8 gpg and 7000sxt - tank size

[RinHouston]

I have been researching softeners and figured I should go with a 7000sxt for the flow rate. We have a 1" copper service into the house. The house is 5 bedroom, 4 1/2 bath, with the wife and 2 girls was figuring a little higher than normal water usage. I measured the flow at the hose bib that comes off right where the service comes in and it does 18+ gpm even through the 1/2" drop to it. The static water pressure is 64#. The master tub flows 9 gpm, with the showers all at 2.5 gpm. The test water hardness is 8 gpg on city water. The house is about 10 years old and has lots of calcium build up on the fixtures and shower. The sizing calcs show I could use as small as a 24,000 grain unit. But, that seems very small for the house size.

From what I have read, I would be better off going with a 48k system and the 7000sxt to make sure we have the flow with minimal pressure drop. Is that going to create channeling problems or too long regen times? Should I plan for something else?

Thanks for the help.

 

[ditttohead]

Smaller tank sizes have their own unique potential long term problems. Primarily excessive flow through the resin bed. For your house size I would recommend a 2 cubic foot 7000SXT. Simply run it at lower salt settings and you will be just fine. The system should regenerate no less than monthly. You will read on some postings that more frequent is necessary... this is true in certain circumstances, but on municipal supplies it is not critical. As a point of reference, my Moms house currently regenerates monthly but only due to the override feature of the 7000. Her system is 2.5 cubic feet (sized for when there were 5 people in the house), and her hardness is only 6 grains. She is currently the only occupant, and it has been going like this for a decade... no problem.

 

[Sponsor]

 

[Bannerman]

A 2 cu.ft softener to which Dittohead refers, totals 64,000 grains capacity.

Softeners should not be setup to utilize the entire capacity of the device as exhausting the total resin capacity requires 15 to 18 lbs/salt per cu/ft of resin to regenerate - which is very poor salt efficiency.

For example, to regenerate 60,000 grains capacity with a 2 cu/ft softener, 30 lbs/salt is required which equals only 2,000 grains/lb.

A 2 cu/ft softener set to regenerate at 48,000 grains, requires only 16 lbs/salt which is a more efficient 3,000 grains per lb.
Greater efficiency maybe realized by regenerating that same 2 cu/ft softener at 40,000 grains as that would require only 6 lbs/cu/ft or 12 lbs total salt, equaling 3,333 grains per lb.

While even greater efficiency may be further realized, the quality of the softness of the water may suffer and, more water will be utilized to regenerate since regeneration will occur more frequently. It is generally considered good efficiency if your requirements allow using 6 or 8 lbs/cu/ft and regenerating no more than 1X per week.

Having a larger softener allows periods of increased flow volume since the additional resin provides increased surface contact area for softening the fast moving water.

 

[ditttohead]

The math

4 people x 60 gallons x 8 gpg = ≈ 2000 grains per day

A 40,000 grain system, 2 cubic feet regenerated at 6 pounds per cubic foot, (often referred to as a 64,000 Grain system) would regenerate every 20 days. Looking good!

 

[RinHouston]

Thanks for the recommendations. That is very helpful.

 

[RinHouston]

The drain will be at the washing machine which is about 27' total feet of pipe from the softener location. I planned to run 3/4" cpvc to that location. Will running 1/2" ID PE or PEX plastic tubing get the job done? That would be quicker and cheaper. I didn't want to have any problems with incomplete regen. The rise is from the softener to the 8 1/2' ceiling, then horizontal until the final drop to the washer drain.

 

[ditttohead]

Use standard 3/4" pvc. Cheap, simple, no problems.