A.O. Smith AO-WH-SOFT-450T

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.

Nothing fills those gaps here. A spec sheet with holes at least tells you where to push the seller, which an invented number does not.

How it sits in the A.O. Smith range

The AO-WH-SOFT-450T is the largest A.O. Smith unit we track at 45,000 grains. Alongside it sits the AO-WH-SOFT-350: the AO-WH-SOFT-350 drops 10,000 grains on different warranty terms.

At its maximum 18.75 lb dose the AO-WH-SOFT-450T works out to roughly 2,400 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 26 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. 45,000 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.

Mistakes to avoid at this size

• Buying the number on the box. The 45,000-grain rating is what this unit reaches at its maximum 18.75 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.
• Spending the iron headroom instead of banking it. A 10 ppm rating is worth having, and the way to use it is as margin rather than as a target to run against. Iron also loads capacity: at 3 ppm you are effectively adding 12 gpg to your hardness figure before sizing, which pulls a 45,000-grain unit down a household size.
• 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.