Humidifiers / Honeywell
Honeywell HWM845B Filter Free Warm Mist Humidifier
Genuinely sterile boiled steam for $55, and a scalding chamber to go with it.
Overall score 6.4/10
Pros
- + The vapour is genuinely sterilised by boiling — no white dust and no aerosolised tank bacteria, unlike any ultrasonic here
- + No fan means no fan noise; for a light sleeper this is quieter than any wick or ultrasonic unit in this set
- + Truly filter-free — there is no consumable you are required to buy, which over three years undercuts the evaporative units badly
- + Three-year Honeywell warranty at $54.95, and a wide tank opening you can get a hand into
Cons
- − It boils water in a child's bedroom; Honeywell's own manual warns the steam "can cause burns" and to keep it away from children
- − No humidistat whatsoever — two knob positions and nothing that senses the room
- − Weekly vinegar descaling is not optional: mineral scale on the heating element is what kills these units, and Honeywell's manual prescribes the routine
- − Retail listings disagree on coverage — 400 ft² at Walmart versus 520 ft² on office-supply listings for the same SKU — and Honeywell publishes no number at all
- − No published output figure, so the only throughput data point is a 1-gallon tank over 24 hours on low
Honeywell HWM845B Filter Free Warm Mist Humidifier review: what the specs say
Genuinely sterile boiled steam for $55, and a scalding chamber to go with it. At $54.95, Honeywell's 2018 model sits in the middle of the range — the humidifiers we compare run from $19.79 to $299.99. It scores 6.4/10 overall, calculated from published specifications across 8 categories rather than from a subjective impression.
Its strongest showing is Freedom From White Dust at 10.0/10 — the thing marketing never mentions. Ultrasonic humidifiers aerosolise whatever is dissolved in the water and deposit it as white dust on furniture — the EPA notes they are 'very efficient at dispersing minerals in tap water into the air', along with microorganisms from the tank. Evaporative and boiled-steam units do not do this at all. A high score means the technology cannot produce dust; a low score means you are buying distilled water for the life of the machine.. The weakest is Humidity Control at 2.5/10, which is the trade-off to weigh before buying: if that is the specification you care about most, one of the alternatives below will serve you better.
Worth knowing before you buy: it boils water in a child's bedroom; Honeywell's own manual warns the steam "can cause burns" and to keep it away from children; and no humidistat whatsoever — two knob positions and nothing that senses the room. Every specification on this page comes from Honeywell's own documentation or a verified retail listing — where a figure is not published, the table says so rather than estimating it.
Specifications and price last verified . Report an error
Full Specifications
| Humidification Technology | Warm mist — Honeywell's manual: "The tank feeds water into the boiling chamber where it is heated to a steam vapor". A resistive element does the boiling; there is no fan and no wick |
| White Dust & Mineral Aerosol | None. Boiling leaves minerals behind as scale in the chamber rather than aerosolising them, which is the whole reason warm-mist and steam units are dust-free — and also why the chamber needs descaling |
| Tank Capacity | 1 gal / 3.7 L |
| Rated Output per Day | Not published by the manufacturer — neither Honeywell's manual nor its store page gives a gallons-per-day or mL/hr figure for the HWM845 |
| Quoted Runtime (and at which setting) | "Up to 24 hours" — Honeywell's store page attaches this to the LOW of two comfort settings. On high, a 1-gallon tank boiled away goes very much faster |
| Rated Room Coverage | Sources conflict: Walmart's listing for the HWM845B says 400 ft², office-supply listings for the identical SKU say 520 ft², and Honeywell's own store page says only "medium" room |
| Humidistat | None. Two fixed comfort settings on a knob, no humidity sensor, no auto mode. There is an auto shut-off for an empty tank, which is a safety cut-out and not humidity control |
| Noise | Not published as a decibel figure. There is no fan, so the only noise is the boil itself — genuinely among the quietest ways to humidify a bedroom, at the cost of the heat |
| Filters & Cartridges (Annual Cost) | Nothing is required — it is filter-free. Honeywell offers the optional Protec PC2V1 antimicrobial cleaning cartridge on a 30-day cycle (roughly $20-30/yr if you use it), but the unit runs without it |
| Cleaning Burden & Dishwasher-Safe Parts | Honeywell's manual says "Weekly cleaning is recommended" and prescribes two cups of distilled white vinegar in the reservoir for 20 minutes to strip scale, plus a separate bleach disinfection. The tank opening is wide; nothing is dishwasher-safe. Skip the descaling and the element fouls and output collapses |
| UV / Antimicrobial Claim | Boiling is the kill stage — no UV lamp and no antimicrobial wick. The optional Protec cartridge is a tank-side cleaning aid, not a certified disinfection claim |
| Mist Temperature & Burn Risk | Boiled. Honeywell's manual is explicit: "DO NOT touch the steam vapor. Steam can cause burns" and the unit "produces hot steam". The output is genuinely sterile; the trade-off is a reservoir of near-boiling water in the room |
| Connectivity | No wireless connectivity — illuminated power switch and a two-position knob |
| Material | Plastic housing with a metal heating element inside a sealed boiling chamber |
| Warranty | 36 months |
Compare Honeywell HWM845B Filter Free Warm Mist Humidifier With
Cheaper Alternative
Pure Enrichment MistAire Ultrasonic Cool Mist Humidifier (PEHUMIDIF) — $39.99
Premium Alternative
Honeywell HCM350 Germ Free Cool Mist Humidifier (HCM350W / HCM350B) — $89.95