which gas water heater?

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    • #278241
      MasterPlumbers
      Keymaster

      I’m trying to figure out which tankless natural gas water heater to go with. I measured my water usage and have a small house.
      Here is my usage:

      1.3g/min Bathroom sink
      1.5g/min Kitchen Sink
      2.3g/min for Shower

      We also have:
      Dishwasher (this can heat its water electrically and we never need to run it during showering) Washing machine (almost never use hot water, only during washing of whites and never during shower)

      As also we have a closed system spa (its own heater), thus, we do not shower very often or for very long. It also has an outdoor shower we use so the water is heated for that via the spa heater, no hot water heater is required.

      We only have two living in our house, though we plan on children. We also wish to add an addition in 2004. I’m willing to add another heater at that time.

      Our hot water heater sprung a leak and when I went to get a new one, I realized I should use this opportunity to try the new technology. I have read an article about it in “Handy” magazine and am convinced it will work for us.

      5gal/min (300g/hr) seems like it should work for us. I’d like to get your opinion about the brands you sell.

      4gal/min (200g/min) seems to be too close for comfort, but not sure.

      I’d like to use the vent for the current water heater I have. It appears to be as large as five or five and a half inches diameter vent.
      I’d rather not use a power vent.

      Can you please also tell me something about the required temperature rise for the usage described.

      Look forward to your suggestions.

      Thanks.

      Michael Vestel

    • #298078
      Selgas
      Participant

      Happy to assist.

      I take it from the terms you use that you are in the USA? that being the case I would strongly advise you to look at a Rinnai Brand of tankless water heater (down here we call them instantaneous units) as they are well proven Japanese manufactured units.

      The most popular size down here is a 24 litre/minute (6 US gallons/minute) at showering temperature.

      These units are connected directly to the towns mains supply so the outlet water pressure and volume is dang good. They can also have up to three temperature control keypads that allow the operator to select what temp they want the water to be supplied at – great for showering.

      Hope this helps.

      Cheers



      Selgas Services Ltd
      Craftsman Gasfitters, Plumbers, Electrical Service Technicians

    • #298079
      Selgas
      Participant

      Dam I only read half of what you wrote when I replied earlier so here goes the rest……
      1. Normally you could NOT use the same vent for the new unit as it is what is known as a balanced power flued device and requires a complete and separate fresh air intake to the combustion fan and burner inside the water heater. We almost always use the outdoor models which in fact are considerably cheaper top install and have the identical performance features of the internal unit with a special but very expensive balanced flue system.
      2. The temperature rise of all tankless water heaters is based upon the unit’s ability to heat a specific amount (litres/minute) at a temperature rise of 25 degrees C. For instance if the water inlet is say 10 degrees C then the maximum temp at FULL flow rate would be 35 degrees C. As the temp required increases the water heater’s computer controller slows the water flow down a little to allow the water to stay within the heat exchanger for a longer period which in turns increases the water temp at the outlet.

      Hope this data helps you to decide.



      Selgas Services Ltd
      Craftsman Gasfitters, Plumbers, Electrical Service Technicians

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