     
  17. WestmidsDIY

    WestmidsDIY

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    I guess generally speaking, someone with a new water main you would expect to have better flow/pressure, of cold water. Before committing to expense a pressure and flow test would need to be carried out. There are several ways this can be done
     
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