Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Why?

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!

HEPA stands for High Efficency Particulate Air. It's simply a finer mesh so
it traps smaller particles, typically 99.95% efficient in removing particles
down to 0.3 micron. A human hair by comparison has a diameter of 60 -90
micron.

Is HEPA a registered trademark?

Not as far as I know, more an internationally agreed performance standard.
Vacs for asbestos work to similar standards.

is the HEPA filter on a vacuum cleaner likely to need replacing more
often than non-HEPA on account of the greater dust it traps?

Yes sort of. HEPA's are more commonly found as final exhaust filters, the
main filters trap the majority of the dust, leaving the HEPA to filter only
the finer particles.

Can a HEPA filter be washed or otherwise cleaned so that it can be
reused? Or is the life of a HEPA filter so long that this is not a
consideration.

You can't wash then, but they last a reasonable time (see above).

Considerable benefits if you suffer from asthma, but they also reduce
airbourne dust to almost zero, so you don't have to dust so often.

--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257