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 Install an automatic chimney (firebox) draught stabiliser


Firebox and stoves needs correct and constant draught to run well. If depression in the conduct is too high then fire regulation will be quite impossible resulting in heavy wood consumption and low comfort. Moreover if too high it will induce an uncontrolled reaction more the draught will be high, more the wood combustion will increase, inducing by the same more and more draught and so on...

Draught is determined by several factors as firebox type and mainly chimney conduct length and design. It can hardly been modified after built.

One easy to lower draught is to install and automatic stabiliser. This device is in fact very simple, a flap opens under depression and allows a certain amount of fresh air entering in the conduct. The opening regulation is made by use on a counter weight (more depression will be important more flap will open).
Fresh air has a twin effect lowering draught by the additional air amount but also lowering the conduct temperature and so the tendency of fumes to go upwards.

Several models are available on the market from simple model with a weighted flap and other more evolved with screw adjustable counter weight. For weighted flap model as presented on the picture the depression adjustment is made by turning the flap (more flap axle is vertical, more it will open quickly).

Best is to install this device during firebox installation, but if not you will still be able to add it after. For this you will have to replace the first tube of the conduct by a T section. Regulator as to be installed on a horizontal tube section. It must also be placed at a certain distance (at least 30 cm) from the main tube in order to avoid to be sooted by smokes (otherwise it would need often cleaning to work well).
Mechanism is simply attached on the pipe by the mean of two spring hooks that goes in tiny holes.
For finishing you can cut old conduct to correct length or install a new tube. Take care to attachment and sealing to avoid fumes to escape from tubing.

After installation you will need to test and adjust your draught stabiliser. Preferred method is to check with a vacuum gauge (this has to be done with a fire at running temperature) but if you don't have one you can adjust it step by step up to obtention of a good result. Caution : when adjusting do not open manually or remove the regulator from the pipe when there is a fire this could cause flashback. Adjust it carefully or proceed by steps when fire is extinguished.

If well adjusted you will notice improvement for fire adjustment and a lowered wood consumption. But remind that for optimal result always use dry wood and do not overload your fire place, this will not increase burning time.
This device can also be installed on fuel or gas boilers.