Leaking cylinder, time for a combi boiler?

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quarkyquarky Frets: 2777
edited January 2018 in Off Topic
Great news for a Friday in January, but my cylinder is leaking. It actually does both the HW and the CH so I don't have either at the moment. We have been told that we can replace it with something more conventional, or a combi-boiler.

We have about five bedrooms, three bathrooms, and there are four of us. Two adults, and two kids (10 and 13). And a dog. 

Does anyone have any experience as to whether a combi is going to be OK? I heard that it cause issues if someone flushes the toilet while using the shower, or is filling a sink while someone else is running bath? Not sure if it makes any difference, but we have a bathroom in a loft conversion (so higher than the current cylinder), but don't have any HW radiators up there, only electric..
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  • cj73cj73 Frets: 1003
    A combi is demand based.  No storage tanks so water is heated in 2 circuits as required.  If you've go the heating on and someone runs a hot tap then the heating will  "go off".  Unless your house is mahoosive, really badly insulated or your baths are olympic sized you probably won't notice.   Normal terms and conditions apply etc, etc
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  • cj73cj73 Frets: 1003
    If you don't mind me asking, who told you

    quarky said:
    that we can replace it with something more conventional, or a combi-boiler..


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  • RandallFlaggRandallFlagg Frets: 13929
    We have an Ideal Logic+ Combi, had it fitted 2 years ago. It is generally fine but we do have to run the hot tap for a little while before the hot water comes when the heating is on. It had a preheat function where a small amount of water is held warm but it's not enough to fill up a bowl for washing up so runs cool after that before the really hot water runs, how long depends on how far the tap is away from the boiler. It's using less gas that's for sure and the electronic wi-fi thermostat is good. Came with a 7 year warranty if I keep it serviced each year, the local fitter does it for £40.

    We have 3 bedrooms, a garage conversion and there's 4 in the house. Supply and install with thermostatic valves fitted to all radiators was £2250


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  • quarkyquarky Frets: 2777
    Thanks @cj73, sounds good. Nope, it is a 2000 build house, and had additional insulating put in, so hopefully we will be fine then. Cheers!
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  • quarkyquarky Frets: 2777
    cj73 said:
    If you don't mind me asking, who told you

    quarky said:
    that we can replace it with something more conventional, or a combi-boiler..

    Could be Chinese whispers from the plumber to my wife, then to me!
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  • quarkyquarky Frets: 2777
    We have an Ideal Logic+ Combi, had it fitted 2 years ago. It is generally fine but we do have to run the hot tap for a little while before the hot water comes when the heating is on. It had a preheat function where a small amount of water is held warm but it's not enough to fill up a bowl for washing up so runs cool after that before the really hot water runs, how long depends on how far the tap is away from the boiler. It's using less gas that's for sure and the electronic wi-fi thermostat is good. Came with a 7 year warranty if I keep it serviced each year, the local fitter does it for £40.

    We have 3 bedrooms, a garage conversion and there's 4 in the house. Supply and install with thermostatic valves fitted to all radiators was £2250

    Thanks. That doesn't sound too bad, and I love the idea of a WiFI thermostat!
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  • cj73cj73 Frets: 1003
    quarky said:
    cj73 said:
    If you don't mind me asking, who told you

    quarky said:
    that we can replace it with something more conventional, or a combi-boiler..

    Could be Chinese whispers from the plumber to my wife, then to me!
    Only asking cos my parents had a cylinder fed system in their ancient sandstone semi and it took a right wad to replace, mostly due to the massive pipes and cast iron radiators that that they didn't want to lose.  A 2000 build should be much easier to retrofit a combi though.  As @randallflagg says they are much more efficient over all, especially condensers but then you're looking at putting boiler close to external walls and flue run issues.

    22 years of tech support with BG, can you tell?  
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  • NeilMcGNeilMcG Frets: 62
    My father has a condensing combi in his house. It is good for heating and small amounts of hot water, but it can't fill a sink with really hot water.

    He has an electric shower and no bath, so it is fine for him and is cheaper to run than his old boiler. I'm unconvinced as a general replacement for conventional boilers if large volumes of hot water are wanted.
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  • ZoolooterZoolooter Frets: 886
    Just had an Intergas combi fitted for my dad. Very reliable, used in all the scandi counties and the states. Cheaper than Worcester and valiant - simpler design apparently.
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  • boogiemanboogieman Frets: 12314
    If you’ve got decent mains water pressure it should be fine. Only thing I think you need to check is if any shower is pumped, afaik you can’t have a combo boiler with a pumped shower. 
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  • RandallFlaggRandallFlagg Frets: 13929
    edited January 2018
    NeilMcG said:
    My father has a condensing combi in his house. It is good for heating and small amounts of hot water, but it can't fill a sink with really hot water.

    He has an electric shower and no bath, so it is fine for him and is cheaper to run than his old boiler. I'm unconvinced as a general replacement for conventional boilers if large volumes of hot water are wanted.
    Ours is fine, once it gets heating the water it will just go and go, fills a bath with piping hot water no problem. You just have to run a little cold off until it starts heating


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  • ToneControlToneControl Frets: 11789
    It's a big house, so I bought a large condensing boiler with a heat reservoir. Idea is to have 10 mins of hot water ready, to do 2 showers at once
    Even with that switched off, it fills a bath in 14 mins along pipes that  I now know are too narrow.
    Since both showers are on same pipe, theory does not work in practice. I could double up pipes, but ....

    In retrospect, I would buy 2 normal condensing combi boilers, each serving a separate bathroom and half the radiators each.
    That way, you will never be without hot water and heating (unless there is a power cut or a zombie apocalypse)

    This is DR provision (IT guys know what I mean)
    In my last house, we had no boiler for 2 weeks, due to an inept contract maintenance repair company. Not nice
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  • WezVWezV Frets: 16542
     ours takes a little while to give  hot water if the heating is on, but once it’s going it’s fine.  

    The shower slows down when someone uses another tap, but doesn’t get colder. It’s annoying but not terrible like being drenched with cold water unexpectedly  


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  • ToneControlToneControl Frets: 11789
    NeilMcG said:
    My father has a condensing combi in his house. It is good for heating and small amounts of hot water, but it can't fill a sink with really hot water.

    He has an electric shower and no bath, so it is fine for him and is cheaper to run than his old boiler. I'm unconvinced as a general replacement for conventional boilers if large volumes of hot water are wanted.
    mine drives a shower like a power shower would
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  • quarkyquarky Frets: 2777
    boogieman said:
    If you’ve got decent mains water pressure it should be fine. Only thing I think you need to check is if any shower is pumped, afaik you can’t have a combo boiler with a pumped shower. 
    Thanks, we do have really high pressure so hopefully it will work out.
    Zoolooter said:
    Just had an Intergas combi fitted for my dad. Very reliable, used in all the scandi counties and the states. Cheaper than Worcester and valiant - simpler design apparently.
    I think Worcester and Valiant at the ones we are going to be quoted for. They are good according to plumber, so we will see what the quotes are like. 

    At least it isn't freezing so there won't be any Lawrence Oates moments over the next few days I hope :)


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  • HAL9000HAL9000 Frets: 9550
    quarky said:

    We have about five bedrooms....
    About? Aren’t you sure?

    Seriously though, the problem with no storage tanks is that if the boiler fails (which will only ever happen in the dead of winter) then there is no heating or hot water. We opted for what, if I remember correctly, is called a system boiler. Essentially it lets you keep a hot water tank with an immersion heater so that you can at least always get hot water.
    I play guitar because I enjoy it rather than because I’m any good at it
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  • quarkyquarky Frets: 2777
    HAL9000 said:
    quarky said:

    We have about five bedrooms....
    About? Aren’t you sure?

    Seriously though, the problem with no storage tanks is that if the boiler fails (which will only ever happen in the dead of winter) then there is no heating or hot water. We opted for what, if I remember correctly, is called a system boiler. Essentially it lets you keep a hot water tank with an immersion heater so that you can at least always get hot water.
    Yeah, it depends on definitions. For insurance purposes, five and a study. Same for practical purposes too be honest, until I decide to sell!

    I do have shower that is heated separately, so at least we can have a shower over the next days, even if there is no heating or other hot water. I could this again when *this* boiler fails in the future I guess. I think a system boiler might be like the other option he proposed. 
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  • ICBMICBM Frets: 71953
    I have never been in a house with any kind of on-demand water heating that works as well as one with a good old-fashioned gravity fed hot water tank system.

    If you’ve got a tank system and the tank is leaking, just replace the tank - it’s both the easiest and the best solution.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • exocetexocet Frets: 1948
    If you currently have a HW tank then personally stick with a conventional setup ie not a combi. Assuming that your current tank is in an “airing cupboard” - you’d miss that facility if you replaced with a combi.
    Combis can struggle to provide enough HW on demand - especially during cold spells when they need to heat up colder water. The heat reserve type are pretty effective but for a 5 bed house the appropriate Worcester combi is floor standing and the size of a washing machine. Combis are also only suitable where you have decent mains water pressure eg 1.5 Bar and upwards.
    The final nail in the coffin for me is reliability - they are not as reliable as a conventional setup so if you do go down that route, stick to Worcester or Vaillant. I’ve had two houses and fitted two standard  Vaillant boilers over a 22 year period. Never had a service contract on either and neither ever let me down. 
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  • axisusaxisus Frets: 28280
    quarky said:
    We have about five bedrooms, three bathrooms, and there are four of us. Two adults, and two kids
    Wow, how the other half live! We have 2 and a half bedrooms, 1 bathroom and there's 6 of us! 
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