Unvented system Vs Combi

Discussion in 'Plumbers' Talk' started by TallPaul, Feb 23, 2010.

  1. TallPaul

    TallPaul New Member

    Evening,
    Currently I have an old Combi boiler system. I'd like to fit a new bathroom with a thermostatic shower. I have 7 rads, one bathroom.
    Question.. Is an unvented system more or less efficient than a good, new combi boiler.

    I have room to install a cylinder next to the boiler, in the cellar.
    I've also thought about having solar panels to heat the water. I know I need a cylinder for this.
     
  2. G Brown.

    G Brown. New Member

    how many people in the house.
     
  3. Tony Soprano

    Tony Soprano New Member

    combi boiler is an item which tries to do everything in one neat box,unfortunately they do have their limitations

    With an unvented cylinder coupled to solar you can get a certain percentage of your hot water absolutely free and power shower performance

    Absolutely no contest between unvented and combi,the cylinder wins hands down
     
  4. TallPaul

    TallPaul New Member

    At the moment just me. Sad, but true.
     
  5. TallPaul

    TallPaul New Member

    The solar panel thing is a nice to have item. Need to cost it up.
    How much would I be looking at to install an unvented system. Like I say, everything is easy to get at in the celar.
     
  6. TallPaul

    TallPaul New Member

    Whoops! That should be cellar
     
  7. Captain Leaky

    Captain Leaky New Member

    Much as I detest combi's if you are on your own then you are probably better off with a combi.
     
  8. G Brown.

    G Brown. New Member

    Tony is right about unvented winning hands down, but you asked which is the most efficient, if you live on your todd then combi it is.
     
  9. imran_

    imran_ New Member

    An unvented is just as efficient as a combi, probably moreso. However overkill for one bathroom usually, and I'd NEVER recommend fitting solar - not now anyway.
     
  10. Tony Soprano

    Tony Soprano New Member

    I recommend and install solar and plenty of it,if planned correctly and installed properly it is the best of all the renewables available today

    Also in the new build market,where they have to use a certain amount of renewable technology certain councils are letting planning go through alot easier if solar is used
     
  11. G Brown.

    G Brown. New Member

    Explain Imran how stored water is more effecient than a combi for a household of 1.
     
  12. imran_

    imran_ New Member

    Where to start...
    1. A combi will be 30kw+ for a decent shower, so usually is oversized, condensing for less time and low mods to a higher figure than a smaller boiler
    2. A combi fires on demand (boiler cycling), an unvented may need the boiler to be fired only once per day (at the same time as heating)
    etc, etc, etc, - there are lots of arguments

    I know where you're coming from - storing water is inefficient..... But an unvented loses less than 2kwh per 24 hours, that's 7p of gas or combi cycling for 4 mins a day.

    The stored water of old days is highly inefficient. Today its not true. In terms of cost and space a combi is the best bet. But not necessarily for fuel efficiency.

    IMHO, I welcome other opinions!
     
  13. imran_

    imran_ New Member

    As for solar, there's no reasonable payback time. GSHP, ASHP, photo-voltaic panels all better. It will take 15 yaers to payback on solar, better to pay your mortgage off!
     
  14. Tony Soprano

    Tony Soprano New Member

    As for solar, there's no reasonable payback time. GSHP, ASHP, photo-voltaic panels all better. It will take 15 yaers to payback on solar, better to pay your mortgage off!



    biggest load of nonsense written!!!

    The cylinder,has to be upgraded,how much extra?

    the boiler will be same for new install

    the extra part of the install is the panels and connecting to the heating system
    The rest of the system is as normal new install

    where did you work this out it will take 15 years and how much is your mortagage wish it was the price of solar install!!!
     
  15. Dick Puller

    Dick Puller New Member

    I recommend and install solar and plenty of it,if planned correctly and installed properly it is the best of all the renewables available today..................................100% agree with you there Tony, solar is the cheapest install price & the best for saving fuel!!
     
  16. Dick Puller

    Dick Puller New Member

    At the moment just me. Sad, but true..................................Get down the Park with a wean in a pushchair SadoPaul, the birds will be all over you. A pushchair is a better pussypuller than a Sports car!!

    By the way, she's not going to be too impressed with your new boiler son, just your trouser snake.
     
  17. imran_

    imran_ New Member

    To clarify: I always install dual coil cyls for future proofing but not recommend solar panels yet. Right now they'll only shave around 15% of your energy bill, and that's a poor ROI.

    The smart money is on photovoltaic cells, and if you install solar there may be no room for that as well. PV is currently too expensive, but in less than 5 years time will have a good ROI plus you get a ridiculously high feed-in tariff as already outlined by the govt.

    That said I would recommend solar for heat banks/thermal stores (not that I install many at the mo) as the energy produced can be used for the heating as well as hot water, especially suited for UFH.

    The govt is going to launch a massive subsidy next year for solar, but only for MCS installed systems. See http://www.guardian.co.uk/money/2010/feb/20/solar-water-heating-incentives for details and some of the small print. Once this is launched solar is a no-brainer and you'd be stupid NOT to install it. Until then you'd be stupid TO.

    IMHO ;)
     
  18. Red White and Blue

    Red White and Blue New Member

    The smart money is on photovoltaic cells, and if you
    install solar there may be no room for that as well.
    PV is currently too expensive, but in less than 5
    years time will have a good ROI plus you get a
    ridiculously high feed-in tariff as already outlined
    by the govt.


    Even with the feed in tarrif which, Could see you receive £1000 per year and potentially half your electricity usage, PV still has a payback period of 12 Yrs + for a good quality install.

    Bearing in mind the PV panels efficiency degrade exponentially with time and have a life span UP TOO 25yrs for a high quality install.

    That said I would recommend solar for heat
    banks/thermal stores (not that I install many at the
    mo) as the energy produced can be used for the
    heating as well as hot water, especially suited for
    UFH.


    SOLAR HOT WATER should never and has never been designed for thermal stores/heatbank due to the high storage temps for domestic hot water.

    The govt is going to launch a massive subsidy next
    year for solar, but only for MCS installed systems.
    See


    On 1st February 2010, the Government published a consultation on the proposed design of the Renewable Heat Incentive (RHI) scheme, which it aims to introduce in April 2011. The consultation seek views on a number of aspects of the proposed scheme, including tariff levels.

    Yeah and that's going to come about after the election when all the countrys debt is to be paid for. Do you live in lala land.

    http://www.guardian.co.uk/money/2010/feb/20/solar-wate
    r-heating-incentives for details and some of the
    small print. Once this is launched solar is a
    no-brainer and you'd be stupid NOT to install it.
    Until then you'd be stupid TO.



    And what does a baldy * columnist know about the installation of renewables, no more than the * that comes out some government ministers or technical advisors mouth.

    Or the * that comes out imrans mouth, it is plainly obvious you have had no proper training or have fitted any renewable technologies.

    Please refrain from talking about technologies you clearly are not qualified to talk about!

    Solar is the most cost effective renewable and will be for the foreseeable future. END OF!

    [Edited by: admin]
     
  19. Water Systems

    Water Systems New Member

    Absolutely no contest between unvented and combi,the
    cylinder wins hands down


    You don't know what you are taking about.Look at a 51kW ATAG. No contest.

    The OP say he can only put a cylinder in a basement. You can't put unvented cylinders in basement as the discharge pipe runs uphill (a no, no). UV cylinders can go kaboooooooom!
     
  20. Water Systems

    Water Systems New Member

    An unvented is just as efficient as a combi, probably
    moreso.


    Imran, you must stop making things up.
     

Share This Page