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You will thank yourself a million times over for choosing tankless water heating. Be aware that there will be a slight delay for the hot water to arrive at your fixtures and that the money saved in standby loss is offset by the higher cost of equipment, gas pipe, flue pipe and materials. [1]

  1. Tankless water heaters generally require larger diameter gas supply lines, higher voltage power supply (if contemplating electric on-demand), dedicated - special stainless steel flue (known as Category II, III or IV) or larger diameter exhaust system. Please take these things into consideration before you decide to DIY.
  2. This will allow for simple, easy de-liming maintenance process in the future.
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  3. [2]
  4. You will probably have some water left in the line even though your main has been shut off. Place a bucket underneath water bib to catch any spills.
  5. for gas, (propane) make sure the supply valve is closed (this is usually determined by the direction of the handle to the valve sitting either in the same direction as the line "open", opposite the direction of the line "closed"). For and electric water heater, simply unplug the appliance from the wall outlet.
  6. Once you have completely disconnected the old water heater you must remove it from it's current parking space and make sure to dispose of it according to the laws in the area you live in. [3]
  7. Determine the location best suited for this appliance and make sure you have allowed for the proper clearances around it to comply with all state and local building codes.
  8. Mount tankless heater on wall according to manufacturers instructions, making sure that you have appropriately supported its weight.
  9. Typically tankless water heaters requires larger flue or special stainless steel flue. [4]
  10. If your water heater uses electricity, plug it in to the wall.* If your water heater is gas, you will need to hook up a gas supply line from the stub at the wall to the new water heater. Open the valve so that the handle is in the same direction as the line. [5]
  11. All that work was well worth it!
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Expert Q&A

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  • Question
    How do you determine what size of tankless water heater you need?
    Rob Calame
    Training Manager at Barnett Plumbing & Water Heaters
    Rob Calame is a Training Manager at Barnett Plumbing & Water Heaters, based in Livermore, California, and the Lead Instructor of their Water Heater Training Program. Founded in 2005, Barnett Plumbing & Water Heaters specializes in servicing and installing all water heater types including tank, tankless, and heat pump water heaters throughout the Bay Area.
    Training Manager at Barnett Plumbing & Water Heaters
    Expert Answer
    Look at the gallons per minute, (GPM) of a tankless water heater to understand how much water it can provide. Then consider the number of bathrooms, the size of the house, and the length of the pipes. Finally, think about the amount of usage and the number of people living in the house. Add up the GPM of the amount of water you want ready at any time, and use that to purchase your water heater.
  • Question
    If I have hard water, do I need a water softener in order to use a tankless water heater?
    Community Answer
    If you have hard water, I would recommend a whole house water softener system regardless of the type of water heater you have. Hard water will cause a deposit build up inside the tank of your traditional tank water heater, which will cause problems. It will also cause deposit build up in the tankless system. Beyond that, it will cause additional wear on all of your fixtures.
  • Question
    Do I need to mount a gas tankless heater upright, or can it be laid on its back?
    Community Answer
    As with any gas appliance, heat rises so the unit needs to be mounted upright and leveled.
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      Tips

      • You can scrap your old heater for money. Find a recycling center and take it there.
      • If you purchased an electric hot water heater, make sure it plugs in to a standard outlet power source. If it is only wired for a different voltage than your mains voltage (mains voltage is usually 100 V to 240 V depending on your location) then you must have an electrician wire that outlet for you (unless you are an electrician yourself).
      • Make sure that you have sufficient amps to operate the tankless hot water heater, additionally, it may require 3 circuits in your circuit box.
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      Warnings

      • Make sure your water pressure is sufficient for a tankless system
      • Be sure to check your local plumbing and electrical codes prior to starting. Some areas require a licensed plumber and/or electrician before working on plumbing and electrical systems. If in doubt, call your local city building code enforcement or utility company.
      • Be sure to read the directions carefully. Some units require the installer be certified to install the unit in order for the warranty to be valid. Also, some natural gas units require a larger supply and exhaust (read larger piping or larger electrical circuit) than a regular tank-type water heater, which would require a plumber and/or electrician to install.
      • If you use gas as a heat source for this appliance you should test your gas connection by spraying an adequate amount of soapy water on the union and watching for bubbles which would indicate a poor connection and leakage. Turn off the gas immediately and open all windows and doors until complete ventilation has occurred. Once you have cleared the room of leaking gas you can double-check your connection and remedy the problem. After repairing connection, test again!
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      Reader Success Stories

      • David Pollard

        Mar 7, 2017

        "It told me I need a larger vent, and it should be stainless steel. I still am not sure about the clearances ..." more
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