H2Flow

Discussion in 'Tankless Water Heater Forum' started by AmyTankless, Jun 10, 2013.

  1. AmyTankless

    AmyTankless New Member

    Messages:
    2
    Location:
    Arizona
    Hello. I have 2 Noritz tankless natural gas water heaters, each with its own H2Flow filter. I know the manual says to change the H2Flow filter every 2 years, but I don't want to change the filters earlier than is really necessary. Is there some way to tell when the filter needs to be changed or are we stuck using the calendar as a guide?

    According to Tucson Water company, the hardness is 247 mg/L in my water zone (and Sodium is 65 mg/L, Minerals 505 mg/L, pH 8.0). My household is 2 adults who love long showers, but we don't use hot water for clothes washing, and the dishwasher is only run 2x week.

    Any advice appreciated!

    This is my second home with tankless. The first home was with an electric unit (no gas in the neighborhood). The tankless replaced a tank for (a) unlimited hot water and (b) reclaim space. We had to de-scale it every 4 months or we'd stop getting hot water. Now this second home is zoned into two halves so that hot water lines/runs are relatively short - one zone has the master bath which is heavily used and a second bath (rarely used), and the other zone has the kitchen and a 3rd bath (rarely used). Our hope is that with the H2Flow filtering we won't have to do the de-scaling operations at all. Not that the descaling is a difficult chore, we just know for many reasons we're better off with as low a maintenance schedule as possible.

    Thanks,
    Amy
  2. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    Descaling schedules are about the total volume of water heated per month/year, the temperature of the water, and the mineral content. Hard to say a-priori what schedule will make sense, even if "long showers" were a well defined concept.

    At some showering duty cycle things like drainwater heat exchangers make economic sense on fuel-savings alone, but they also cut the flow of water through the tankless roughly in half, for most 4"x 48" or 3" x 60" versions. Since most of your hot water use is clearly for showers, a drainwater heat exchanger would dramatically extend the descaling schedule, doubling the time between descaling if you have room for installing a bigger one.

    They do nothing for batch draws like tub fills- they only work when drains & hot water are running simultaneously. They also need to be installed vertically to work, which is hard to do for first floor showers in slab-on-grade construction, but fine with full-basements or second-story showers. They come as short as 24", but the return efficiency of stubby & skinny unit isn't very high- taller and fatter = higher efficiency.

    [​IMG]

    Insert a tankless for the tank in that diagram- it's done all the time:

    [​IMG]
    Last edited: Jun 11, 2013
  3. AmyTankless

    AmyTankless New Member

    Messages:
    2
    Location:
    Arizona
    I've never heard of a "drainwater heat exchanger" - interesting idea, but not doable in my already-renovated-single-story slab foundation home! Too bad I didn't learn of these two years ago in the planning stage. I'll store the idea for later, although I swore I'd never renovate again. Thank you for the information :)

    For my swimming pool, I periodically remove the cleaning filters and hose them off with moderate pressure from the garden hose - any point in doing something similar with the H2Flow filters?

    Thanks!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,814
    Location:
    New England
    Typically, a filter can only remove solids, but there are some that can remove chemical impurities (like activated charcoal). From what I've seen, there is no verified, reliable filter that will remove hardness from water...it takes a chemical reaction as in ion exchange to convert those minerals into water insoluable materials that then actually remove them. Particulates sometimes can be safely removed from a filter and those designed for backwashing are expected to perform well in that manner, but your efficiency with filters not designed for it may be lacking.
  5. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    Yabbut, Jim, the H2Flow is a Noritz product specifically targeted at reducing scaling.

    They don't say on the short-sheet exactly what's in the cartridges, but state in alternate places:

    " Change the H2FC cartridge at least once every two years."

    ...and...


    "If the system sizing recommendations have been followed,
    the H2Flow™ cartridge should last two years."

    ...and...

    "Our obligation under this warranty with respect to the H2Flow™ media will be limited to furnishing a replacement for the media within two
    years from date of original installation."

    There's something magic about two years, but it's not clear what that magic derives from. Compare notes on the "conditions" list, and mark your calendar.

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