One isolating valve on both loft tanks inputs?

Discussion in 'Plumbers' Talk' started by phloaw, May 23, 2020.

  1. phloaw

    phloaw Member

    Hi, just after the mains stopcock under my kitchen sink I have a tee, one pipe to drinkable water+washing machine and the other to the loft cisterns (talking about an open vented pumped S-plan system, standard here in UK).

    I was wondering whether it is safe to add an isolating valve on the latter pipe, placing it right after the aforementioned tee (i.e., under the kitchen sink).

    I am asking because I've read somewhere that the feed and expansion tank shouldn't have a valve on its input, but I couldn't find a consensus on that, online.

    I am also suspicious because currently I have an isolating valve just before the bigger loft tank in the loft, not serving the FE tank. Which could be a hint that FE shouldn't have an input valve?
  2. terrymac

    terrymac Screwfix Select

    It shouldn't have an isolation valve on the outlet from the f&e tank ,but on the supply to it is perfectly ok. It needs to be close to the tank though ,not far away in the kitchen.
    phloaw likes this.
  3. phloaw

    phloaw Member

    Good, thanks.
    Why is that?
  4. terrymac

    terrymac Screwfix Select

    Near to tank for ease of maintenance.
    The outlet ( which is feeding the central heating / boiler system) accommodates the expansion, when water is heated by the boiler it expands. Hence the term feed and expansion tank !!
    So no isolation valve on outlet ,not needed (and if closed prevents the accomodation of expansion)
    phloaw likes this.

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