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Thread: Fine tuning tankless water heater on well system

  1. #16
    DIY Junior Member artbob's Avatar
    Join Date
    Nov 2009


    You all have given me some info to chew on. I have found if I turn the temp down to 105 and have hot water only it gives good pressure in the shower with only slight temp variation. We will be remodeling the bathrooms and I'll get low flow fixtures. I didn't realize that tankless is such a different animal but I think we can live with it.

  2. #17
    Homeowner Thatguy's Avatar
    Join Date
    Aug 2008


    A tankless heater should have a spec on GPM vs. temp rise since it heats the water on the fly. A tank heater doesn't need it.
    1 GPM = 8.3 # of water per minute and requires 8.3 BTU for each 1F rise above incoming water. A 70F rise would need 580 BTU/min = 35,000 BTU/hr.

  3. #18
    DIY Junior Member jnyost's Avatar
    Join Date
    Dec 2009
    Mid Ohio


    What's your well pressure switch set at?

    Ours works very well with our well.

    We added onto our house and didn't have the money to do anything with our how water system yet. I've been very surprised to see our TK-2 keep up. I'm still planning on some changes soon but it seems to be working for the moment.

  4. #19
    Macintosh Computer Consultant/Tech macmikey's Avatar
    Join Date
    Dec 2009
    Phoenixville, PA


    Quote Originally Posted by ChuckS View Post
    I'm no expert but the guy who installed mine put it right by the gas regulator and said the length of the gas line makes all the performance difference. For all I know he could have been FOS.

    I do know from testing mine increasing my water pipes to 3/4 made a big difference. I also noticed you can use more showers if you lower the temp to say 105'.

    I do agree with you that yours appears to be limiting somewhere. I would say lower the temp to 105 and if you see more pressure then you know the problem is in the tankless. I'd call the manufacturer to see what they say.
    I agree here as well. From my (not) vast experience with Plumbing and repairs, I had my main run pipes all sized up to 3/4" and 1/2" runs off those to each device. It seems to have made the 2 showers and the LG front loader to get all they need and a minimal pressure drop (well supplied, large bladder tank).

    The LG front loader is a different story though. Its filling procedure is driving the tankless crazy..... on/off, on/off, many times in the short fill period of the washer. But, thats for another post



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