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change to unvented or dont bother?

Discussion in 'Plumbing and Central Heating' started by psychonaut, 20 Aug 2016.

  1. psychonaut

    psychonaut

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    hi everyone, hope you are well.

    we've moved into a new house in april.

    it has a vented system. cylinder is pretty old, has minimal insulation but it works fine. its quite small but we havent run out of hot water yet. i have the hot water on for about 3 hours a day.

    we have had the central heating off since may, so barring cooking i know what the hot water costs are - about 50p per day for 2 or 3 long showers and a (half full) bath for the kids

    house is as follows:

    bathroom 1 - with an excellent, if noisy, pumped shower and will add an actual bath at some stage

    bathroom 2 - 1 bath and a rubbish electric non-pumped shower ..mainly used for baths so not a big deal with the shower

    ensuite - shower with excellent pumped shower

    we are 2 adults, one 2.5 yr old and a 7 month old baby

    pressure is 3.5 bar standing, 2.5 bar working

    i was always thinking to get it changed for an unvented system. (megaflow or whatever).

    however, im wondering if its worth it. the showers that we use are great. if they build more houses, maybe the pressure will drop. the bath takes ages to fill, but its not a huge problem.

    thought please?
     
    Last edited: 20 Aug 2016
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  3. algas

    algas

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    If you have money to throw away change it, but if it isn't broken don't try to fix it
     
  4. psychonaut

    psychonaut

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    agreed, if it aint broke...

    well, ive got a budget to do the house...but i have lots of other things to spend out on the house as its old, so im thinking it could be better used elsewhere ....


    are there any benefits to unvented?
    i could change the cylinder for a more modern / better vented cylinder? will that save me much money?

    insulate the existing one?


    i was also thinking to get solar water heating, but given the 50p per day heating costs for water, im not convinced its worth bothering
     
    Last edited: 20 Aug 2016
  5. bernardgreen

    bernardgreen

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    The only bebefit I have heard on this forum is the there is no header tank for animals to drown in. ( A lid on the tank prevents this )

    It is true that a non-vented tank can give more pressure to the water coming out of hot taps. But too much pressure means high velocity water out of the tap which can then splash ut of the basin.

    The dis-advantages of non vented are ( among others )

    1) the need to have an annual safety check of the over pressure relief valve(s) and the safety drain piping

    2) a failed pressure reducing valve on the supply to the cylinder can raise the pressure in the cylinder high enough to open the pressure relief valve and dump all the hot water and then the boiler fires up to heat the fresh cold water flowing into the cylinder and then out of the pressure relief valve(s).
     
  6. psychonaut

    psychonaut

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    ok. is there anything i can do with my unvented system that will make it better? tank insulation would seem a good idea...any pointers on that?
     
  7. bernardgreen

    bernardgreen

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    Is it an un-vented radiator system with a vented hot water cylinder ?
     
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  9. psychonaut

    psychonaut

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    sorry - i meant exiting system is vented.

    i'll edit my posts....thanks for pointing that out!!
     
  10. psychonaut

    psychonaut

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    thats a good point though. the radiator heating is vented too. any advantages /disadvantagesin getting this pressurized?

    can i have a pressurised radiator system, and a non pressurised hot water system?
     
  11. Hugh Jaleak

    Hugh Jaleak

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    From what I've read, I'd change the cylinder for a new, better insulated version, with fast recovery. Check the cisterns in the loft, fit correct lids and insulation as required. Heating system, biggest disadvantage with pressurising an existing older system is, the higher internal pressures will find any weak spots and possibly cause it to start leaking.

    Personally I'm in the 'if it aint broke, don't fix it' camp, but that's not to say a few £ upgrading what you have may be money well spent. What type of heating system is fitted? Upgrading the system and/or controls can also often be money well spent, and lastly, check your insulation levels. Cheap to top up if required and soon pays for itself.
     
  12. dilalio

    dilalio

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    If this is something you might want to do in the future, then it might be worth considering putting the necessary services in the building fabric (pipes, cables etc) before you button each room up with nice new decor, kitchens and bathrooms etc. That way, it's all there for you to hook up to without ripping finished rooms, floors and ceilings to pieces!
     
  13. psychonaut

    psychonaut

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    thanks again...more questions then....

    loft cisterns - i hadnt even thought of that. we have 2 (one big for the water and one small for the heating?) the small one is barely above the height of the rads upstairs. no idea what kind of insulation they have but i will check.

    any advantages to pressurized radiators?

    can i pressurize rads and not hot water?

    loft insulation is already on the list of the many many things to do!

    as for what kind of heating system - theres the boiler (british gas 330. it had inhibitor added in 2007, this may also be when it was installed, looks fairly new) , tank, several grundfos valves.

    nearly every rad has a trv on it. there are 21 rads in this house, all without fins. gas bill was £168 the first month we moved in! have since turned them all off. want to replace some of them with modern. will probably leave most of the old style ones off permanently though
     
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