The box says one thing. The standard says another.
One buying question per page. The answer first, in plain language — then every source it came from, linked, so you can check us. Mostly we just read the test procedure that the number on the packaging came from.
Latest verdicts
3 total-
Every 1500-watt space heater produces exactly the same heat
VerdictNo. A 1500-watt electric heater converts essentially all of that electricity into heat, so every one of them puts out about 5,100 BTU per hour regardless of brand, price, or the word on the front.
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The dehumidifier didn't get weaker in 2019. The test did.
VerdictBecause the government changed the test, not the machines. From June 2019 portable dehumidifiers are tested at 65°F instead of 80°F, to reflect the cool basements they actually get used in.
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Air purifier room-size claims quietly assume you'll accept dirtier air
VerdictWork from CADR, not from the square footage printed on the box. AHAM's certified room size assumes 4.8 air changes per hour and works out to smoke CADR × 1.55 square feet — which is the same thing as the rule of thumb that CADR should be at least two-thirds of your floor area.
Reversals
where the common advice is wrong-
Every 1500-watt space heater produces exactly the same heat
VerdictNo. A 1500-watt electric heater converts essentially all of that electricity into heat, so every one of them puts out about 5,100 BTU per hour regardless of brand, price, or the word on the front.
-
The dehumidifier didn't get weaker in 2019. The test did.
VerdictBecause the government changed the test, not the machines. From June 2019 portable dehumidifiers are tested at 65°F instead of 80°F, to reflect the cool basements they actually get used in.
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Air purifier room-size claims quietly assume you'll accept dirtier air
VerdictWork from CADR, not from the square footage printed on the box. AHAM's certified room size assumes 4.8 air changes per hour and works out to smoke CADR × 1.55 square feet — which is the same thing as the rule of thumb that CADR should be at least two-thirds of your floor area.
Why this site exists
Search for anything worth buying and you get a wall of pages recommending the same five products, none of which the writer has touched. The affiliate link is the point; the advice is filler.
So we picked a narrower job. Almost every specification printed on a box is defined by a test procedure somebody published — AHAM for air cleaners, the Department of Energy for dehumidifiers, UL for surge protection, the SD Association for memory cards. Those documents are free, and they routinely say something different from the marketing sitting on top of them. Reading them is the entire method.
Every claim here is attached to a source you can open yourself. When the sources disagree we say so and mark the verdict low confidence. When the honest answer is that you should buy nothing, that is what the page says — and every recommendation carries a stated downside, because one without a downside is one nobody checked.
We earn a commission when you buy through our links. That is the whole business model, stated plainly, and it does not touch what goes in the picks. Read the method.