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  • FIRST POST
    • mickeyb102
    • By mickeyb102 17th Apr 17, 4:34 PM
    • 3Posts
    • 0Thanks
    mickeyb102
    Love or Hate your Combi Boiler?
    • #1
    • 17th Apr 17, 4:34 PM
    Love or Hate your Combi Boiler? 17th Apr 17 at 4:34 PM
    Hi, I am looking to replace the warm air heating in my home and would appreciate any views. We have a 70's style detached house with 4 bedrooms, single bathroom and downstairs cloakroom. The heating engineer has given us 2 options

    (1) Vailant EcoTec 832 combination bolier
    (2) Vailant ecoTec 630 boiler with a Main unvented hot water cylinder.

    Both would have 11 radiations and we were thinking that we could remove the electric shower over the bath and run this off the new system as well.

    The engineer is trying to push us towards option 2. He said that combi boilers are more complicated and so less reliable. He said, in winter, the water flow will be slow as the mains water will be colder. Is this really the case? We like the idea of the combi and would be most grateful for any advice from anybody who has one of these. Has it been reliable. is the flow ok when say running a sink tap and bath, does it work well with a shower. Thank you very much.
    Last edited by mickeyb102; 17-04-2017 at 4:50 PM.
Page 2
    • fezster
    • By fezster 19th Apr 17, 3:02 PM
    • 166 Posts
    • 83 Thanks
    fezster
    Nobody seems to have mentioned the Achilles' Heel that unvented systems have; namely, what happens when the water is turned off by the supplier? Whether that be for repairs in the street, contamination or the overdue 1976-style drought, you'll be able to flush your toilet just the once, have no hot water to wash your hands afterwards and no cold to even make a cup of tea.
    Originally posted by Kernel Sanders
    Same for a combi. Only a cold water tank or an accumulator setup would overcome this, neither of which are being considered by the OP.

    A combi will run one shower at most. And this will be affected by the opening of another hot outlet simultaneously (i.e. the shower may go cold). You can get bigger combi's to try and overcome this, but no combi will run 2 decent showers all year round. You have to offset this against the convenience of hot water on demand.

    Having had an unvented setup, I'd definitely prefer that, unless space prohibited me from having one. You do need to make sure your incoming water supply is sufficient though (this applies to combis also). For unvented, you typically require a 20 l/m flow rate and 1.5 bar dynamic (working) pressure, as a minimum.
    • Grenage
    • By Grenage 19th Apr 17, 3:24 PM
    • 1,145 Posts
    • 1,067 Thanks
    Grenage
    We (2 adults) were happy with a 24kw combi at the last place; the shower was a thermostatic mixer, and there was always enough hot water at the taps.

    Our new home has a 20-yr old Potterton, with a power shower; I'm never going back to a combi.
    • prosaver
    • By prosaver 19th Apr 17, 3:58 PM
    • 6,457 Posts
    • 5,005 Thanks
    prosaver
    mine like this


    waiting for it too conk out, had it repaired twice, 90 and 60 pounds in 20 years .
    Still going stong tho.
    think its from the 70's
    retro and all that
    “Life isn't about finding yourself. Life is about creating yourself.”
    ― George Bernard Shaw
    • Chanes
    • By Chanes 19th Apr 17, 7:46 PM
    • 841 Posts
    • 522 Thanks
    Chanes
    We replaced a cylinder heater and central heating boiler with a Vaillant Ecotec pro 28 it has been a far most cost effective system to run and has reduced the heating bills and freed up the closet which housed the cylinder and space in the loft which the tank occupied.
    • coffeehound
    • By coffeehound 19th Apr 17, 8:24 PM
    • 1,074 Posts
    • 1,766 Thanks
    coffeehound
    Fortunately it used to reach the melting point of solder before the pressure was sufficient to rupture the heat exchanger, so it usually failed by slipping one of the joints. Nevertheless, it was still a big bang followed by a kitchen full of scalding steam then a flood of water. <snip>
    Originally posted by jack_pott
    Thanks that's useful to know. Must've been a nightmare to have to put up with all that time. If PRVs aren't mandatory on unvented heating/water circuits now, your experience there makes a very strong case for them.

    .
    Last edited by coffeehound; 19-04-2017 at 8:28 PM.
    • katejo
    • By katejo 19th Apr 17, 10:08 PM
    • 2,942 Posts
    • 1,122 Thanks
    katejo
    a plumber told me combi dont last as long as the other, too many parts or something
    Originally posted by prosaver
    My Vaillant combi is now about 14 years old and still going strong. Has just been serviced and is still in good working order. Only 1 repair in the 11 years that I have been here and that was about 3-4 years ago and cost about £300.
    • Kernel Sanders
    • By Kernel Sanders 20th Apr 17, 12:13 PM
    • 3,055 Posts
    • 1,271 Thanks
    Kernel Sanders
    Same for a combi.
    Originally posted by fezster
    I was talking about combies!
    Having had an unvented setup, I'd definitely prefer that, unless space prohibited me from having one.
    Originally posted by fezster
    But unvented systems take up less room!
    • fezster
    • By fezster 21st Apr 17, 9:27 AM
    • 166 Posts
    • 83 Thanks
    fezster
    I was talking about combies!

    Originally Posted by Kernel Sanders View Post
    Nobody seems to have mentioned the Achilles' Heel that unvented systems have;
    <snip>
    you'll be able to flush your toilet just the once, have no hot water to wash your hands afterwards and no cold to even make a cup of tea.
    Originally posted by Kernel Sanders
    You said unvented, though. Combi's and unvented cylinders are both mains pressure driven so equally affected by what you described.

    But unvented systems take up less room!
    Not sure how you arrived at this conclusion. A combi boiler may be slightly larger than a conventional boiler (depends on brand and model), but an unvented cylinder requires space for an *entire* cylinder on top of that!.
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