Aprilaire 700 Fan-Powered vs Aprilaire 800 Steam
In short: The Aprilaire 700 Fan-Powered costs $810 less; the Aprilaire 800 Steam genuinely holds a larger room (8,524 sq ft against 4,434 sq ft); the Aprilaire 700 Fan-Powered costs about $3245 less a year in wicks and watts.
| Spec | Aprilaire 700 Fan-Powered | Aprilaire 800 Steam |
|---|---|---|
| Approx. price | ~$290 | ~$1,100 |
| Type | Whole-house | Whole-house |
| Mist | cool | warm |
| Rated output | 18 gal/day | 35 gal/day |
| Output standard | Maker's published output rate | Maker's published output rate |
| Honest room size | 4,434 sq ft | 8,524 sq ft |
| Claimed coverage | 5,300 sq ft | 10,300 sq ft |
| Claim vs physics | 1.20× | 1.21× |
| Tank size | Plumbed | Plumbed |
| Runtime at the claimed room | — | — |
| Real runtime at full output | — | — |
| Yearly running cost | ~$67 | ~$3312 |
| Replaceable media | Filter, replaced through the season | None — nothing to buy |
| White dust risk | No | No |
| Humidistat | Yes | Yes |
| Noise on low | — | — |
| Top fill | No | No |
| Dishwasher-safe tank | No | No |
| App control | No | No |
| Power | 145 W | 11500 W |
Highlighted cells are the better number in that row, and only where a direction is unambiguous — more output and more supported room, less noise, cost and price. Honest room size and runtime are computed from each maker’s own published figures; here is the calculation.
Pros and cons
Aprilaire 700 Fan-Powered
- The only whole-house evaporative here that can humidify when the furnace is idle, which is the specific complaint owners of bypass units raise
- No bypass duct makes it fit in mechanical rooms where a 600 will not
- Highest evaporative capacity Aprilaire makes, at $70 more than the 600
- Same $25 panel and same five-year warranty as the bypass units
- 145W whenever it runs, against 20W for a bypass unit that borrows the furnace blower
- The onboard fan is audible in a finished basement in a way a bypass unit is not
- Installation cost runs a little above the bypass models, typically $840-$1,560
- Still forced-air only - the fan solves the idle-furnace problem, not the no-ductwork one
- The 5,300 sq ft headline is for tight construction; Aprilaire's own average-home figure is around 3,000
Aprilaire 800 Steam
- The only unit here that works with a boiler, baseboards or a heat pump, because it makes its own heat rather than borrowing the furnace's
- Nearly twice the capacity of the largest evaporative whole-house unit
- No consumable pads or panels at all
- Reaches a humidity target far faster than any evaporative, which matters after a cold snap
- 11.5 kW while steaming - by far the most expensive unit here to run, and it needs a dedicated 240V circuit
- Installation of $1,800 to $4,200 on top of $1,100 of hardware, because of the electrical work
- Electrodes scale in hard water and need periodic cleaning, which is a service call for most owners
- Over-humidification risk is highest with a unit this powerful in a cold climate
- The 10,300 sq ft figure is far beyond most houses; for a normal home this is more capacity than the envelope can use