Multifuel stoves - strange phenomenon.

[RigidRaider]

We have identical Douvre 500 multi fuel stoves in the dining room and the lounge. Both rooms are the same size and both have the same doors and windows. Both have the same wall vent. Both have the same chimney, flue, pot and anti-downdraft cowl on the same gable of the house. Both were installed by the same experienced chimney sweep at the same time.

So they should burn the same, right?

They don't. The one in the lounge draws vigorously and never smells when not burning. The one in the dining room draws sluggishly, is difficult to light, smells when lit and when not lit a blast of cold air smelling of tar comes out of the bottom and airwash vents. We only light the dining room stove on special occasions and this holiday we have run it for several days and even when thoroughly warmed up it is still sluggish, so it's not as if there's a difference in flue temperatures.

How can they be so different? The lounge is on the west of the house and the dining room on the east. The ridge of the roof runs north-south. This week the wind has not been westerly at all. The tarry sooty smell in the dining room is very strong.

Does anybody know anything about the finer points of flue science and room air pressures, which could explain this difference?

 

[noseall]

It is true to say, that in some cases having multiple chimneys can be a problem. Having say two stacks encourages the air to move negatively through one and positively through t'uther, though this is usually cured with a closed door.

Strange.....

 

[ColJack]

if they have their outlets on the same gable of the house but are at different ends of it then one must assume that at least one of them isn't a straight shot from fire to chimney..
it's these bends etc that affect the airflow..

 

[RigidRaider]

Two separate chimneys, both have straight vertical flues. Both are dedicated to the downstairs fireplaces.

 

[Trazor]

Is your dining room more airtight than the lounge, if so would this hinder the fire from drawing enough air ?

 

[dave.m]

What condition are the rope seals around the doors and the ash pans flaps?
Are they similar in condition or is one letting air past and the other sealing airtight.

 

[RigidRaider]

The dining room stove is sluggish with the door open or closed. Both rooms have identical vents within five feet of the stoves. The installations are actually a perfect mirror image of each other in every single respect.

The rope seals are in good nick on both stoves and the doors are clamping shut firmly, leaving the seals well crushed and a corresponding pattern on all the sealing faces. The sluggish draw is evident even when lighting the stove with the door part open.

What I'm trying to get at is that with two indentical stoves operating in identical settings the only thing that can be different is the air pressure in the flues, which must somehow be affected by the air flow around the house or over the roof. I know this is a complex subject and was hoping someone could give me an insight into this.

 

[Nige F]

Indeed it could be a Pressure zone ...like one on a block of flats in a Seaside town I visited ( to work on ) No obvious or apparent reason why - but the gas flue fires were all condemned ( by CORGI @ the time ) and it was a result of a Pressure zone ..If or what equiptment was used ,I wasn`t privy to it.