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Which type of boiler and system for our situation....

Discussion in 'Plumbing and Central Heating' started by abbadon, 7 Feb 2011.

  1. abbadon

    abbadon

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    Please bear with me for a short while, as I try and explain what's afoot..

    My mothers property is a large house, which has currently got a rayburn range doing both heating and hot water. However this unit has 2 problems...

    1. it isn't really quite big enough, since the property has been extended since it was installed. (Property has I think 17 radiators now, and might well rise to 19 or 20 with some changes required...)

    2. it sprung a leak before Christmas and has a slow drip internally now, not causing an issue right now but will surely get worse in the future.

    With the above things in mind, the plans was as follows:

    Have the range converted to cooking only (it has bee suggested this can be done by putting sand in the heat exchanger, disconnecting the water obviously, or by replacing the exchanger with fire bricks filling it up so it becomes basically a giant storage heater.)

    And having a modern boiler installed.

    The grand pla is mum to run a b and b, with 2 rooms to begin with, rising to 3 rooms maybe 4 in due course.

    Initially there will be 2 rooms each with a dedicated bathroom with showers etc..., later it will probably be 3 rooms with a shower each, a 4th room would only be added as an additional bed space for children, linked to one of the other rooms and share their bathroom.

    The house already has another bathroom linked to my mothers room.

    We had been erring towards a large 40+ Kw combi, but we have started to doubt this is the right way to go, even though it would seem that a combin with 25l capability would be good to run 3 showers simultaneous, it seems this is doubtful to work even though our water pressure seems to be pretty good.

    What I would like is advice on what sort of boiler and system would be best, sizing for water tank - type of tank and any other advice!

    I can of course supply more info to assist with this!

    cheers

    Andy

    Extra background:

    The current rayburn i think is only really capable of supplying around 11 rads or so, but just about copes with getting the house warm on a good day, but doesnt d it fast enough really. I think its total output is 20kw t hot water (CH plus cylinder) and its total heat input is 30kw to water and cooking areas.
     
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  3. abbadon

    abbadon

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    Anyone offer us some advice - we have a plumber on hold from ordering boiler etc..!
     
  4. Tibbot

    Tibbot

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    You have a plumber who's awaiting technical instruction from you, the punter, who in turn is awaiting advice from strangers on the web? This trade gets more ****ed up every day.
     
  5. abbadon

    abbadon

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    What I could really do with is a plumber in our area who can offer us the correct testing, advice and know how to spec what is really required..

    We have had a man from the gas board, and 2 independents, both of which came recommended on their past work from a very good friend.

    Its frustrating that none of the above 3 tested in any way that water pressure/flow is good enough, nor knew that really for our application the combi probably isn't suitable.

    I am at a loss - I am schooled in mechanical engineering, but don't really have the time to spend reading and determining everything to know what to buy, and even then finding someone who will agree to fit it all :S

    Andy
     
  6. abbadon

    abbadon

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    We now know that we have 3.8 bar mains pressure at the outside tap.

    Does this sound sufficient to provide enough pressure for a high flow combi?


    Can anyone also tell me whether or not a thermal store suffers as badly from multiple outlets being open at a time as do combis?

    AB
     
  7. Agile

    Agile

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    I suppose you are expecting these three to come along, measure water and give you a fully detailed specification all for FREE !

    You could then hawk it around to the East European plumbers until someone installed it for you for £138.

    If you are a mechanical engineer then presumably you will have taken "A" level physics and thus should realise that water pressure is not very important for your showers.

    Tony


    PS Note that the Viessmann boiler mentioned above will only give about 12 li/min after the store has been exhausted.
     
  8. namsag

    namsag

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    Combi no matter how big is the last thing you want for what you are planning .
     
  9. danhiltonplumbingservices

    danhiltonplumbingservices

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    you need to start looking into unvented heating massive tank 1 huge boiler or 2 smaller ones and if its a large house even a hotwater return pipe to stop deadlegs i could go into detail but i wont cause i think you should get a real plumber to look at your house and decide what to get. you have issues with roomstats in each room etc ( i have done about 20 of these size jobs all for people making houses to b and bs)
     
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  11. ALEC1

    ALEC1

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    Agile is correct but he misses a point....

    rarely, indeed if ever, are all hot taps opened simultaneously.

    This boiler reheats to usable temperature in about 10 minutes

    it would enable you to fill two average baths, and run a shower there after continuously.

    The argument for this is energy efficiency/savings. Big cylinders are fine and do guarantee a big supply, but they do loose heat...
     
  12. algas

    algas

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    But when the combi goes tits up & you know it will! if you have a storage cylinder with immersion back up this will hold the fort untill the cavalry arrive :D
     
  13. vv2806

    vv2806

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    Tony, are the customers supposed to agree for a new system to be installed without knowing any specifications? Or perhaps they have to pay to be given a quotation?

    The OP hasn't asked about DETAILED specifications, he asked whether a combi boiler is a good idea or not and how big the tank should be. A decent plumber/gas engineer should be able to advise him. As for the East European plumbers, if they are able to do the work, they would be probably able to design the system as well. And any plumber - East European, African, or British, shouldn't be allowed to do the work, if they are not able to design the system.
     
  14. xr4x4

    xr4x4

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    ditto
     
  15. mysteryman

    mysteryman

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    The boiler I mentioned above has a 130 litre store, and reheat starts as soon as you open a hot tap. You would need to be very determined to run it cold.
     
  16. namsag

    namsag

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    What even if the water main could supply enough water to supply possibly 4 showers and a hot tap going at the same time,Dont talk nonsense
     
  17. mickyg

    mickyg

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    i thought thats what sales reps were born to do? :D
     
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