£200.00 Ex VAT (£240.00 Inc VAT)
1 in stock
How Does it Work?
The Aderyn cowl is a directional cowl that provides complete dynamic protection to the chimney flue from wind-driven rain and downdraughts. The body of the Aderyn cowl provides a protective shroud rather like a large umbrella, and the pivot point is positioned behind the head which acts as a wind vane that ensures the cowl always faces away from the wind, fully protecting and shielding the chimney pot.
Wind-driven rain normally enters any standard cowl, and this can result in water being funnelled directly down into a stove in the case where a chimney liner is installed, causing rusting or damage to the stove lining. The Aderyn cowl prevents any wind-driven rain entering the chimney, whether in heavy vertical rain or the near horizontal gale-driven showers and squalls that are a common feature of our weather in the UK.
The aerodynamic design and quality of the twin sealed bearings ensures that the Aderyn cowl responds instantly to any breeze, protecting the chimney at all times.
Increased Chimney Draw
To work properly a chimney must have draw, both to clear the products of combustion and to provide fresh combustion air to the fire. This is equally true whether the chimney is serving a traditional open fire, a fire-box or a wood or a multifuel or woodburning stove.
Because the Aderyn cowl faces away from any wind, a low pressure zone is created on the lee side just above the chimney pot. The result is better chimney function, which reduces the chances of tar and creosote formation that can occur in sluggish flues.
The wind blowing across the top of any chimney is rarely a smooth, steady, laminar flow. The proximity of another building, trees, adjacent roof pitches or other feature will cause turbulence which can frequently cause problems. Obstructions often produce ‘rotors’ that result in reverse flow in the chimney, or downdraught. Everyone has experienced reverse flow, which is commonly only temporary, but causes the fire or stove to puff clouds of smoke into the room. No cowl can be guaranteed to cure all types of downdraught as the causes are so varied, but tests and observations have shown that the Aderyn cowl is one of the best at doing exactly that because unfavourable downward air flows are split by the cowl and directed over each side of the pot, and the low pressure zone just above the pot is pre-served, maintaining chimney function.
It is not often appreciated how important it is to keep rain out of a chimney and to keep the flue dry. Soot and tars are acid, which are harmless when dry, but the addition of moisture will allow the formation of strong sulphuric and nitric acids which attack the fabric of the chimney. This is the cause of the commonly-seen defect where the top few brick courses of the stack are falling apart, or where a stack is leaning due to acid-induced swelling of the mortar on one side.
The Aderyn cowl provides exceptional dynamic rain protection by shielding the chimney from both vertical rain in still conditions and wind-driven rain glancing in at any angle right down to the near-horizontal experienced in the worst storm-force winds.
Observations have shown that birds do not like the Aderyn cowl. For obvious reasons! In addition, the moving body prevents birds perching and discourages approaches for the purpose of nest-building.
The cast aluminium base is exceptionally free-flowing and offers very low impedance to flue gases. The open body of the cowl has a clearance area greater than the chimney pot cross-sectional area and likewise offers very low impedance to smoke and flue gases. An effect of standard Chinese-hat type cowls which is not often appreciated is the tendency for smoke to ‘bounce’ off the underside of the cap and travel downwards thereafter. To understand the effect, try holding a spoon the right way up under a running tap! In certain conditions, this is enough to send the smoke right down to the ground where it can become a nuisance. By contrast, the Aderyn Cowl simply deflects the smoke, which can continue to rise at all times.
Fits flue sizes 150mm to 260mm
From 150mm to 180mm you will need need a flue pipe adaptor. (Please contact us for futher information)