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Fabdec Excelsior Hot Water Cylinder?

Discussion in 'Plumbing and Central Heating' started by Philayl, 27 Feb 2020.

  1. Philayl

    Philayl

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    Hi All, I happened to mention that I was considering replacing my ageing boiler and vented HW cylinder with a Veissmann Vitodens 200-W System boiler and the HW cylinder with the above unvented indirect one, my main reasoning is that has a self sustaining air gap and doesn't need an expansion tank. A number of people have advised against using this HW cylinder but no one has given me a reason why not. Can anyone on here enlighten me as to why this is an ill considered move? Many Thanks, Phil
     
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  3. ReJect

    ReJect

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    The air gap (in the internal gap type cylinder) isn’t self sustaining.
    You have to partially drain the cylinder and open top pressure/temperature relief valve to allow air in and then refill.
    Other than that I would just want to know the reliability of the unit.
    Warranty is good, just same as most other brands.
    If you opted for the external expansion vessel type, the vessel is checked and recharged as necessary on yearly service by a G3 unvented qualified plumber, which you must do to keep 25 year warranty and for safety and proper functioning.
    So external vessel type is no different to internal air gap type for service requirements.
     
  4. bernardgreen

    bernardgreen

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    Or have a vented hot water cylinder and avoid the cost and hassle of the annual safety check. ( Boiler still has to be serviced )
     
  5. Philayl

    Philayl

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    Will I still need a cold water supply tank in the loft with a vented HW cylinder, I was hoping to do away this this. Phil
     
  6. bernardgreen

    bernardgreen

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    Yes.
     
  7. Elkato531

    Elkato531

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    And you'll need a noisy unreliable pump if you want a decent shower. Unvented is the way to go.
     
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  9. bernardgreen

    bernardgreen

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    Use a second coil in the top of the vented host water cylinder to heat mains water on route to the shower. No pump and no need for any G3 servicing and safety checks. Also the supplies to basins are not at mains pressure so water does not bounce out of the basin when the tap is opened too far,

    twin_coil.jpg
     
  10. ReJect

    ReJect

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    Unfortunately, although a simple solution, the coil solely for a shower just won’t gain enough heat as you shower. I had actually considered fitting a cylinder with a high gain coil in my own house, but flow rates would have had to been very low for adequate heat to shower. Think (not certain) the coil was a soft coil multi coil microbore for high gain, which is also a risk of rupturing in high mains pressure.
    Mains water to basin taps is better as drinkable and you can restrict the flow by fitting an aerator on tap spout, but if that ruins the gravity hot flow you could just fit a flow restrictor into the cold pipe to tap.
     
  11. bernardgreen

    bernardgreen

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    It does in my cottage, agreed that after a long shower the time to re-heat can be a trivial inconvenience ( it is a 16kW heat only boiler ).

    The shower coil is rated for mains pressure.
     
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  12. ReJect

    ReJect

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    Useful to know. That has got be reconsidering the option of using a cylinder with shower coil.
    I would be happy with solely a mains fed shower and rest of outlets gravity fed
     
  13. bernardgreen

    bernardgreen

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    When calculating the volume of the hot water cylinder take account that the volume of water is reduced by the volume of copper in the second coil. It means there is less stored heat than in a normal hot water cylinder

    Check with the supplier that the shower coil is rated for mains pressure. When I ordered my cylinder I did say that the second coil was for mains pressure.
     
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  14. Philayl

    Philayl

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    I have had a pumped shower for 8 years and can't call it noisy by any means, it gives a hum that is barely audible and gives a fairly powerful shower, I would happily stay with a pumped shower but it is the header tank in the loft for the HW cylinder that is in a bad way and I would like to remove it from the system, this is why I am leaning towards an unvented self sustaining system. Phil
     
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