How to size a softener for low water usage with high flow fixtures

Discussion in 'Water Softener Forum, problems, installation and r' started by devsd, Jan 8, 2014.

  1. devsd

    devsd New Member

    Messages:
    10
    Location:
    California
    We moved into a new construction house a year ago with hard water. After checking the water bill, I was surprised to learn we don't use a lot of water. So now I am stumped because when I try to calculate what size softener to get to match our low water usage, it seems our high flow fixtures will over run it.

    Here's our stats:
    3 people averaging 160 gallons a day according to water bill over one year period. We have no yards to water, just a small garden.

    House:
    1 1/4" copper line in garage where softener will tie in. All copper pipes in new condition.
    2 - shower/tub combos.
    2 - stand alone showers. One of the showers has multiple heads. Haven't tested gpm but it flows a lot of water and want to keep it that way.
    1 - stand alone indoor jacuzzi tub tested at 15gpm flow.
    6 - toilets.
    9 - faucets.
    1 - dishwasher.
    1 - laundry washer (large).
    5 - outside hose bibs. Tested one bib at 10 gpm.

    Hardness - 71 to 350, avg 210 according to city. 250 according to my strip test. City water, no iron.

    160 gallons per day x 20 gpg (350 highest city#) = 3200 grains per day x 8 days = 25600 total grains per week.

    When I look at the smaller softener units like a Fleck 7000SXT 24000, the SFR rate is only 7gpm. I am guessing the peak flow would be more than that but I would get hard water with it. We don't use the high flow fixtures everyday but I want to make sure whatever I buy will allow peak flows of 15gpm or more if possible.

    I am looking at the Fleck 7000SXT with the 1 1/4" valve connections. My questions are:

    1 - Should I go up in size to accommodate our peak gpm needs or buy a smaller unit and just live with the occasional override of the limited SFR?

    2 - If a larger unit would be a better choice, what size would you recommend?
  2. Reach4

    Reach4 Active Member

    Messages:
    2,134
    Location:
    IL
    Select based on SFR. Derate the capacity, and adjust salt down to your grains. You will use less salt that way.

    There are threads on this you should read.
  3. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,828
    Location:
    Ontario California
    The peak softener flow rate is what you should look at for your application. Exceeding the softeners SFR on a rare occassion does virtually no damage to the system. A slight bleed of hardness, probably imperceptible may occur. Some people really try to push the SFR as the most critical item..., and regeneration frequency.

    Neither of these is as critical as some may portray except in extreme cases, like an earlier topic with the micro softeners under the sink. These systems are always being pounded way beyond their SFR, and the resin will fail in only a couple of years, but a 1 cu. ft. system would work, it is not recommended. Go bigger.

    My minimimum size recommendation for your application is a 2 cu. ft. system (12x52) with the 7000SXT For a multitude of reasons, but in general your plumbing is 1-1/4" for a reason. Size the system to the house, not the exact mimimum potential usage. A 2.5 Cu. ft (13x54) would be the largest I normally recommend except for special residential applications and would be my preference.

    A 2 cu. ft system would be set for high salt efficiency and would regenerate every 2 weeks or so using very little salt and water.

    Anything larger then 2.5 cu. ft. runs into problems of being to large, but then again, we have sold large numbers of 3-10 cu. ft. systems for residential applications, usually with no problems.
  4. devsd

    devsd New Member

    Messages:
    10
    Location:
    California
    Thanks for the info guys. I have been looking at various online shops for a 7000SXT 2.0cuft 64000 and 2.5cuft 80000grain systems. The 2.5cuft systems flow rate would be better for me if you think our low water usage will work with it. The Fleck 7000SXT valve looks good. I downloaded the Fleck 7000SXT spec sheet and they have a high flow piston option rated at 35gpm continuous to 46gpm peak with a 25psi drop. The average SFR for the 2.0 and 2.5 systems seems to be around 18 to 20gpm with a 15psi drop. From what I have been reading, the pressure drop only comes into effect once you max out the gpm rating. So is there any noticeable pressure drop running below the SFR?

    I am new to water softeners and haven't a clue how to program it yet so please bear with me. If for example I order a 80000 grain capacity unit, you guys are saying to keep the 2.5cuft of resin in it and tell the 7000SXT that I have 25600 grains and something like a 4lb or 6lb per foot salt dose?

    I read that ideally you want to regenerate every week and that longer periods can cause problems like build up on the resin, channeling, compaction. If my system requires regeneration once every 2 weeks will I run into any of these problems?
  5. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,828
    Location:
    Ontario California
    Regeneration frequency is not an issue in residential applications. Consider the millions of non electronic systems that do not have an over-ride feature that only regenerate every month or so, large systems on houses with only 1 or 2 people in them. Also consider the huge amount of portable exchange tanks out there that are only serviced once every month or two, these have never been an issue. If you are dealing with iron or manganese, then more frequent regenerations become important, but for most applications, regeneration frequncies of every few weeks is no problem.

    The high flow piston is not necessary on a smaller system like the 2.5 Cu. Ft. but there is also no drawback to it either.

    The ratings you see online are theoretical maximum capacity ratings. This can only be achieved by wasting huge amounts of salt. The maximum recommended setting for a softener is about 8 pounds of salt per cubic foot, giving the system a good mix of high quality soft water, and decent efficiency. Lower salt setings down to 4 pounds of salt per cu. ft. will give you better efficiency, and very slightly lower quality water. higher Salt settings will give you much lower efficiencies, and a very slight increase in water quality.
  6. devsd

    devsd New Member

    Messages:
    10
    Location:
    California
    Now that I know which softener size to buy for my flow requirements, I got to checking my city water chlorine levels which range from .3 to 3 averaging 2ppm according to the city. My test showed 1ppm. Most of the carbon systems I have looked at have poor flow rates. I suppose I could parallel a couple of the large carbon filters to get the required flow but wanted to ask if there are any options that might work better?
  7. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,828
    Location:
    Ontario California
    Carbon flow rates are rated for VOC, thm, organics, etc. Chlorione removal is easy for Carbon, you can achiieve the same flow rate as you can a softener with a carbon tank as long as you are not certifying it for >95% removal of organic compunds etc...

    Dont worry about the specifications on carbon for your application. Just simply match the systems. Many of our customers have great success with as little as .5 Cu. Ft. of GAC media for whole house applications. These can be stacked on top of the standard softener tanks for space savings.
  8. devsd

    devsd New Member

    Messages:
    10
    Location:
    California
    Thanks, when you say match the system, you mean get the same Fleck 7000SXT with a 13x54 tank for the GAG media? Would you recommend .5cuft for my system?

    I notice you are in California, can you tell me where your company is located?
  9. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,828
    Location:
    Ontario California
    The stacked tank designs are popular up to 2 bathroom houses. After that, dual tank systems are recommended.
  10. devsd

    devsd New Member

    Messages:
    10
    Location:
    California
    I'm looking at a Fleck 7000SXT 2.5cuft 13x54tank CS-HAC backwash system which is rated at 10gpm/cuft. 25gpm seems sufficient and maybe more with a 1 1/4 inlet, but I'm wondering if these are real world numbers or does it degrade quickly between backwash's.

    Oops 10gpm is the backwash rate, it's 5gpm/cuft service flow which would be marginal.
    Last edited: Jan 10, 2014
  11. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,828
    Location:
    Ontario California

    Service flow rate is for total reduction of listed contaminants, chlorine is one of thousands of contaminants that GAC can remove. Chlorine is one of the easiest contaminants for GAC to remove, I have tested 1/6 Cu. Ft. GAC systems at 10 GPM and still get over 95% chlorine reduction.

    The GAC bed should last for 15-20 years in your application, but we usually receommend changing it every 5-10 years for sanitary reasons.
  12. devsd

    devsd New Member

    Messages:
    10
    Location:
    California
    Thanks, I think that cleared up my confusion. I assumed the gpm rating of a GAC system was based on how fast water at maximum pressure would flow through the carbon media and out of the tank. Instead you program the Fleck valve to restrict the water flow to give it enough time to interact with the carbon and clean all the rated chemicals to the desired levels, or in my case, just clean the Chlorine at a higher gpm. I hope that's right?

    So am I overkill with a 2.5cuft GAC system? Just want the carbon system to clean my chlorine (2ppm average) and flow a little more than a 2.0 or 2.5cuft softener.
  13. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,828
    Location:
    Ontario California
    The valve does not restrict the flow to a set level. You size the equipment to meet the applications needs. In your case, because of the large number of bathrooms, fixtures, etc. a larger system that has less potential flow restrictions is desirable. I have been to houses with 10 bathrooms and a tiny little softener for 10 years, no complaints, but these houses were rarely if ever occupied.

    You could probably go with a slightly smaller GAC tank, but since the systems would look much better being the same size, and te cost difference should be minimal, it is what I would recommend.
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