Originally Posted by

**abernat**
'nother water softener sizing question.

We have an old softener that's on its last legs. As a reasonably handy homeowner I'm looking to replace it. I looked at Gary's web site for sizing but the numbers I'm getting are... odd. Can someone double-check these for me?

1) Hardness. I live in Madison, WI, and the water reports for the municipal water are:

Hardness - 17gpg

Iron - 0.20 ppm

Manganese - 14 ppb; I assume that's 0.014 ppm?

So that would give an adjusted hardness of (17) + (2*0.2) + (4*.014) ~ 17.5 ~ 18 grains, right?

2) Water usage. From our water bill we use 178 gallons per day, so that's 178 * 18 = 3,204 grains per day, and over 8 days that's 25,600 grains. Now some of that water is unsoftened, but would we want a 24k or 32k capacity?

3) Resin tank size. We have two baths, two kitchens (a 2-flat), one dishwasher, and one front-loading (so theoretically low flow) clothes washer. From the 1997 UPC (which Madison follows) I get an estimated 17 gpm, which seems high. This is from:

2x bathtubs = 8.0 wsfu

2x lavatories = 2.0 wsfu

2x HET = 5.0 wsfu

2x kitchen sink = 3.0 wsfu

1x dishwasher = 1.5 wsfu

1x clothes washer = 4.0 wsfu

1x hose bibb - unsoftened = 0.0 wsfu

Total = 23.5 wsfu ~ 17.0 gpm

I take it those numbers are assuming some average use. We rarely use the tubs and have low-flow showerheads; also, a front-loading washer. Do either of those affect the flow rate?

Anyway, as an exercise, if I use the numbers as given I get the following:

Resin: 2.5 ft^3 for 17gpm SFR

But using the hardness/salt calculation as given on Gary's site I get 1.5 ft^3 for ~30k grains of hardness.

So which would we use? 1.5 or 2.5 ft^3?

Thanks!

... as a note, if you misread the water report as manganese in parts per million instead of parts per billion, you get _really_ hard water.

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