A draught stabiliser from Kutzner and Weber.
Models ZUK are without a positive pressure damper, and are used for reducing excess negative draught in the chimney system.
How a Draught Stabiliser Works
A draught stabiliser is a component that should be included in your flue system where there might be a possibility that the flue draught will surge more than is required by the appliance. They can be installed on multiple pressure jet boiler flue systems, fan assisted flues and flues for individual natural draught pressure jet gas, oil and wood pellet boilers.
Typically, all the appliances mentioned require a negative draught of approx. 10 Pascals when the full output is reached. This is sufficient draught, when designed to a correct diameter, to expel the emitted gases at a correct velocity that lessens the
chances of condensation.
When a flue is higher it can create too much draught. This can be typically on start up, when the appliance is on low fire and doesn't need so much draught, or when a smaller number of boilers are functioning than the flue might be designed for. At this
time the door on the stabiliser will be pulled into the flue and so the extra opening relieves the appliance of the excess draught. For this type of installation you require the ZUK model.
Pellet burners work slightly different. During the initial firing there is not enough draught to clear the relatively massive amount of combustion smoke that is released into the flue. For this type of appliance you should install the ZUK S model. This
model has a silicone seal around the door, thus allowing the positive pressure created by the initial smoke to be held within the flue until a negative draught is created. The draught stabiliser will then work to relieve any excess draught from the burner.
How to Install and Set Up a Draught Stabiliser
The draught stabiliser should be installed onto the the branch of a tee piece. The tee should be installed within the first 1 metre of the appliance, if possible, to get the best effect.
The door of the stabiliser has a weight system on it that can be increased as required. When commissioning the appliance the door should be weighted so that, during normal constant firing, it lies approx. 5 degrees from vertical into the flue. From this
position the door will close or open as the draught demands.
When a fan is used the draught stabiliser should be sited near the boiler but between it and the fan unit.
The stabiliser, through controlling the draught, makes sure that your appliances work more efficiently. A too stronger draught can pull the flame off the burner and so the appliance can use more fuel or shut down altogether.
Kutzner and Weber Draught Stabilser Brochure
Good value This 130mm unit seems well engineered, but would not comfortably fit my 125mm flue. I couldn't find a suitable adapter. What appears to be a centreing adjustment prevented its engagement fully. However, it can be fitted with a little metalwork. German only instructions not helpful.
Milais - Newport Pagnell