BTU SizerWhat does each room need for its air?
Air quality is the one part of comfort people buy room by room, which is exactly why it ends up uneven.
One comfort check a month
MonthlyOne thing a month worth measuring, cleaning or switching over before the weather turns — the maintenance side of sizing, in two sentences. No product pitches.
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How this works
What each room needs
The three air machines sized per room, side by side, so one sheet covers a whole house.
| Room | Purifier CADR | Extractor | Dehumidifier |
|---|---|---|---|
| Bedroom, 150 sq ft | 100 CFM | — | — |
| Living room, 350 sq ft | 234 CFM | — | — |
| Bathroom, 50 sq ft | — | 50 CFM | — |
| Kitchen, 30 in hob | — | 300 CFM | — |
| Basement, 800 sq ft | 534 CFM | — | 20 pints |
A purifier is sized on floor area, a dehumidifier on dampness, a fan on fixtures. Only the first scales with room size alone.
Frequently asked questions
Why two thirds of the floor area?
It is the rule the Association of Home Appliance Manufacturers publishes, and at a standard ceiling it produces about five air changes an hour — the rate at which a purifier keeps ahead of what keeps coming into a real room.
Should I buy one big purifier or several small ones?
Several, one per space you care about. A single large machine in a hallway cleans the hallway. Within one open-plan space, a single larger unit is quieter than two small ones running at full speed.
Does the total mean anything?
As a budget figure, yes — it tells you what a whole-house plan costs in capacity. As a purchase, no: rated CADR only applies to the room the machine is standing in.