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System or Normal Boiler replacement

Discussion in 'Plumbing and Central Heating' started by wbjimmy1, 19 Jul 2021.

  1. wbjimmy1

    wbjimmy1

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    I am considering replacing my existing Vaillant thermocompact (non-condensing) system boiler principally because it is now 16 yr old. It’s currently part of an indirect, unvented, Y plan set- up comprising a vented indirect hot water cylinder ( in the airing cupboard) and a cold water tank ( minus expansion/header tank) in the loft. I also had to connect a separate external expansion tank a couple of years ago when the internal one failed. The original header/expansion tank was removed from the loft together with the pump when it was installed to replace the original fit Potterton Netaheat.
    My question is should I just replace it with another system boiler or, recognising that I still have a cold water tank in the loft could I replace it (and at lower cost ?) with a normal boiler and external pump?
     
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  3. ianmcd

    ianmcd

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    By "normal" boiler, do you mean a heat only boiler ?
     
  4. wbjimmy1

    wbjimmy1

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    Yes. I’ve ruled out a combi because we have 4 bedrooms and have more than 1 bathroom. Everything I have read suggests a main advantage of system boilers is you don’t need a cold water tank in the loft -but I still have one hence the question why I need a system boiler - or could I get rid the cold water water tank?
     
  5. Mottie

    Mottie

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    I understand that having separate an external expansion cylinder and pump etc can make it easier and cheaper to repair if needed. I’m sure I’ll be corrected if that’s wrong.
     
  6. sxturbo

    sxturbo

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    It's neither here nor their on cost really.

    Other than with a system boiler you get a bigger warranty and more parts are covered under that warranty.

    You buy a new pump from grundfos and it's highly unlikely to have a 10 year warranty..
     
  7. Can you move over you the car section please .... I'll deal with this.. :D
     
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  8. To have no tanks in your loft you would need an unvented cylinder as well. A system boiler won't do it all alone...

    But it's the way to go.....
     
  9. CBW

    CBW

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    You don’t need a cold water storage cistern for the heating if you have a system boiler, but you still need one for the hot water. As per Bodd, if you want zero tanks in the loft then you’d need an unvented cylinder (which you stated in OP as having) and system boiler.
     
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  11. wbjimmy1

    wbjimmy1

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    Understood. Thanks for advice. As my hot water pressure is OK and Im not planning on a loft conversion anytime soon so I think I’ll stick with my loft tank and vented cylinder and save the additional expense of upgrading to an unvented one. As for the boiler, it seems there is little to gain in either performance or total cost by installing a heat-only model and adding a separate pump instead of replacing it with another system boiler. But I’ll get my plumber to quote for both.
     
  12. sxturbo

    sxturbo

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    Exactly that.
     
  13. MeldrewsMate

    MeldrewsMate

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    In a quirk of the marketting strategy, most manufacturer's combi boilers are cheaper than their system boilers, even though there are more bits in a combi. A combi is a system boiler plus extras, and the heating output from a combi can be used directly in place of a system boiler...in many cases the combi uses the same backplate as the system boiler, so an easy swap. Dependant on the model you choose (obviously one made in the UK) you may have to provide a mains water connection, though in just about all cases the combi's hot water output can be sealed off without detriment.

    There is only one fly in the ointment; any combi boiler must comply with the Boiler Plus regs, so must have one (or more) of four energy saving options to be compliant. If you're open to the idea of Nest/Hive or load/weather compensation then that problem goes away.....if you kept a Netaheat running in the past 20 years then my suspiscion is that you're not!
     
  14. DP

    DP

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    A good boiler getting replaced at 16 years when some at 30 years still giving great service makes no sense.
    What would be prudent is proper service and better controls
     
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  15. wbjimmy1

    wbjimmy1

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    I must admit I too have doubts about the need to replace a 16yr old boiler which has been annually serviced and had fresh CH protector added every 2yrs. Apart from a failed expansion vessel it has never let me down and as the last of the non-condensing type it is almost as efficient as the current condensing models (p.s. it’s a Valliant thermocompact not the Netaheat it replaced). But Valliant will no longer service it and I had difficulty this year finding a local plumber willing to do it. Perhaps someone can tell me if getting spare parts for these older boilers is likely to be problem and what the expected life of the pump is?
     
  16. DP

    DP

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    I was servicing a boiler last week that is 30 years old
    Original pump that has lost its power a wee bit, hence will need replacing ( not entirely true as a component within can be replaced to restore full power to the motor)
    Most parts are available apart from rarely needed ones.
    Within these pages and combustion chamber, there are chaps who provide sterling service and are familiar with valiant range
    What will destroy any boiler is lack of manufacturer recommended regular service.
    Expansion vessels do fail but that does not mean it is nail in the coffin for the boiler

    Couple of weeks ago replaced a Vaillant Sine 18. Now that is a boiler that was built like a brick outhouse. Was replaced as part required is no longer available. Boiler easily over 30 years old. Same pump still functioned but external expansion vessel fitted as internal had failed

    what is you location
     
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  17. fixitflav

    fixitflav

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    If you feel you must change the boiler I would go for a heat-only. You already have an external expansion vessel, and with pump and boiler separate it's easier to diagnose and fix any problems.
     
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