Results 1 to 6 of 6
  1. #1
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,546

    Default Parallel water heaters question.

    The Rinnai tankless gas water heater is hooked up in parallel with a conventional electric tank heater. You can see a tee above the tank in the third pic where the hot line from the tank can be shut off.
    There is a pump on the hot line from the tankless heater.

    I gawked at this for several mins, then moved on. So here was my client's question: "When we run the hot water, which heater is the water coming from?" "Both," I said???.

    Can anyone explain why this was installed this way?

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Last edited by John Kogel; 08-24-2009 at 01:57 PM. Reason: Pics attached I :>)
    NHIE Practice Exam

  2. #2
    Join Date
    Mar 2007
    Location
    Spring Hill (Nashville), TN
    Posts
    5,847

    Default Re: Parallel water heaters question.

    With a tankless system that also has a recirculation pump you need to have a conventional water heater tank in the line. If you do not have it this way then you will not have the instant hot water at the fixtures.

    I had a little trouble seeing what you are talking about in the picture.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  3. #3
    Join Date
    Mar 2007
    Location
    Connecticut
    Posts
    1,828

    Default Re: Parallel water heaters question.

    kind of defeats the purpose of a tankless water heater. Unless it cannot keep up with demand, which I would assume in this case.


  4. #4
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,546

    Default Re: Parallel water heaters question.

    Quote Originally Posted by Scott Patterson View Post
    With a tankless system that also has a recirculation pump you need to have a conventional water heater tank in the line. If you do not have it this way then you will not have the instant hot water at the fixtures.

    I had a little trouble seeing what you are talking about in the picture.
    Thanks, Scott. I've seen the tankless used alone, but don't recall if they used the recirc pumps in those cases.

    Quote Originally Posted by Wayne Soper
    kind of defeats the purpose of a tankless water heater. Unless it cannot keep up with demand, which I would assume in this case.
    Two big soaker tubs and a mega shower, maybe that's a good ass-umption.
    I think there are enough valves so one heater can be turned off when demand is low.
    Looking at the pics now, I see one valve on the tankless was turned off.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images

  5. #5
    Join Date
    Mar 2007
    Location
    Spring Hill (Nashville), TN
    Posts
    5,847

    Default Re: Parallel water heaters question.

    Quote Originally Posted by wayne soper View Post
    kind of defeats the purpose of a tankless water heater. Unless it cannot keep up with demand, which I would assume in this case.
    It's not that they can't keep up with the demand but more along the lines of having instant hot water on demand at each fixture in the home.

    The tankless units heat only when the water flows through them. With a recirculating pump it does not produce enough flow on it's own to activate the heating unit in the tankless units. This is why you need to have a small 2-5 gallon electric water heater in the loop with the recirculating pump, it is only heating the water that is in the pipe. The WH tank in the picture is over kill.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  6. #6
    Join Date
    Mar 2007
    Location
    Charlotte NC Licensed in NC and SC
    Posts
    597

    Default Re: Parallel water heaters question.

    Some pumps have enough flow to activate tankless heaters.

    Here is a circulator pump made for tankless water heaters:

    Tankless Water Heater Pump-Tankless Water Heater Pump

    The cheap circulator pump at lowes worked on a 240V 80amp tankless I helped a guy install. Maybe the gas ones are more sensitive and would need the one at the link above.

    Bruce King, B.A. King Home Inspections, LLC
    www.BAKingHomeInspections.com
    Certified Master Inspector, Independent Inspectorwww.IndependentInspectors.org

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
  •