Gas Boiler Vent query

We have just moved house and have started doing some work.
The gas central heating boiler is in the kitchen and has a flue pipe from it going into the wall and up out the chimney.

The back door has a vent (30mmx10mm) and the window has an expelair type vent.

I have just replaced the kitchen units and have built a shell unit round the boiler as its looks spoil the kitchen. The 'shell' is 2m high, has sides and doors, but no base, shelves or top. There is a gap of 10mm between boiler and side panels. The shell can also be easily removed for boiler service etc.

I have today had the windows and back door replaced with PVC, and therefore now have no vents.

The windows fitters have told me that I need to have extra vents as the flue only is not enough.

Is this true?

If so, can I just put a grill on the ceiling above the boiler and have a flexi-hose to the outside?
OR, must the vent be down at boiler or floor level?

Any assistance here would be most appreciated.

IanS

I think the answer to your idea is no, but take a look at
http://www.glidevale.com/pages/pds/cbair.html

Ive never heard of anything like that. My boiler is also boxed in and although we have vents above the doors and window they have always been in the closed position and there has never been any (condensation I assume) problems.

I think it may also be to do with carbon monoxide, since it is colour and odor less you must have a vent to remove it.

Could you not put a vent through the wall as it shows in the link?

The outside wall of the kitchen is all window/door so can't just use a though-wall vent as in the link.

I will just go for a grill in the ceiling above the boiler with a flixi-hose to a vent in through the soffits.

Better to be safe than sorry

Many thanks for the responses. Keep up the good work.

IanS

If you have a standard flue, as opposed to a balanced flue, your boiler needs air for combustion from the room it is in.
Too little air coming in = too much carbon monoxide.
NB an expelair type removes air, your boiler needs an incoming source of air.
Don't gamble with your life. Get vented.

Mrpym beat me to it. Don't kill yourself and your family.

I had a similar problem in the last two houses. Both times with living room gas fires. The Gas Board threatened to cut off the gas unless I had vents fitted to the room door AND to the front door. This was to let fresh air be pulled IN as the boiler behind the gas fire vented gasses OUT up the chimney. If air can't come in, the gasses can't go out (otherwise you'd create a vacuum). So the gasses gradually build up, backflow into the room and kill you. Having an "Expelair" fan produces an interesting complication!

I didn't want vents in the doors so I looked for an alternative solution. My solution for the first gas fire (in a room with concrete floors) was to have a local company make a metal duct that went from a hole bashed in the side of the chimney breast (at floor level) along the skirting board (removed) to a vent in the nearest outside wall. I then had cupboards built over the duct to hide it. (The "carpenter" made a right pig's ear of it and I ended up remaking the cupboards myself).

The second fire was easier as the room had floorboards with a 12" gap beneath. I simply cut a rectangular hole in the floorboard close to the wall-mounted fire (and partly beneath it) then fitted a nice grill over the hole, holding the cut edges of carpet down.

I used a similar solution for the separate gas boiler situated in a cupboard.

So, look to see where you can fit a vent as low as possible (and away from the Expelair fan!) Its cross-sectional area is governed by the boiler rating so seek advice. I seem to recall that my little boiler required 20 square inches. Shape doesn't matter - so it could be a 1/2" slot forty inches long if necessary! Put it as close as possible to the boiler or you'll feel the cold draught.