Log burner condemned by the weather is this possible?

Hopeforananswer

A log burner was fitted in my home in a room with a cooker hood extractor fan that is fed to the outside. At the time of the fitting the engineers have stated a smoke test was carried out with the extractor switched on as detailed in the quote, although this was not witnessed. 18 months later a service has been carried out, the engineer has stated the fire is in excellent working order and the chimney was clean. However the smoke test failed when the extractor fan was turned on as smoke was clearly visable - so the fire has been condemned. As there in no change to the room or fittings in the room the only explanation we have been given is the weather or the air pressure. We have checked the weather on the installation date and on the service date and there was nothing significant or extraordinary on either date in the weather. Is this explanation feasable?

savemoney

I never heard of a log burner using a cooker extractor fan. I thought that wouldnt be suitable at all. Surely the instakllation should have been checked by a HETAS installer. I had a log burner for 8 years and never had any problems with weather at all.

Hopeforananswer

Sorry, obviously my post is not clear - the room is a kitchen/diner + sun room all open plan, the extractor fan is over 6 mtrs away from fire but still caused smoke to be pulled from burner.
Thanks for responding

Alex1983

The extractor sucks air out the room which can create a reverse flue, this is why it needs testing with extractors on. We do the same with gas fire installations.

Not the same as a log burner but when we service gas fires on damp still days sometimes it will fail a smoke test and we need to warm the chimney up for up to 15mins before it will pull properly, so on that logic in may be possible for weather to have a effect on the smoke test. This is an assumption though, in gas safe not hetas and do not work on log burners.

suki1964

I've worked in a pub for years which has a log burner in the bar

That can not be lit if the connecting doors from the kitchen to the bar are open, the extractors in the kitchen will pull the fire causing the bar to fill with smoke

Gloomendoom

I had the same problem. A previous owner had installed an extractor fan in the kitchen that would not have been out of place powering an aeroplane. When it was on, it dragged the smoke back down all the chimneys in the house.

I got rid of the fan.

FreeBear

Didn't think you were allowed to fit a stove in a room that also had an extractor unless the stove was room sealed (i.e. drawing air in via ductwork from outside).

Does the stove have the option for ducting air in from outside ?

Furts

Alex1983 wrote: »

The extractor sucks air out the room which can create a reverse flue, this is why it needs testing with extractors on. We do the same with gas fire installations.

Not the same as a log burner but when we service gas fires on damp still days sometimes it will fail a smoke test and we need to warm the chimney up for up to 15mins before it will pull properly, so on that logic in may be possible for weather to have a effect on the smoke test. This is an assumption though, in gas safe not hetas and do not work on log burners.

I have experienced chimney problems with cold flue liners and cold days. Things seemed fine on a warm, summers day. I too am not hetas, I am just a simple building type. But OP's situation puzzles me. If we were talking about a gas fire there could be an airbrick to give fresh incoming air. Hence if the extractor fan was switched on one would expect to draw air from here. My intuition is the room design, and ventilation is wrong. Put differently, it is apparent the air feed to the log burner is not correct.

Davesnave

FreeBear wrote: »

Does the stove have the option for ducting air in from outside?

^ This.

But even if it doesn't, a duct ending close by might well be enough to swing the balance on bad days.

ComicGeek

Furts wrote: »

My intuition is the room design, and ventilation is wrong. Put differently, it is apparent the air feed to the log burner is not correct.

Probably combination of poor air feed to the log burner and poor replacement air feed for the kitchen extract fan. Both systems will pull air in from the path of least resistance, so normally you would have to have local air vents adjacent to each to prevent the current problem.

No mention of whether the OP has experienced this problem during the 18 months it has been installed. Is it a one-off issue due to weather conditions (ie wind direction and pressures can affect air intake through vents) or an installation issue.

Clairabella

How long since you last lit the log burner to dry out and warm up the chimney? Not a log burner but our open fire will never draw the first time we light it after the summer. It usually takes a couple of evenings burning before it becomes efficient at extracting smoke. Given all the wet weather we've had, could your chimney be just damp?