wrote in message
ups.com...
We've just had a gas fire fitted in the living room and understand
there is a requirement for a vent. it's a victorian house which is far
from sealed and I intend to get a carbon monoxide alarm. We're most of
the way through fitting a secondary wood floor and the plan was to put
a vent into it to the underfloor cavity (we've recently made sure all
the air bricks to the cavity are clear).

So two questions:

1) Given the general draughtiness of the house do we really need the
air vent?

What is the consumption of the gas fire? Not all gas fires require vents -
only those above a certain consumption level.

2) if yes, how big. The figure of 100cm3 was mentioned but our local
hardware stores don't carry stock and the minimum order requriements
mean I'd look online. However the vents i've found (on
andyplumb.co.uk) are measured, strangely, in inches. I'm presuming
that 100cm3 does not equal a vent meauring 10cmx10cm but relates to the
size of the holes.

When I had an art-deco cast iron fireplace fitted a few years ago the inset
'decorative' gas fire required a vent and the fitter installed one by
cutting a slot into the floorboards and fitting a grille. It was terrible -
the draught coming up from the vent was like a hurricane - and freezing in
winter! In fact I would say that the amount of cold air coming into the room
from the vent was greater than the warm air coming into the room from the
fire. In the end we placed a piece of carpet over the vent and just made
sure that the lounge door was open a bit when using the fire. Never had any
problems.
We recently had a completely new contemporary fire installed (Brilliance
'slab' fire) and the fitter stated that the input was border-line for having
a vent fitted. I questioned him about the need for a vent and he pointed out
that the requirement for vents was only made in recent years and prior to
that no-one fitted them! As I was installing a laminate floor I just removed
the vent grille, placed a thin piece of aluminium sheet over the slot, and
laid the laminate flooring over it. Again the fire works fine, no evidence
of fumes coming into the room, and with the lounge door left slightly ajar,
plenty of fresh air to feed the fire.
If you are going to fit a vent into the underfloor cavity then I would think
strongly about ways of preventing draughts - on windy days it will be
horrendous!

Kev