Reduce lag time for tankless

Discussion in 'Tankless Water Heater Forum' started by philp, Aug 30, 2009.

  1. philp

    philp New Member

    Great info - thanks!

    I'd like to put it under the kitchen sink (minimal lag time here would be the most useful) but I'm worried that at some time we would need more than 2 or 4 or 6 gallons of hot water at one go. Is there a way of switching back to the tankless if we needed a lot of hot water? e.g. some sort of valve that could be turned manually?
  2. flamefix

    flamefix New Member

    Exeter, England
    I couldn't find the flow reduction rate in the datasheet. Some boilers like the Viessmann have a comfort setting which keeps the water within the boiler pipework at temperature which may be sufficient for the lag of the boiler firing up and providing hot water, for anyone else thinking about 'tankless'.

    Two country's separated by a common language color, colour, tankless instantaneous water heater, plus the Atlantic of course ;)
  3. Dana

    Dana In the trades

    It's worse than that- there are regional & local variations in the US too (some call them "on-demand water heaters") as well as confusingly similar terms in use here like "tankless coil" (a heat exchanger located inside a hydronic boiler for potable hot water.) "Tankless" seems to be the term in broadest use here, as a means of distiguishing them from the ubiquitous storage tank water heaters used here. In much of Europe tank heaters are at least as rare as the copper finned water-tube boiler "tankless" type heaters are here. (I can't recall having seen any tank-type water heaters in the Netherlands when I lived there. Most homes there had two water heaters, one for the bath/laundry, and a smaller one for the kitchen. ) I'm not sure what the relative distribution is in the UK.
  4. ChuckS

    ChuckS New Member

    Aurora, CO
    Bingo, our tankless has a .5 gal minimum. We have waterpik ecoflo shower heads with the trickle setting but can't use it or the sandwich will get you if the loop has turned off. Now it would work while the loop is on BUT her showers go long after the loop shuts off.
  5. flamefix

    flamefix New Member

    Exeter, England
    So are your hot water cylinders (tanks) not made from copper? They are here and europe or Stainless steel. In Germany now the move is away from Copper altogether towards stainless steel tanks and pipework or plastic pipework.

    Having the two heaters makes sense for short draw hot water demand at the sink, or electric under sink 15litre heaters currently subject to boiler location you can get long draws before hot water hits the tap, resulting in cold water hand washes.

    Generally you'll find apartments and such high density housing have tankless systems installed. Some like in Poland that I have seen are on a form of district heating. In Germany I couldn't tell you the proportion but anyone with a basement will have at least a 500litre storage tank if not 750 to 1000litre. This will be supplied with solar and gas/oil/wood/pellet fired boiler.

    In the UK it was traditionally a tank and separate boiler, the system was generally open vented(ie atmospheric pressure not sealed) but from the late 70's combi boilers were introduced (I believe by Vaillant group) House builders took to them with relish as it freed up space in the house and cut down on installation time. Therefore a majority of houses are fitted with combination boilers, but not all some are still fitted with a system boiler and cylinder(tank). There are even some combination cylinders with inbuilt condensing boilers pressurised hot water to supply higher flow rates for power style showers.

    With current building regs here The latest round of Part L here is a further drop of 25% in energy usage on new build but not legacy(grandfathered) build. Moving towards 2016 when all new build property has to be low energy carbon neutral. I think we are looking at space heating requirements of 4kW heat input.
  6. rob27

    rob27 New Member

    Hot water up 3 floors

    Link below is for a device I have been using for 4 years. It doesn't speed up hot water but it does reduce water waste by recirculating the cold water until it reaches hot then shuts itself off. By using remotes one just has to click the remote a minute or so before using hot water. It can be installed by user without a lot of technical complications.

  7. MikeQ

    MikeQ New Member

    Space issues

    In many cases a tankless heater can be located closer to the main points of use than a tank could. This is particularly true with electric tankless since there is no exhaust to consider. Moving a water heater closer to the most common points of use is the single best thing that can be done for convenience and efficiency. My 28kW electric water heater is not much larger than a VCR and it can certainly crank out large and endless amounts of hot water.
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