Instant hot water tap for bathroom

Discussion in 'Plumbing and Central Heating' started by silver50, 6 Dec 2021.

  1. silver50

    silver50

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    My mother is disappointed with how long thier Combi is taking to supply hot water to bathroom sink. They’re planning a new vanity unit/cupboard soon so asked me my thoughts.

    I see some instant HW kitchen (3 in 1) taps that’d probably look ok at a bathroom sink.

    I don’t entirely understand why some are so expensive.

    My father is suggesting housing a https://www.screwfix.com/p/ariston-...y-RAEsEXcVW-DGKib2hoCd-YQAvD_BwE&gclsrc=aw.ds

    I just wondered if anyone had any good suggestions (other than the obvious, be more patient!)
    Thanks
     
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    cross thread

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    That sort of thing is a great idea
     
  4. oldbuffer

    oldbuffer

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    1. That heater obviously requires an electrical supply. I suspect any socket or connection point would have to be outside the bathroom.
    2. You'd have to make sure there were no valves of any sort in the supply of cold water as the expansion is accommodated in the cold pipework.
     
  5. BlueLoo

    BlueLoo

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    Make sure the Combi and the piping are working and properly set up 1st.

    Or that they are using it properly.
     
  6. oldbutnotdead

    oldbutnotdead

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    They're likely stuck with a certain amount of lag due to pipe distance from boiler (in kitchen) to bathroom sink. Check that the hot feed is connected so there isn't a massive long run from kitchen to old airing cupboard then back to bathroom.
    Depending on the combi model, they could try the preheat function (where the dhw hex is kept warm all the time).
    That heater you linked to isn't an instant heater, it's a small storage tank type, so will use a certain amount of energy to keep the tank warm.
    You can get instant undersink heaters, 10kw will give you a good hot water flow long as you don't mind paying between 2 and 4 times as much to heat the water. And as long as you don't have an electric shower already.
     
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  7. Mottie

    Mottie

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    I installed one of those types of water heaters in an old workshop once and the one I fitted came with its own taps - you had to use them as they incorporated the expansion in them.
     
  8. silver50

    silver50

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    Thanks for replies

    at present there are waterfall type taps in the bathroom. I wonder if they have a poor flow rate, hence slowing up delivery of hot water?

    What’s the regs on likes of the Ariston as far as expansion/blow off? Can a discharge pipe go into the basin waste?
     
  9. cdbe

    cdbe

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    If you can get a length of 10mm plastic pipe directly from boiler to tap it could make a big difference, if the boiler is in the kitchen you would get a similar delivery time as to the kitchen hot tap. If the combi is a replacement for an old traditional system the water is probably running halfway round the house in 22mm.
     
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  11. silver50

    silver50

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    Only a 12 yr old house but 7 years ago the combi seemingly replaced a Glen.. something (Glenham/Glenfield? Seemingly still make water cylinders but not so much boilers..) all in one boiler with tank incorporated into it.

    The boiler isn’t actually very far away from the bathroom but there are two bathrooms and of course kitchen and I don’t know where all pipe work runs.
    Is the water supply side from a boiler usually in 15mm? I think all visible pipe work below the boiler was indeed all 22mm.
     
  12. BlueLoo

    BlueLoo

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    Here's a thought based on my limited experience with combis.....

    To get the boiler to fire up, you turn the tap on full. but, on full, the water isn't going to get hot. You turn the water down knowing it isn't going to get hot enough which shuts off the boiler and so on and so forth (the combi i used was rubbish admittedly).
    Waterfall taps can be high flow as they are lever type, so the tendancy is to have the tap on full, regardless of the requirement and thus the hot water is never going to get hot enough.

    Perhaps if the water pressure in the house is good, adding a restrictor to the HW tap may help the user keep the flow low enough to get the water hot enough?

    I could be way off the mark here so take the above with a pinch of salt......
     
  13. silver50

    silver50

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    Cheers for thoughts on it. I’m going to experiment with it a bit myself. My folks said the (mixer) shower in the room heats quickly but tbh its over the other side of the biggish bathroom and could be on a faster route from the boiler.
    A combi shouldn’t be too sensitive to water flow, as in it shouldn’t turn off unless you’ve turned the flow to very slow/almost off at a tap.
     
  14. ianmcd

    ianmcd

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  15. ianmcd

    ianmcd

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    check the taps in the bathroom sink, if they have 10mm flexi hoses as the final connection, that is likely to be your problem
     
  16. silver50

    silver50

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    Thanks for posting the video. I imagine a lot of mixer taps do use M10 flexi’s.. possibly not easy to find ones that don’t?
     
  17. ianmcd

    ianmcd

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    you are correct but they seriously restrict the flow hence the longer time taken to get hot
     
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