Insta-hot vs third hot loop

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by thekid1, Feb 19, 2020.

  1. thekid1

    thekid1 New Member

    Joined:
    Dec 12, 2013
    Location:
    Long Island, NY
    Hello,

    I know there are a lot of variables that go into comparing the cost of each way to do this, but I was wondering if someone can give a ballpark answer.

    I am not asking about install costs, I am asking about which way is cheaper to run each system.

    If I had a sink that was far away from a hot water heater, would it be cheaper to run a third hot water loop with a circulator pump that's turned on by the light switch upon entry to the bathroom?

    Or

    Would it be cheaper to put an insta-hot on the hot water line right at sink?
    1) Does the insta-hot continually run and keep the water hot, or does it turn on when it senses water flow? If it continually runs, I would obviously have the light switch control a relay that turns on the insta-hot upon entry to bathroom.

    So given these two installations, which way would be cheaper. Like I said, I know there are a lot of variables here, but looking for a general answer.

    Thank you.
     
  2. James Henry

    James Henry In the Trades

    Joined:
    Jul 23, 2019
    Occupation:
    Plumber
    Location:
    Billings, Montana.
    I've replaced many point of use heaters. You need an electrical outlet under the sink and the 240 volt ones work better than the 120 volt ones. They go bad in a few years. It's a toss up which way you should go. I would probably go with a recirculation line.
     
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  4. thekid1

    thekid1 New Member

    Joined:
    Dec 12, 2013
    Location:
    Long Island, NY
    1) Why do they go bad so soon?
    2) How do they generally work?
    - Do they heat the water when it senses water flow, or is it constantly maintaining temperature?
    3) I used a sink as an example to keep the question simple, but really what I need it for is the bidet spray hose on the toilet. It is just too cold coming out when it hits your leather cheerio. But I assume the same install applies?
     
    Last edited: Jan 21, 2021
  5. thekid1

    thekid1 New Member

    Joined:
    Dec 12, 2013
    Location:
    Long Island, NY
    1) Why do they go bad so soon?
    2) How do they generally work?
    - Do they heat the water when it senses water flow, or is it constantly maintaining temperature?
    3) I used a sink as an example to keep the question simple, but really what I need it for is the bidet spray hose on the toilet. It is just too cold coming out when it hits your leather cheerio. But I assume the same install applies?
     
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
    Occupation:
    Semi-Retired
    Location:
    NW Ontario, Canada
    Umm... Insta-Hot provides boiling hot water for making hot drinks, not for washing.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    It might be an option to buy a bidet that actually heats the water rather than relying on the incoming water to be hot.

    For that application, a small point of use water heater would work and you could use that for the sink as well. Depending on how far away you could put that tank, and the low volume of water a bidet uses, you still might get a cool shot before the warm arrives, which is why having the seat do it where it's right there, has advantages even with recirculation.

    All of the residential hot water recirculation systems (not something cobbled up) don't really ever get the whole line hot. Most of them shut down when the sensor sees about 105-degree F water. The one I have does it at 95-degrees. Full hot isn't far away. If your pipes are properly insulated to pass current codes (they did not require this on older installs, but has always been a good idea), your actual cost isn't huge to just let it run, but a timer to only do this when it's likely to be needed can help, as often, late at night when things get the coldest, you could leave it off. The circulation motor on the one I have only draws about 9W, and only runs maybe 5-minutes an hour. My hot water pipes are insulated, so that helps. I have an indirect, and the boiler is a condensing, highly efficient unit, so heating the water doesn't cost much, either.
     
  8. John Gayewski

    John Gayewski In the Trades

    Joined:
    Aug 7, 2021
    Location:
    Iowa
    Factor in the that thr point of use heaters are junk in your cost analysis and it's a no brainers. You only need the tiniest of pumps.

    But the bidet needs to be cooler than your hot water. I'm gonna suggest you try full on hot water on your leather cheerio before you think about heating the water just like the text if your water. Truthfully you need a mixing valve.

    Get the heated bidet.
     
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