Air vent for Saunier Duval 223C Gas boiler

[BobDee]

Our French home has a 20 year old Gas Boiler which works fine. My question is, does this type of bolier need an air vent in the same room? There is a hole in the wall with a plasic grill just above floor level, which I had assumed was for the boiler, but having current problems with cold air from this vent actually freezing the cold water pipe that runs immediatly below it, I'm looking at alternative ways of venting the boiler if it actually needs a separate air supply. I have the original installation instructions for the boiler and can see no mention of an air vent requirement. It may be that the hole in the wall was for a dryer and nothing to do with the boiler. Any ideas any one?

Regs

BobDee 

[Gyn_Paul]

Is this vent the sole source of air into this room? Does the boiler have a standard flue or a 'ventouse' (sp) ? That is, a balanced flue which is a pair of concentric pipes where the flue gasses flow out along the centre tube (either naturallly or fan-assisted) and the fresh air required for combustion flows in along the outer 'sleeve'. The boiler itself is sealed from the room which - as far as I'm aware does not require ventilation.

If the air for combustion comes from the room itself (i.e. if the burner isn't sealed from the room) then that ventilation is ABSOLUTELY VITAL,  not to say a legal requirement and must not, on any account, be obstructed.

Insulating or re-routing the pipe, or cutting another vent of at least the same dimentions, are your only practical alternatives.

p

[BobDee]

GP. Thanks for the response. The boiler dosn't, as fas as I can see have a double flue system. It looks like a single pipe. The room is a utility room with obviously a window and the only ventilation is into the main house via a normally open door. I fully understand the importance of ventilation of gas appliances, but cant understand why the installation instructions make no mention of ventilation requirements. Could the 223c be somehow self ventilating? Its just been in the recent cold weather that the frozen pipe situation has arisen. The vent is behind a washing machine at virtually floor level and I am thinking of fitting a deflector to the base of the vent to stop the airflow from directly hitting the water pipe below it. Cant understand why it didnt freeze last winter, All I can think of  is that I now have a sheet of cardboard under the washing machine (to make it easier to move), and this is preventing the normally warm room air from getting to the water pipe.

BD

[Gyn_Paul]

BD. Tell us more about the flue pipe... what sort of diameter are we talking about? does it go horizontally through the wall to a terminal or does it go up and out the ceiling/roof? balanced flues are almost always horizontal, while naturally ventilated boilers have to have a vertical flue.

Do you have enough space behind the washing machine to spray the pipe with builder's foam? That insulates brilliantly, and once it's set properly can be cut to shape.

p

[BobDee]

Hi Paul, Hope the name is right!. The flue is vertical, about 5 inches in diameter and has a "rain hat" at the top. Its only a bungalow so its no great length. It looks like a simple cylinder with no double skin that I can see but then unless I get onto the roof its pretty hard to be sure. I reinsulated the pipes under the air vent the first time they froze about three days back, using that self adhesive aluminium backed foam tape stuff. Looks neat but probably not the best way to do it. I like the idea of the foam solution but there are two gas taps in the same pipe run that that would have to be masked out. Some form of baffle on the outside that would still let air in but stop the direct freezing draft might also be a possibility. It could be that because the boiler is so old, there was not the importance attached to air venting in the 1980's. I never remember air vents for gas fires and ascots when I was a kid.. (talking 50's now!)

BobD

[Gyn_Paul]

[quote user="BobDee"]

Hi Paul, Hope the name is right!. The flue is vertical, about 5 inches in diameter and has a "rain hat" at the top. Its only a bungalow so its no great length. It looks like a simple cylinder with no double skin that I can see but then unless I get onto the roof its pretty hard to be sure. I reinsulated the pipes under the air vent the first time they froze about three days back, using that self adhesive aluminium backed foam tape stuff. Looks neat but probably not the best way to do it. I like the idea of the foam solution but there are two gas taps in the same pipe run that that would have to be masked out. Some form of baffle on the outside that would still let air in but stop the direct freezing draft might also be a possibility. It could be that because the boiler is so old, there was not the importance attached to air venting in the 1980's. I never remember air vents for gas fires and ascots when I was a kid.. (talking 50's now!)

BobD

[/quote]

Ah yes but we're talking a housing stock which leaked

like a sieve... The external door to our back kitchen (which is where our

Ascot water heater was: marvellous device, little control on the front labelled

'warm - hot - boiling' the latter setting delivering water quite near enough to

boiling to make a proper pot of tea) had a gap at the bottom fully big enough

to roll a pencil under it!

Plus it was town gas generated from coal; largely hydrogen.  I have an

idea that incomplete combustion of this mixture was less lethal than the

methane majority mixture from the North Sea,

although this is hazy and I may be completely wrong (Punch or one of the others

will be sure to tell me if I am). I do remember it was lighter-than-air,

though and that it was possible at school to fill a bin-bag with gas, seal up

the end with a lit fuse of some description, launch it out of the science lab

window, watch it sail across the quad and then ignite like a Zeppelin above the

heads of the 1st formers below !

Happy(ish) days !

Anyway... It looks to me that you have a flue classique which does require

the fixed external ventilation. Any chance you could cut another vent in the

wall nearer the boiler and further from the susceptible pipework?

[Le Plombier]

I assume your boiler is not is the Kitchen with a gas cooker, if it is it is a completely different ball game

Provided it is located ouside the Kitchen you need

No ventialion if it is ventouse (balanced flue)

A low level vent no more than 300mm above the floor with a free area of 100 cm square, a 125mm dia pipe with matching grilles will be adequate, if it has a normal single wall chimney. This I think will be your situation.

If it has no flue ( unlikely ) throw it away before it kills you

If you block the vent and die as a result you do realise that the installing plumber will probably be charged with manslaughter, hardly fair on him when he installed the vent with good intent. People blocking off vents is a problem out here. I have refused to complete gas installations before now because clients have refused to allow me to install a vent

When it comes to gas vents are there for a purpose

I am gas qualified but it is difficult to advise without a survey of the property, I do not wish to survey your property but I suggest you find someone professional local to you to advise you and make sure you are in compliance with the gas regs and , most importantly safe.

Le Plombier