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On demand hot water heater and a holding tank question, also NAVIEN any good?

JoeG
JoeG Member Posts: 88
Hi, I am looking at getting the NAVIEN Model # 240 with the circulator pump on Demand Hot water heater. I need one that can produce alot of hot water I have a big whirlpool tub to fill and I like long showers. There are at times Six peopl in the house.

1. I have a fairly new 50 Gal bradford white propane hot water heater that I d like to use as a storage tank any tips on plumbing it?

2. Is this a good way to go? The bradford white couldnt keep up with demand.

3. Aer the Navien units anygood?

Comments

  • Jack
    Jack Member Posts: 1,048
    Tankless

    are all about flow and temp rise. how many gallons in the tub and how fast does it fill? Get a bucket and stop watch, time it. Or figure out the cu ft of the tub to the level you typically fill it. 7.48 gallons/cu ft. As I represent Rinnai I will limit my comments to Rinnai. For a large household the RC98HPi model will at 70F rise provide 5.4 gpm. The V75LSi model will make 4.3 at same. A good showerhead is 2.5 gallons at 112F. Low flow showerheads are 1.5. Clock you faucets. Energy conservation is all about water conservation too.
  • JoeG
    JoeG Member Posts: 88
    Whats Temp Rise?

    The tub I think is 100 Gal. I also have a shower tub combo standard and another shower. Plus 4 sinks washer and dishwasher.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,372
    If water quality is good

    you should stream line and just use the tankless unit and keep the system streamlined.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • JoeG
    JoeG Member Posts: 88
    Not sure how the water is

    The company recommended a holding tank they were worried about teh tub, I am unsure why the tub would effect it. as long as teh gpm was the same.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,372
    edited August 2010
    They may be worried

    about how long it will take to fill if the water heater is sized to suit all your other needs. Note on rise, my well water is 43 degrees Fahrenheit all year long. the 70 degree rise would only give me 113 degrees F not quite what I need to do dishes or shower. As the rise needs to increase the units become quite large. In order to make a sale some contractors are selling underrated units and collecting their money and leaving jobs that simply do not work as was understood. What is your heat source for the rest of your home?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • JoeG
    JoeG Member Posts: 88
    Force hot air

    As of now it is forced hot air. Down the road Ill prob change it.
  • Jack
    Jack Member Posts: 1,048
    43F year round!!!

    Charlie, please check that. What I have typically;) seen with water supplies in New England is in line with the USGS surveys. 52-55F summers. Usually what I see is a period of about 3-4 months, Jan-March, where the water temps may be depressed into the 40's. Every system has a personality of course, but it takes time for the frost to get to the water supply piping. Once there it takes time for it to come out.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,372
    Granite and marble deep well

    I have checked the temp on many occasions it is 43 year round. Maybe as high as 45 in the dog days of summer.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Temp Rise

    Temperature rise is the difference between the cold water coming into the unit and the hot water leaving the unit. DO NOT EVER, EVER size an on demand heater off the charts the manufactures provide. Seen too many issues using them. The proper way to size an on demand heater is as follows:



    gpm x temp rise x 500 = btu's required

    Example:

    If I want to make 7.5gpm in my market to 120 degree water temp.

    7.5 x 70 x 500 = 262,500 btu's. I need an on demand heater that can produce 262,500 btu's. If I lived in a wamer climate that rise would change thus my btu requirement would change. The literature manufacturers produce is nation wide not for particular parts of the country.

    There was an error rendering this rich post.

  • JoeG
    JoeG Member Posts: 88
    Temp Rise

    So how do I find out the temp of the water in NY ? Any help on the btus I am looking for? I plane on Ordering a navien 240 A which is there biggest unit.
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