Aprilaire 600 Bypass vs Aprilaire 700 Fan-Powered
In short: The Aprilaire 600 Bypass costs $70 less; the Aprilaire 700 Fan-Powered genuinely holds a larger room (4,434 sq ft against 4,188 sq ft); the Aprilaire 600 Bypass costs about $36 less a year in wicks and watts.
| Spec | Aprilaire 600 Bypass | Aprilaire 700 Fan-Powered |
|---|---|---|
| Approx. price | ~$220 | ~$290 |
| Type | Whole-house | Whole-house |
| Mist | cool | cool |
| Rated output | 17 gal/day | 18 gal/day |
| Output standard | Maker's published output rate | Maker's published output rate |
| Honest room size | 4,188 sq ft | 4,434 sq ft |
| Claimed coverage | 5,000 sq ft | 5,300 sq ft |
| Claim vs physics | 1.19× | 1.20× |
| Tank size | Plumbed | Plumbed |
| Runtime at the claimed room | — | — |
| Real runtime at full output | — | — |
| Yearly running cost | ~$31 | ~$67 |
| Replaceable media | Filter, replaced through the season | Filter, replaced through the season |
| 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 | 20 W | 145 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 600 Bypass
- Seventeen gallons a day for $220 of hardware is the best capability-per-dollar in the entire catalog
- So widely installed that any HVAC tech can service it and parts are on every supply-house shelf
- Aprilaire states outright that the 5,000 sq ft figure is for tight construction and about 2,000-2,500 is realistic
- Twenty-five dollars a year and one panel swap is the whole maintenance burden
- Owners report decade-plus service lives with nothing but panel changes
- Humidifies only while the furnace runs, which on mild days is not often enough
- Installation typically $700-$1,400 on top of the hardware, and it needs a drain as well as a supply
- Bypass designs waste some water down the drain by design - it is not a closed loop
- Over-humidifying a cold-climate house condenses on windows and inside walls, and there is no per-room control to fix it
- Requires forced-air heating; useless with boilers, baseboards or minisplit heat
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