boiler issue

[Cuprager]

Hey all,

We have a worcester bosch combi boiler, I cant remember if this is the correct term but it is 'open flued'. I.e. the boiler has a grille on the front that sucks air in to burn (i think) the gasses are then expelled up through a flue and out the roof. The problem that we are getting is that on a windy day (fairly strong winds mind you) a smell from the boiler is blown back into the room - this only happens when the boiler is working hard due to someone being in the shower. What I am imagining is happening is that the force of the wind is greater than the pull of the flue and is forcing some of the exhaust gasses back down the flue and into our room. Any solutions that you could recommend? Someone at work has mentioned a 'granny' which i believe is a thing that sits at the top most part of the flue and spins in the wind - presumably causing the flue to 'draw' more.

Thoughts?

Gerry

[sPoNiX]

Check that the cowling on the top of the flue pipe hasn't been disloged/damaged.

Also check that the wall vent in the kitchen hasn't been blocked.

sponix

[Christian McArdle]

Whatever you decide to do, I'd get a carbon monoxide detector. Your current situation might actually be dangerous if flue gases are being blown back into the boiler.

Christian.

[john]

Definitely dangerous and get a detector.

Possibly the 'draw' up another chimney or vent is more powerful and is reversing the flow of the flue. Is there the recommended size of fresh air inlet into the room in which the boiler is located?

Get a CORGI person to check it. Mine has been condemned - although it met the original regulations it does not meet the revised ones and I have to create more ventilation.

John

[John]

If it ever worked satisfactorily without downdraught causing spillage there must be some reason why you have a problem now. Has the combustion air supply been restricted somehow, has the cowl or the flue pipe been damaged, Have any trees grown up to cause a pressure zone with an adverse wind, Has a building been erected or modified to cause a pressure zone?

[Cuprager]

Thanks for your input so far everyone.

To answer a few questions...

The boiler is in a utility cupboard that is very large. This cupboard has louver doors that open out onto a large room. There has been no changes that i can see either with the flue pipe or cowl. There is no blockage at the boiler end (that i can see). The flue pipe goes straight up through the attic space and out through the roof so is in very open space. We have a carbon monoxide detector - a Kidde one that talks. It has went off once when there were high winds and the shower was in use.

[john]

How is the room ventilated to the outside? If it isn't then the opening and closing of doors in the house will affect it. The combustion air has to come from somewhere. Get it checked.

[john]

The manual for mine refers to "Air direct from the outside" This implies you should have a duct going through the wall.

John

[Cuprager]

The room is not ventilated to the outside as such, it is a dining room which has a window but as you can imagine thats not open too often these days.

Incidentally the boiler has been in its present location for about 20 years with no trouble. It was serviced just before the winter and the engineer did not have any concerns about it. He did a smoke bomb test to ensure that the flue was pulling and it was ok.

[Cuprager]

Mine has an open grille on the front that takes air from the room... the only connection it has to the outside id the flue pipe. There is a name for this type of boiler but i have forgotten it! (cue amusing names!) It is a worcester heatslave 9-24 for info.

[john]

Mine passes the spillage test but I still get a condemned notice as it needs more direct ventilation. It is a Worcester Heatslave Hi-Flow (made 1987). The manual says: "6. If installed in a room it must have a permanent air vent either direct to outside air or to an adjacent room which itself has a permanent air vent to outside air. The minimum effective area must be 100cm squared."

For air to go up a chimney air has to enter to room somehow. A friend has just had to have a vent fitted in a wall despite pleas that they leave a vent on the patio door open.

[john]

Name - "Open Flued" ???

[Cuprager]

Thats interesting, I have a vent on the ceiling of the room that the boiler is in, it vents into the communal attic space so i doubt it counts for a lot.