A.O. Smith AO-WH-SOFT-350

What A.O. Smith publishes, and what it does not

This record is mostly complete. What A.O. Smith omits will not stop you sizing the unit or working out roughly what it costs to run, though you will have to ask if you want the full picture before buying.

Of the specifications a buyer actually needs to size and compare this unit, A.O. Smith publishes 7 of 8. The capacity claim is backed by Efficiency rated per NSF/ANSI 44.

Not published for this unit:

• price, which left to the retailer by some manufacturers, which makes comparison harder.

Those cells stay empty in the table above. We do not fill them from retailer listings or third-party reviews, because a number nobody measured is worse than a blank that tells you to ask.

How it sits in the A.O. Smith range

The AO-WH-SOFT-350 is the smallest A.O. Smith unit we track at 35,000 grains. Alongside it sits the AO-WH-SOFT-450T: the AO-WH-SOFT-450T adds 10,000 grains on different warranty terms.

At its maximum 15 lb dose the AO-WH-SOFT-350 works out to roughly 2,333 grains per pound of salt. That figure is the fair way to line it up against other units, because every manufacturer in this category advertises the maximum and nobody runs it there day to day. Each regeneration also sends 21 gallons to the drain.

Who this suits, and who should skip it

A good fit for:

• Mid-sized households, which is where most buyers land. 35,000 grains covers a typical family without the price of the largest units.
• Well water. A published rating of 10 ppm of iron is among the higher figures we have recorded, and iron rating is the specification that decides whether resin lasts ten years or three.
• Anyone replacing an older timer softener. A metered head regenerates on water actually used rather than on a schedule, which is where most of the salt saving in a modern unit comes from.
• Tight installs. At roughly 32 inches tall this fits under low ducting and in crawl spaces where a 48-inch cabinet plus lid clearance will not go.

Mistakes to avoid at this size

• Buying the number on the box. The 35,000-grain rating is what this unit reaches at its maximum 15 lb salt dose. Day to day it runs a much smaller dose and delivers proportionally less per cycle, which is the honest basis for comparing it against anything else.
• Assuming the iron rating covers untreated well water. 10 ppm is a genuinely high rating, but it is a ceiling rather than a target. Sustained iron near that limit still shortens resin life, and above roughly 3 ppm a dedicated iron filter ahead of the softener is usually the better build.
• Sizing from the house instead of the water. Capacity needed is household size multiplied by hardness, so two identical houses on different water need different softeners. Test the water first, then size to the result.
• Comparing it on price you cannot verify. A.O. Smith leaves pricing to the retailer on this unit, so the figure you find will move week to week and between stores. Price it in the same week you price its alternatives or the comparison is meaningless.