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General: DHW Long Pipe Runs - Is there an alternative?

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  1.  
    • CommentAuthorPingy
    • CommentTimeDec 3rd 2007
     
    Has anyone got any suggestions how to provide hot water to an ensuite. The ensuite will be more than 20m from the main heat source (log boiler with heat store). As I see it I have several options:

    1. Accept a long pipe run and waste a lot of water.
    2. Install a small electric water heater for the basin and fit an electric shower.
    3. Wash/shower in cold water.
    4. Do away with the ensuite and join the queue for the bathroom.

    None of the above are particularly attractive so I thought you'd be able to help with an alternative or convince me one of the above is better than the others.
    • CommentAuthortony
    • CommentTimeDec 3rd 2007
     
    3. is the greenest! !. is the practical answer-- try to use the "wasted" water for something useful.
    • CommentAuthorTuna
    • CommentTimeDec 3rd 2007
     
    How are you getting heat to the bedroom that the ensuite services?

    You can get funky highly insulated pipework that's used to connect solar panels to tanks where the panel has to be some distance from the tank, but you then have the secondary problem that it takes ages for the hot water to reach the tap when you turn it on. One solution to this is then to have a hot water loop that is continually pumped at a low flow rate so that hot water is then readily available throughout the loop. I've no idea what the heat loss would be though as it sounds pretty inefficient.
    • CommentAuthorPingy
    • CommentTimeDec 3rd 2007
     
    Tuna,

    the heat to the bedroom will be underfloor heating pipes. That's not a problem but I'm concerned about the amount of wasted water coming out of the tap before any hot water appears. I suppose I could run the hot water next to the underfloor heating pipe so that it's pre-warmed that way.
    •  
      CommentAuthornigel
    • CommentTimeDec 3rd 2007
     
    some tanks allow you to have a pump secondary dhw circuit (with a timeswitch) so that the hot water can be kept hot in the insulated dhw pipe.
    • CommentAuthorBluemoon
    • CommentTimeDec 3rd 2007
     
    My Grandfather thought nothing of washing in cold water, and I don't think much of it either. I have the same problem, a long run from the cylinder. I am fitting a pump, though I can't use the cold water for anything else
    • CommentAuthorskywalker
    • CommentTimeDec 3rd 2007
     
    DPS (google heatweb) certainly have an option on their stores to keep long runs hot to prevent this problem. Not sure about the running costs though.

    I mention them by name as they have been very helpful (read patient & stopped me wasting money here) to me and to a number of others I know of. Others probably do the same sort of thing.

    S.
  8.  
    I would think that item 2 a small local electric heater (but perhaps loose the shower) would be greenest as it would only heat exactly what you wanted, as you wanted it and would not fill long pipe runs with hot water. It would probably go under the sink and could feed the sink in small bore 10mm pipe so very small volumes of water. That might offset the increased cost of elec vs gas/oil. I haven’t worked it out – just a bit of guesswork. The circulation systems might be on a timer so the pump is not always on - saves electric, but still uses it. The pump must be bronze as this is potable water not a heating pump so it’s going to be £150+. If the timer has the pump off at night, then when it restarts the cold water in the pipes will return to the hot end of the tank as it would expect to circulate hot water. I’m not a fan of constantly circulating hot water. Cheers Mike Up North.
    •  
      CommentAuthorfostertom
    • CommentTimeDec 4th 2007
     
    Posted By: nigelsome tanks allow you to have a pump secondary dhw circuit (with a timeswitch) so that the hot water can be kept hot in the insulated dhw pipe.
    If the ensuite is some vertical distance above the HW cyl, the secondary circulation can be by unpumped thermosyphon. If pumped, no need for time clocks. Put a push switch outside the bathroom door; one push works a relay that switches the pump on, which then runs until a sensor just downstream of the bathroom, on the return pipe, detects 45oC and then switches back the relay and hence shuts off the pump. Thus the pump only ever runs for a minute or so, just until it's brought hot water to the bathroom, then stops. Minimises standing losses in the out and back pipework; minimises electricity to drive the pump. All secondary circulations need a non-return valve in the return pipe, otherwise when you open a tap it draws water through the return as well as the outward pipe.
    • CommentAuthorPingy
    • CommentTimeDec 4th 2007
     
    I like your suggestion fostertom as it minimises the pump running time. One problem I can see is that I'm planning on installing a mains pressure hot water system. Any suggestions as to how it could be done?
    •  
      CommentAuthorfostertom
    • CommentTimeDec 4th 2007
     
    Makes no difference - the secondary circulation is at mains pressure. The 'out' pipe comes off the normal top outlet of the cyl (it is in fact the normal supply pipe), the 'back' pipe ideally goes back into the cyl by a separate tapping half way down - but that's for when the normal bottom inlet is tank-fed - I suppose if it's mains-fed the return could go into the same tapping as the mains-feed. Anyone know? You'll need a bronze or plastic pump, not an ordinary central heating pump, otherwise the oxygen in the fresh water will corrode it. Note that the pump doesn't have any effect on the tapwater pressure - it's not set up to be a pressure booster.

    As well as the 'on' push switch, you need an indicator to show when the pump's running, and an 'off' push switch so you can switch the relay and pump off in case there's no hot water coming through to activate the 'off' temp sensor.
    • CommentAuthorPingy
    • CommentTimeDec 4th 2007
     
    That's great news. You've solved my problem. Thanks fostertom!
    • CommentAuthorhowdytom
    • CommentTimeDec 4th 2007
     
    if you have a reasonable water pressure you could use micro bore tube to minimise the volume
    • CommentAuthorPDobson
    • CommentTimeDec 5th 2007
     
    We are trying to decide between a recirculating system and a heated pipe system - Has anyone used the a heat trace type of system e.g. the one from heat trace northern (link below)? What would the energy requirement be compared to the pump system?

    http://www.htnuk.co.uk/page.asp?page=26
    •  
      CommentAuthorfostertom
    • CommentTimeDec 5th 2007
     
    Compared to the pump system I proposed, no comparison. Compared to normal e.g. timeclocked pump system, trace might be better.

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