A Quick Guide to Chimneys
If you want a solid fuel,gas or OIL fired Rayburn or Aga you will need a chimney
These can be originally built in the house or a prefabricated one can be added. There are MANY regulations so “just sticking up a pipe” will NOT do!
If your house was built before 1960 the chimney will probably NOT be lined – it MUST be to burn oil or gas , and its strongly recommended for solid fuel as well.
A good chimney is TALL – ridge height plus 3ft or more
it isn’t covered by overhanging trees or higher buildings
It can be lined with a clay pot liner or more cheaply with a flexible stainless steel liner that is dropped down from the top and connected via a vitreous flue pipe to your appliance. Concrete lining systems are also available .A builder (usually easier with a mate ) can do this in a day – providing there is no blockage on the way ! PLEASE get the flue swept before they arrive – not only does it save you mess but it makes fitting the liner easier (and possibly cheaper!)
NEW LEGISLATION – as from APRIL 2004 its necessary to have your chimney lined by an “approved contractor” to avoid having to get building regs relaxation. As the manufacturers haven’t even got around to sorting out a list of these , I doubt if your builder EVEN KNOWS about it! In my opinion its just more red tape that will put up the cost of the job ( but what do I know ?) So when you have unbent your bananas, have an EU approved house and use EU approved old Rayburns and Agas please make sure you have a chimney liner installed by someone with the correct piece of paper ( that they no doubt have paid a big fee for!)
I can’t tell you what it will cost but gas liner is the cheapest – solid fuel MUCH more expensive.
These can be of block work , rendered & built into the house or sectional that clip together & run up the outside or inside of the house.
They are a BUILDING ALTERATION so require permission to erect – both planning and building regs. In some areas these are “rubber stamps ” but if your home is LISTED it can be difficult to obtain permission. An Aga requires a 5″ internal diameter flue – a central heating Rayburn 6″ . Add 2 ” of insulation and then the second skin holds it all together. The chimney should be a TALL AS THE HOUSE to work properly. In the Cotswolds one of my clients wanted a natural stone chimney correctly added to natural stone barn conversion – but was only allowed to put up a stainless steel one (?)
We can now offer a FANNED FLUE on our oil burners – a box with electric fan that sucks out the gases- see photo
Problem Chimneys – Some causes
Insufficient height- not the highest point on the building. Not swept properly – fumes can KILL. Un-insulated single skin flue pipe – causes condensation & rots out your cooker ( especially if let out for the summer ) Incorrect cowl – a gas cowl on an oil appliance will cause problems. A shared flue – not a good idea . Too high a chimney – too much “suck” gives low heat in the cooker – especially Agas .
NEW REGS again ! Gas Aga and Rayburns (inc conversions ) now have a CHIMNEY OVER HEAT thermostat which cuts OFF the gas if the flue box gets TOO HOT. It’s usually a small insert under the thermocouple – between it and the valve. So when installing a GAS cooker you MUST NOT use the standard GAS LOUVERED COWL . Instead fit an OH or Odette anti downdraft type which gives a free flow of exhaust gases under all wind conditions.
Balanced Flue gas cookers
ONLY available on some GAS cookers that were designed for that flue- conversion from conventional flue isn’t possible economically.
What happens is you have two tubes out of the back of the cooker – and they MUST be straight outside less than 18″ long . One carries the burnt gases out and the other brings new air in .
This system can be found on Rayburn Nouvelles (now obsolete so DO NOT BUY) and also some Agas .
There are sensible rules on where such a cooker can be located. Obviously under opening windows is out, plus several other places. E mail me if you want this type of cooker
Don’t despair – consult a flue specialist . If you want some E mail advice you can link to www.chimneyworks.co.uk
Chimneys can be really expensive ( cheapest gas, solid fuel most expensive ) so NEVER buy a cooker until you know what involved – get your QUOTE first!