What to look for inside a vacuum cleaner before you buy it
Vacuum cleaners are sold on suction figures and on how they look in a showroom. Neither tells you much. What matters is airflow, sealing, and whether the parts that wear can be replaced.
Suction and airflow are not the same thing
A high suction figure measured at a blocked inlet tells you the motor can pull hard against nothing.
What actually lifts dirt is airflow, the volume of air moving through the head and along the floor. A machine can have impressive suction on paper and poor airflow in practice if the path is narrow, restricted, or leaking.
Nobody prints airflow prominently, which tells you something.
The practical test in a shop is to put your hand over the end of the hose with the machine running and then release it. You want a strong, immediate rush of air, not a wheeze.
Sealing
This is the one people never think about and it decides whether the machine helps or harms the air in your house.
A vacuum draws air through a filter and pushes it out. If the body is not sealed, some of that air escapes before the filter, carrying fine dust with it.
A sealed system with a good filter captures the fine particles. An unsealed one with an identically good filter blows a proportion of them back into the room.
Look for a claim about a sealed system, and look at the joins and the way the dust container latches. A container that feels loose in the shop is not going to seal better after two years.
The parts that wear
Belts, on machines with a driven brush roll. Ask whether the belt is user replaceable and what it costs. Some are a two minute job with no tools, some require dismantling half the machine.
Brush roll bearings. Turn the brush by hand and feel for roughness.
Filters. Find out how many there are, whether they are washable, how often they need replacing and what they cost. Some machines are cheap to buy and expensive to own for precisely this reason.
Hoses and wands, which crack at the ends. Check they are sold separately.
Battery, on cordless machines. This is the whole question for a cordless vacuum. Is the battery replaceable by the owner, what does it cost, and is it still made? A cordless vacuum with a sealed battery has a fixed lifespan and that lifespan is shorter than you think.
Bagged or bagless
Bagless saves you buying bags and it is dirtier to empty, because emptying releases fine dust exactly where you are standing.
Bagged costs a little each year and contains the dust completely. For anyone with allergies I would take bagged every time.
Neither is more reliable than the other in my experience.
Weight and the head
Pick it up. Carry it a few steps. Push it across whatever flooring the shop has.
A machine you do not enjoy using does not get used, and that matters more than any specification.
Look at the head. Can it get under furniture. Does the brush roll turn off for hard floors, because a spinning brush on a hard floor flings debris. Is the head height adjustable for deep carpet.
What I would actually buy
A mid range machine from a brand with parts available, bagged if anyone in the house has allergies, with a replaceable belt and a washable pre filter.
Not the cheapest, because the cheapest ones use small motors, unsealed bodies and non replaceable parts.
Not the most expensive either, because past a certain point you are paying for a lighter body and a nicer finish rather than better cleaning.
And whatever you buy, change the filter on schedule. A clogged filter kills airflow, the motor works harder and runs hotter, and a motor that has been running hot for a year is the machine that comes into my shop dead at three years old.
