heating advice sought after.....please

Discussion in 'Plumbers' Talk' started by bebradi, Nov 7, 2003.

  1. bebradi

    bebradi New Member

    Hi,
    I have a very old house, with no central heating. We are planning to install a Rayburn which will heat the water, and supply heat for the radiators "which we still have to install".
    In the research I have made, I now know most of it, but am stuck on a few questions and would appreciate very much any help, the queries are as follows :-
    1) I will be replacing the old immersion (with it's header tank built in) with a new modern 26 gallon, and I need a header tank in the loft for it...so basically, what capacity tank should I use ? and can I combine the radiator headertank "which I have to install also"?
    2) Could I have 2 immersions on the loop ?
    3) I know that on the heating circuit, a couple of radiators should be left open and should have 15mm piping, but what about the rest of the house, can I get away with 10mm ?
    Thanks in advance for your time
     
  2. bebradi

    bebradi New Member

    Please help, any advice greatly received and appreciated
     
  3. supersparky

    supersparky New Member

    im not a plumber but, i would say go for the biggest tank you can for cold water storage (for the central heating you only need the 4 gallon one)
    one thing i can tell you for sure that if you have two imersion heaters you will have to have two circuits if they are 3kw ones, 3kw immersion heater is 13amps so two would be 26 amps....a little high for a 16amp breaker.
    dont know about number 3 so i wont even guess.
    Hope that helps

    BR
     
  4. bebradi

    bebradi New Member

    Hi Supersparky,
    Thanks for your help. With the immersion heaters, I only plan to wire in one immersion element, with the other one connected by the coil element connected to the rayburn.
    All our cold water is directly connected to the mains water, so in effect the header tank or tanks will only suppy the immersion and radiator topup's.
    So basically, would I get away with say 25 gallon tank and connect the immersion and the central heating topup to it, or can I get away with two 4 gallon tanks "or even one 4 gallon tank for both
     
  5. chtechie

    chtechie Member

  6. supersparky

    supersparky New Member

    i wouldent think you could get away with just 4 gallons......would have thaught one of the plummbers would give you advise on that if the site dont help.and aslong as the two imersions are not on the same breaker your fine....but not many people use two imersion heaters anymore...or so it seems

    BR

    Btw chtecie can you recomend a small combi, ive herd that ravenheat are sh*te, so that idea fell through...
     
  7. bebradi

    bebradi New Member

    I'll take a look, thanks Chtechie
     
  8. sabres

    sabres New Member

    A note of caution. I have lived with a rayburn powered central heating system for 6 years from new and it has proved nothing but trouble. Constant breakdowns and parts needing replacing. Whilst great for cooking and hot water it doesn't appear to be up to the rigours of supplying heating. It is due to be ripped out and replaced next year.
     
  9. the grim emailer

    the grim emailer New Member

    What type of fuel will you be using in the Rayburn please?
     
  10. bebradi

    bebradi New Member

    Hi Sabres and the grim emailer, Thanks for your replies..
    With the system that I have, nothing to major can go wrong "One hopes". The fuel intention is mainly "95%" going to be coal(anthracite).
     
  11. Deelow

    Deelow New Member

    I believe that you should always have separate tanks for each service. A small dedicated boiler header tank to which the expansion overflow pipe will feed boiler cicuit water back into through a swan neck return pipe. You wouldn't want that sirty water to mix with your cold feed water supply to your hot tank. Especially if you pour Corrosion Inhibitor into the boiler header tank. The maximum size for the cold supply tank would be approx the size of your Hot (Immersion heated) cylinder capacity as a minimum to save you running dry.
     
  12. bilco

    bilco New Member

    Hi bebradi
    1)4 gallon header tank...this supplies the water in the heating circuit...25 min gall cold water feed tank to supply hot water through the cylinder.(you can't combine them0
    2)you can have two hot water cylinders...if this is because your requirements for hot water are far away from each other...it may be better to install a "secondary return" for the furthest one.
    3)Yes. The "always on" rads need to be connected so heat circulates without the pump running.
    Hope that helps if you would like more post your em
     
  13. bebradi

    bebradi New Member

    Hi Bilco and Deelow and everyone who has helped me so far, thanks for your help.
    With the idea of two immersion tanks, the theory of it is this.....I have both tanks available and instead of scrapping the old one, I had the idea of placing them side by side, one slightly lower than the other, because basically trying to maximize everything (the electric element will only be connected to one).. With this idea I am worried that it then might not be efficient to heat up at least 8 radiators and two tanks. It sounds good in theory, but not sure in practice..
    The other query I have is 10mm or 15mm or a combination of both ? ie... 15mm to the open radiators and 10mm pumped around for the rest.
     
  14. bilco

    bilco New Member

    Hi bebradi
    It is for all practical purposes not possible to use your old combination cylinder (the reasons are many and difficult to relate here) suffice to say your new installation requires two separate water systems:-
    The water in your Rayburn, radiators and cylinder coil does not change and is used as the medium to transfer heat indirectly to the air by heating the rads and the water by heating a coil inside the cylinder. The water level is maintained by incorporating the 4 gallon header tank as high as possible above the highest rad to minimise air ingress through the function of the pump (circulator).
    The water in the cylinder that supplies your taps is fed from a 25 gallon min. cold water feed tank positioned as high as practical to give the optimum flow rate to your taps.
    The pipework to the non pumped rads, depending on length and bends should be at least 15mm but may need to be larger...the pipework to the other rads can be micro-bore (10 - 8mm) with the manifolds fed by 22mm nominally. Rayburns have two 1" tappings so you will need to use an injector tee on the return.
    If you use micro=bore pipes you should add an inhibitor to the system to minimise sludge build-up.
    It is advisable to fit a cylinder stat that closes on rise in temperature...then when your hot water is at the desired temperature the pump is switched on, overriding any other controls, thus avoiding excessive water temperatures in your boiler.
    I hope that helps...as before if you post your E.M. addy up I can more easily respond
     

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