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"Instantaneous water heaters"

Jack Member Posts: 1,047
I cringe every time I see this term used on the wall. In my experience the only instantaneous water heater is the little Insinkerator unit that mounts on the bottom of the kitchen sink. Back in about '79 I installed an "instantaneous water heater" for a Mrs Magillicuddy, up in Angwin, CA. When I pitched it to her she liked the idea of IWH. It didn't have a lot of capacity and we all know that the old B-vented units could be problematic, but Mrs M was an sweet older lady who lived alone and she like the idea of an IWH. The unit was installed in the garage. I showed her that it was working, gave her an invoice, got a check and I rambled back up the Silverado Trail to the office. By the time I got back to the shop there was a message. "Jack, I do not have instantaneous hot water." Back in the truck and down Rt 29 (it was the Napa Valley so both routes were beautiful) to Mrs M's place. She said she didn't have IHW. I said, "Sure you do Mrs M. Let me show you." I had absolute confidence in my ability to put this to rest. I asked her to hold the hot water line at the bottom of the IWH. I then went across the garage to the slop sink and turned on the hot water. She quickly let go of the hot pipe and I walked across the garage smiling like the cat who just ate the canary. "See Mrs M, you do have IHW." She replied, "Yes, Jack, but I don't shower down here." At that point, the sweet Mrs M's true colors came out. I was absolutely guilty of casual language in my selling of the system. She knew it and she pushed it. I about had to re-pipe her house to get out of that job. She had me and she was reluctant to let me go. We are now almost 20 yrs into "tankless/on-demand" water heaters being a significant play in water heating in the States. Unless you are installing that Insinkerator or such, be careful with "Instantaneous". You may meet my Mrs Magillicuddy!


  • jumper
    jumper Member Posts: 2,289
    Yes after almost forty years we still remember the true color jerks.

    For years I nursed grudges about when I was over-ruled on account of codes even when everyone knew my idea was more sensible. But in my old age I have a change of heart. No one can fault me for going by the book. Eventually something fails and then you're blamed for breaking code.

    Getting back to IWH I don't see benefit of tankless.
  • Jack
    Jack Member Posts: 1,047
  • captainco
    captainco Member Posts: 796
    As long as tank heaters maintain temperatures that allow the growth and survival of bacteria, viruses and diseases they will be unhealthy.

    Spending $3 - $5 a month for hot water instead of $20 - $30 a month might have some benefit. Keeping water hot throughout the house at all times might be okay in the winter for heating but it does add load for cooling in the summer. Maybe the first person using the hot water might have a slight wait, but then everyone after won't have to wait an hour for more to be made.

    Tankless were a problem in the 80's. I sold Thermar, Vaillant and Aquastar. They were natural draft. Their flow controls were very sensitive to scale. But once the Clearwave Water Conditioner from Field Controls came out, My customers rarely had to service their tankless heaters.

    The key to any appliance is the installation. Too often we blame the equipment for the mistakes the installers make.