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Is it worth replacing my standard system boiler for a combi

Discussion in 'Plumbing and Central Heating' started by dominoman, 20 Jun 2016.

  1. dominoman

    dominoman

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    My boiler is on it's last legs. Its a 16 year old Potterton Suprima and it is making more strange noises again so I would like to replace it.

    I'd thought of a combi, but the quotes have come back at around £4500 because there is new pipework and it is quite a large house. Would I be better with a system boiler instead?

    Reason I thought to switch to a combi is that we may be moving overseas and renting out our house, and I thought combi would be more reliable.

    Some pics of my hot water tank mess are below (this is part of my motiovation for switching to a combi!)


     
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  3. Dan Robinson

    Dan Robinson

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    Those pics look familiar. Have they been posted before?

    Post more details on the house please.
     
  4. dominoman

    dominoman

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    Yes. You have a good memory! Those pics are the ones I posted 18 months ago when I was fixing the boiler and the pump last time. I patched it then (replaced pump, replaced leaking parts, powerflushed, fitted a magnaclean) but now it is starting to play up again by making loud noises when it starts. That's why i thought replacing the lot with a combi and getting rid of that mess would be best?

    The house is 4 bedroom Edwardian, on three floors, with large radiators (mix of cast iron and new ones), 2 bathrooms (one fed from the tank and one with electric shower). The boiler is in the cellar and that hot water tank in a cupboard on the first floor.
     
  5. handyjack

    handyjack

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    Like that T shirt :)
     
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  6. Dan Robinson

    Dan Robinson

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    Yes must remember to show it to SWMBO.
     
  7. Dan Robinson

    Dan Robinson

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    Personally, if the house is to be rented, I would stick with the open vented cylinder - just replace and tidy up that pipe work in the airing cupboard.

    Fit an intergas SB18 or SB24 in the cellar with condensate pump.
     
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  8. dominoman

    dominoman

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    Sorry. When I said System boiler I meant regular boiler. That's what I have now.

    I thought system boiler and regular boiler meant the same thing, but I've just seen that they are different.

    I'll have a look at those Intergas ones. I don't know that make. I want a boiler with a long guarantee so I can install and then forget about it (apart from annual service which I need for renting anyway)
     
  9. muggles

    muggles

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    Seven years guarantee on the Intergas, their HRE combi on which the SB and OV are based has just won the H&V Awards Product Of The Year. You'll probably want the OV to replace your Suprima. Only two moving parts in the OV so there's naff-all to go wrong, and everything's made of metal unlike some of the well known "premium" makes which are increasingly using plastic components
     
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  11. flameport

    flameport

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    Combis are not more or less reliable, but when they break, your tenants will have no hot water or heating until it is repaired.
    With a cylinder, they can switch on the immersion to get hot water, so boiler repair is less urgent.
     
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  12. Agile

    Agile

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    A combi boiler is more complex than a heat only boiler so potentially more likely to go wrong.

    But that is balanced by the added complexity of the cylinder, pump, motor valves and controls plus in your case a shower pump.

    But modern combi boilers are now very reliable and I always suggest they may fault once every three years. But many faults are caused by inadequate cleaning when installed so some will fault more often but that is not the fault of the manufacturer.

    However, the flow rate from a cylinder is higher than most combis so not something to spend a lot of money removing! Your system is about the most reliable possible.

    A replacement heat only boiler with condensate pump ( if no drain in cellar ) might be about £2200. But I have to say your cylinder is very old and probably rather overdue for replacement. A modern foam insulated cylinder will greatly reduce heat losses.

    If the dynamic mains flow rate is high enough ( like 22 li/min @ 1.0 bar ) then a replacement unvented cylinder would certainly be something to consider.

    Tony
     
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  13. dominoman

    dominoman

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    Many thanks Agile. Yes - it would need a condensate pump I think as the boiler is below the level of the drain. So the cost would be around £2200 fitted? That would certainly be a big saving over the combi.

    My flow rate is 14 l / minute (the guy tested it when he quoted for a combi) so probably not enough for unvented?

    I think I'll go for a new heat only boiler, and will also ask about replacing that old cylinder and tidying up the pipework in that cupboard.
     
  14. denso13

    denso13

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    Good grief.
     
  15. Agile

    Agile

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    That sounds like an open pipe flow rate.

    So not enough for a combi or an unvented cylinder.

    Tony
     
    Last edited: 22 Jun 2016
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  16. HootingOwl

    HootingOwl

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    OP has a mix of modern and old castiron radiators on the system so I would be looking to keep it open vent or put a plate exchanger on the heating circuit.
     
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  17. dominoman

    dominoman

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    Thanks all for the advice.

    My current boiler is a Potterton Suprima 100, which is rated at 100 BTU (29kw). I was thinking to replace it with a Vaillant ecoTEC Plus 30kW. Is that a decent boiler?

    It doesn't say it is a condensing boiler though.

    The other one I like is the Worcester Bosch Greenstar CDi Classic Regular 30kW
     
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