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Discuss Replacing hot water cylinder on solid fuel boiler in the Oil and Solid Fuel Forum area at UKPlumbersForums.co.uk.

  1. SmokeyJ

    SmokeyJ GSR

    Hi all,
    Looking for some advice.
    A friends dad needs a new hot water cylinder. Easy enough, so i thought.
    Cylinder is fed from a wood burner and has gravity primaries.
    I'm not 'Heatas' and tbh not sure i need to be to carry out the replacement? I am gas safe, oftec and have unvented.
    Thought i'd check the stoves MI's rather than just slapping in a new cylinder, like for like.
    It says a tempreature relief valve should be installed due to the uncontrolled heat source. Makes sense to have one as you could potentially boil the cwsc aswell.
    Is this generally a rule of thumb with solid fuel?

    20180711_190723.jpg
     
  2. Ric2013

    Ric2013 Plumber

    If the system is existing, and the occupants have experience with it, then I'd be less concerned with making the system more compliant than it already is than if it were a new occupant.

    Back to your question. HETAS is just ONE OF the competent person schemes for solid fuel. If you aren't a competent person, then it's a Building Control matter, and do they require notification of a like-for-like replacement of a cylinder?

    I've never heard of this being done, and I used to houseshare with a HETAS training person. It is usual to put a heat-leak radiator on the primaries, however, to keep the primary circuit below boiling. Did this as an upgrade to an existing setup last autumn and, during the snows of this winter I got a text saying 'I've had the fire alight all day and not had to run the hot water off: thank you'.
     
  3. Best

    Best Trusted Plumber

    Just beware that you need a cylinder that has a coil inside it suitable for gravity circulation! Check that with your merchant and also with the cylinder manufacturer to confirm before you order the cylinder. A cylinder for pumped system is no use due to coil having no gradual rise.
    Most solid fuel boilers require a heat leak and thermostatic control for the pump. The pipe stat fitted on return pipe close to the cylinder is essential because it can be too slow at switching on if near boiler
     
  4. chris watkins

    chris watkins Plumber

    The requirement for the temperature relief actually comes from Part G it was added in the update when it stopped being G3 - unvented & evergreen.

    In the Secretary of State’s view Requirement G3(3) will be met for a hot water storage system that has a vented storage vessel if:

    1. the storage vessel has a suitable vent pipe connecting the top of the vessel to a point open to the atmosphere above the level of the water in the cold water storage cistern and over it; and,
    2. in addition to any thermostat, either the heat source, or the storage vessel is fitted with a device that will prevent the temperature of the stored water at any time exceeding 100 ̊C; and
    3. the hot water system has pipework that incorporates a provision for the discharge of hot water from the safety devices to an appropriate place open to the atmosphere where it will cause no danger to persons in or about the building.
     
    • Useful Useful x 1
  5. SmokeyJ

    SmokeyJ GSR

    Hi, thanks for replies.
    I was aware of the gravity coil, some people said a normal one would work but I wouldn't want to take that chance. It was just the relief valve that threw me a bit. Its an easy one to get the discharge out so no probs in fitting one.
    The stove leaked last winter and was replaced. The installer did nothing to the system just a straight swap. He did have recommendations, which he says he can no longer carry out as he is not HEATAS anymore? Hence now they've asked me, so trying to piece the puzzle together.
    Replace hw cylinder and fit a relief (easy)
    Replace plastic f&e with metalic one and copper overflow (easy if actually necessary)
    Remove wheelhead from heat leak rad (easy)
    Also he was going to fit something near the pump - all i can see is possibly the lack of an 'injector tee'
    Best - I didn't see a pipe stat anywhere in the airing cupboard. The instructions do show one on cylinder return but give no guidance on its operation. What is the purpose of the stat - to only switch the pump on when the cylinder return reaches a set point?
     
  6. SmokeyJ

    SmokeyJ GSR

    Apologies for the essays lol

    20180711_190105.jpg
     
  7. SmokeyJ

    SmokeyJ GSR

    Not sure if the fitting at the bottom is classed as an injector tee? Doesn't look like the ones I see online. (Pump is on the return)

    20180711_184135.jpg
     
  8. SmokeyJ

    SmokeyJ GSR

    Sorry, also any ideas what this fitting is? Looks like a kind of bayonet...
    Thanks

    20180711_184121.jpg
     
  9. Ric2013

    Ric2013 Plumber

    Old-fashioned pressure release valve, I reckon. Looks like it has started to leak.
     
    • Agree Agree x 1
  10. SmokeyJ

    SmokeyJ GSR

    Was thinking that initially but it looks to work in reverse to a relief valve. I.e the spring must be internal to the valve, keeping the plate pushed closed like a bayonet. Whereas a relief valve usually has the spring external of the valve. Also the two lug holes and groove made me think it's a bayonet, but couldn't see the purpose for it.
     
    • Informative Informative x 1
  11. Best

    Best Trusted Plumber

    Yes, the pipe stat on return primary 28mm pipe (to be fitted at cylinder) is for to turn the pump on before the boiler boils and to turn it off when heat from boiler drops.
    The tee piece in the photo is indeed an injector tee, so to pull the primary circuit circulation around and correct direction
     
    • Like Like x 1
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