Cowls 

Here at Chimney Sweep North Devon we have the expertise to advise on the right type of cowl for your chimney be it live (in use) or redundant (not in use). 
 
We can also supply chimney cowls at competitive local rates. 

LIVE CHIMNEY COWLS 

Metal Hat Type Cowls - RECOMMENDED 

This picture is the type of cowl which is highly recommended by Chimney Sweep North Devon - for 3 reasons. 
 
1. The metal 'hat' keeps the rain out, This is especially important if the chimney is very straight. 
 
2. The mesh keeps out birds and debris. 
 
3. Perhaps most importantly, the height of the mesh allows the chimney sweep to get brushes right up and out of the pot without disturbing the cowl. This means the brush can be 'jiggled' to dislodge any build up of soot on the mesh thereby keeping the airflow to a maximum. The clamps on the OUTSIDE of the pot mean that when the chimney is swept, the brush will not push any 'legs' out from inside. 
 
(There is a Junior version of this cowl also - however, there is very little room for the brush to come up and we strongly suggest spending a few pounds more and purchasing the larger one.) 
 
 

Important! 

NOTE... Never EVER put a cowl for  
a redundant chimney on a live one. 
 
The back up of carbon monoxide can kill you - a lot of builders who do work on chimneys/stacks will use cowls which are completely unsuitable for the job. Some cowls even have it stamped on them that they should only be used on redundant chimneys and yet they are STILL being fitted to date. Be aware, stay safe! 
 

Mitre Type Cowls - To be AVOIDED!!! 

A lot of cowls have metal legs which just push into the top of the pot. These are unsuitable from the sweeps point of view and are easily dislodged or knocked off completely as the brush comes up from underneath. Not ideal for either the sweep or the client! 
 
These types of cowl are often bought because they are cheap. 
We do not recommend them for the reasons mentioned above AND... we have actually seen Jackdaws getting through the spokes!! No - we couldn't believe what we were seeing either!! 
 
It's cheap & cheerful but HIGHLY unsuitable - NOT recommended 

Anti-Downdraught Cowls - RECOMMENDED for chimneys with 'drawing' problems 

Anti downdraught cowls are for use where there are problems with the fire 'drawing' (getting enough air to suck the heat up the chimney thereby keeping the fire going). 
 
There are several reasons why a fire or stove does not draw properly you can find an extensive list on our Q & A page, however a few examples might be: 
 
The location of the property 
Are you low lying? 
Are there trees close by? 
Is your property in amongst other tall buildings? 
All these outside influences can have an effect 
Is it windy outside? Strong winds will quite often cause a change of direction and can create a temporary problem with the draw on the chimney. 
 
The stove itself 
Is it fitted correctly? An ill fitting stove will affect the draw on it. 
 
Is the correct cowl fitted? 
See the section below on Redundant chimneys. The wrong cowl could also have allowed birds to nest in the chimney. This WILL affect the draw!! 
 
Is it an open fire? 
An open fire often opens into a large chimney and the draw on this will be significantly reduced. In any case, at least 60% of heat from an open fire is lost up the chimney. 
 
Does it only happen in bad weather? 
Very cold weather will also affect the (initial) draw on a chimney. It is not unusual to get a blow back of smoke from both an open fire or a stove when lighting on a very cold day. It takes time for the chimney to heat up and warm the thermals which will draw the heat upwards. 
 
To help avoid a roomful of smoke, start with a small fire and allow the chimney to warm up slowly. Banking the fire up to begin with will almost certainly guarantee smoke!! Even if the fire was lit the day before, the chimney could well have cooled down dramatically overnight. 
 
Finally - and most importantly - has your chimney been swept? 
If it has - has it been swept properly? An unswept or badly swept chimney will undoubtedly cause you problems. 
 
Soot and creosote can build up inside the chimney. As it reaches the top of the chimney, it cools and this is where potential problems could be created. Any blockages are nearly always due to the build up of this residue and the only sure way to remove it is traditionally, with brushes. 
 
A long unswept chimney however, could have a build up of creosote (from wood) which has set like rock and cannot be removed by sweeping alone. 
 
Burning a chimney cleaning log can help flake this so that when it is swept, the chimney sweep can remove most of it with brushes. 
 

What sort of cowls can help? 

 
Aspirator Cowl - not to be used with an oil stove or boiler. The increased airflow could potentially damage the stove. 
 
Stainless steel cowl suitable for use with stainless steel flue system 

REDUNDANT CHIMNEY COWLS 

If you have a chimney in your Devon property which you do not wish to use, ideally it should have a cowl suitable for that purpose. If a chimney is left open to the elements then rain, birds and debris can cause a major problem. 
 
Rain can work its way down the chimney and bring old soot with it which can end up in your room if there is an open fire or it can run down the outside of a stove if fitted and cause it to rust which can make the stove look very unsightly along with thick black tar which it has collected on the way down and which will stain your fireplace. 
 
It is also a potential problem as it can eventually lead to holes forming in your wood/multi fuel stove - dangerous due to heat and, more importantly, fumes escaping into the room. It is also very expensive to put right... it is much more expensive to have to buy a new stove than it is to have a cowl fitted and your chimney swept regularly!! 
 
Birds can cause a problem when they nest in redundant chimneys. Many people have spent large sums of money on rendering and the stripping of walls to find a 'leak' which may only have been caused by rain 'leaching' through the sticks of a birds nest and into the chimney breast. 
 
This quite often happens in bedrooms where the chimneys are more often than not sealed up at the fireplace but which do not have a suitable anti bird cowl fitted. 
NONE OF THESE COWLS ARE SUITABLE FOR LIVE CHIMNEYS 
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