(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 15 of 18

Thread: Tankless with well water??

Hybrid View

  1. #1
    DIY Member M3's Avatar
    Join Date
    Apr 2007
    Location
    Minnesota
    Posts
    39

    Default Tankless with well water??

    Without reading every thread out there, I haven't seen anyone questionusing a tankless with a well supply.

    We remodeled two bathrooms with a 40 gal tub and a 60 gal tub and have a multi head body-shower. The problem is that we still have a 40 gal tank heater... I knew it couldn't keep up with hot water and would have to get a larger unit, but am wondering if a tankless would be a good fit.

    The well water sits around 50 degrees F and I'm wondering which would be best...
    A: installing a good tankless
    B: using the current 40 gal tank heater as a staging tank (not heating) and installing a good 75 gal tank heater as the main
    C: installing just a new 75 gal tank heater
    D: using the current 40 gal heater as a staging tank (not heating) and installing a tankless as the main.

    E: Other ideas??

    I do have the room for two tanks but it would be a bother, and we plan on staying in the house for several years. My wife likes "hot" baths and showers and I don't want to be replacing this after 5 years.

    Thanks in advance for your insights.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,405

    Default

    What is your water hardness? What fuel do you have available? Electric would require a very significant supply. So would gas. On a bigger tub, it's nice to have large flow volume so you don't wait forever to fill it. This means you must put a huge amount of energy into the water to get it hot enough as it flows by the heat exchanger (think hand through a candle - a blowtorch will get you hotter when passing by at the same rate). To get the flow for multiple showerheads and other things that may be using hot, you may need multiple units.

    The varying pressure could present a problem as the temperature might either rise as the pressure drops (decreased flow), or it would be constantly adusting the burner, if it deals with that that way. There are ways to keep the pressure fairly constant with a well.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    DIY Member M3's Avatar
    Join Date
    Apr 2007
    Location
    Minnesota
    Posts
    39

    Default

    Thanks for the thoughts JD... water hardness is not too bad (as tested by a water softener company last year). I have natural gas and most of the supply lines going to the bathrooms are 3/4".

  4. #4
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    Location
    indianapolis indiana - land of the free, home of the brave....
    Posts
    4,243
    Blog Entries
    1

    Talking 75 gallon gas

    water heaters seem to last forever on wells, wether their
    is a lot of iron and hardness or not...


    you cant claim that with a tankless
    the water softener is required with the tankless..

    do you have a water softener

    also, I am not sure how well a taknkless works when the well has a pressure drop in it as the pump kicks on??

  5. #5
    Illinois Licensed Plumber SewerRatz's Avatar
    Join Date
    Nov 2008
    Location
    Chicago, IL
    Posts
    1,705

    Default

    I have seen a few tankless installs on wells, as long as there is a water softener, there would not be much of an issue. You will have to descale it on a regular basis. Properly sizing the tankless system will be more an issue for you. To be able to handle your multi head shower while others may be using hot water as well I would install a pair of Noritz N-0751M-DVC units. The DVC is a concentric direct vent unit, it also links easily with each other via one plug and play cord. Only real issue is making sure you have enough gas supply to both units and the rest of the gas appliances in the home. Many installs go horribly wrong when people assume their gas meter is properly sized. So its best to talk to your gas company about your meter size even if you decide to go with a single tankless unit.

    So other than proper gas sizing and the cost to install two units it would give you endless hot water for years to come as long as you descale them on a yearly schedule.

  6. #6
    In the trades Dana's Avatar
    Join Date
    Jan 2009
    Location
    01609
    Posts
    2,720

    Default

    Do you have a hydronic (forced hot water) heating system?

    If yes, the better option is likely to be an indirect-fired tank running off the boiler. Done right, that will usually be both a cheaper & higher-efficiency way to get the hot water (improving the as-used AFUE of the boiler), with none of the flow & cold-water sandwich issues associated with a tankless. If the boiler's output is on the low side for an indirect, you can up-size the volume of the indirect to meet your tub-filling capacity needs.

    An indirect-fired tank will generally outlast the boiler, with lifetimes similar to or exceeding a tankless, and much lower maintenance to boot. And an indirect's standby losses are miniscule compared to a standalone tank. When the heating system is hydronic, indirect-fired hot water is almost ALWAYS the better/cheaper/more-efficient way to go. Summertime efficiency won't generally be as good as a tankless, but it can be close (depends on the mass and combustion efficiency of your boiler.)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •