On Dec 1, 12:09 pm, wrote:
While I share your concerns about them generally, this point is not
accurate. People have been using unvented gas and paraffin fires for
many years with no catalysts, and though not risk free, lack of
catalyst does not result in death. NT

More here;
http://www.diynot.com/forums/viewtopic.php?t=70741

BG won't install, service or repair them.
ARGI has advised members not to istall or service them.
Many RGIs won't deal with them.

From that thread;
"Most seem to require a permanent 100cm vent.......which will let in a
hell of a draught......so people will block them. I spend a
considerable amount of my time unblocking vital airvents blocked by
tenants, so don't tell me it won't happen cos it will."

If installed correctly you introduce a permanent 100cm2 draught; hardly
energy efficient. And no, I really can't be arsed to check the figure
quoted.
If installed incorrectly, or if they malfunction, then they are unsafe

People have been using unvented gas and paraffin fires for
many years

True They also had leaky, draughty windows, walls and floors. They had
chimneys.

We have uPVC windows & doors, draught-proofing, sheet flooring
(laminate or laminated timber), gypsum plastered walls & ceilings, and
caulking to fill any remaining gaps. Some houses are getting pretty
airtight. Introducing a 2.6kW open flame into some such houses is
bloody ignorant.

Far more sensible to use a fanned flue boiler that draws the cold air
necessary for combustion from outside only as it needs it and which
deposits the products of combustion back outdoors.

I've been in various buildings
that used simple old non vented gas burners, and have always walked out
alive.

You did. So did I.
The lady who was killed by her flueless gas fire didn't and many more
will follow; or not follow.