Good stove design
What is better steel or cast iron?
Traditionally stoves were made from cast iron sections, bolted together
and sealed with fire rope. Plenty of stoves are still made this way
although increasingly many modern stoves are made from shaped steel
panels and then welded together. Both models have their advantages
and some stoves combine both techniques usually steel bodies and
cast doors.
Advantages of steel
Steel tends to be lighter and therefore heats up sooner.
Steel lends itself to more intricate shapes and designs.
Steel has less propensity to crack, cast iron is quite brittle
when hot. If the welds fail on a steel stove, the stove can usually
be repaired using nothing more elaborate than a garage welder.
Steel stoves tend to have a better air seal by virtue of they
fact they are metal boxes welded together rather than bolted and
fire rope sealed.
Advantages of cast iron
Iron holds its heat for longer acting like a radiator.
Iron does not warp with heat.
Iron better withstands the corrosive effects of the the flue gas.
As a foot note their are also a few ceramic and stoves of even
more esoteric construction. Many stoves combine several forms of
construction and a recent trend has been steel stoves clad in
soapstone. The soapstone heats up quickly and acts a heat diffuser,
as well as having longevity and a pleasing appearance.
What constitutes a well designed stove?
This is not an objective standard that can be applied each
appliance considered. It is better to think does the stove in question
fulfil my requirements. However that said there are a few general
criteria that can be applied.
Efficiency?
All stoves legally manufactured and sold in the UK and EU need to
meet at minimum efficiency of 65%. However most stoves achieve
efficiencies in the mid 70s and the British made
Burley Hollywell 9105 claims an 89.1% efficiency and is considered
the world's most efficient stove. It is available in Brighton & Hove
via Sean Wilson the
Brighton Chimney Sweep 01273 689414.
I consider a stove to be of 'high efficiency' if the manufacturer
can claim an 80% or greater test result. It is unusual of multi fuel
appliances to reach this figure although some like
Broseley's Serrano series
do.
Efficiency is measured by taking samples of the waste flue gas -
usually using a flue gas analyser the chemical composition of the gas
indicates how efficiently the fuel has been burned and its temperature
indicates how much of the heat generated has been captured and how
much is lost into the chimney. It is not normally practical to measure
directly the heat output.
Most stoves have different figures for different fuels. Sometimes
this stated on the CE plate or in the user instructions.
Multi-fuel or wood only?
Despite the popularity of multi-fuel stoves most people, most of
the time burn wood. Coal and smokeless mineral fuels are a minority
pastime. Many manufacturers sell additional kits to convert wood
stoves into multi-fuel appliances, but by doing so you usually
comprise the stove's efficiency. The most significant distinguishing
feature of a multi-fuel stove is it's grate. The Grate is usually more
robust (to deal with the higher temperatures generated by mineral
fuels) and has more ventilation (mineral fuels burn better with air
under them).
If you are intending to burn coal of mineral fuels a 'Jiggler' is a
nice feature. It is a means or moving the grate so as to allow some
ash to fall through into the ash tray and allowing more air to move
past the fuel. Firefox stoves have particularly neat and robust
jigglers.
Size of firebox and opening?
It sounds too obvious to mention but the bigger the firebox and the
larger the door the larger the logs that can be easily burnt. This is
a consideration when you are ordering in fuel. Most suppliers will
supply logs of an appropriate size if asked. My view is large door
equals better stove but this is not universally shared.
Top or rear flue?
Top outlet stoves tend to offer higher efficiencies. Many stoves
have a facility for changing from one outlet to the other and current
building regulations allow rear outlets to connect to a right angle
providing it is in direct proximity to the stove. If efficiency is not
an issue this is usually a matter of aesthetics.
Appearance?
This usually comes down to 'traditional' or 'contemporary' although
some manufacturers do make appliances that are at home in both
situations.
A few manufacturers finish their stoves in coloured paints and
enamels. Carron make stoves finished in a high gloss white and red
enamel that is striking and surprisingly easy to keep clean. However
some of these finish 'craze' over time and whilst this is not a
problem to some it is to be expected. Of course the standard black or
mid grey is probably the easiest finish to keep looking as new, and
touch in when marked.
I also offer the Grey Metal
Cube in a custom finish.
Price?
You do get what you pay for, but its not always quite a straight
forward as you might think. Your money can buy significantly more or
less in different countries.
The Chinese are manufacturing some of the cheapest stoves available
in the UK and EU. Some are appalling in quality, badly cast, badly
finished, fraudulently CE marked. Some such as
Firefox, Capital, Tiger
and Sunrain are simply the best value for money stoves on the market
and more than a match for most of their competitors.
Since the accession to the EU of the former 'eastern bloc'
countries, many appliances from these states have found quite a market
in the UK. Most of these states have had a good history of metal
working and use of solid fuel and in states such as Poland use of coal
is as much part of the national character as it was in Wales.
France and Spain have a long history with solid fuel appliances and
as such their industries tend to produce a large range of appliances
from budget to high end. I like (and sell)
Invicta appliances from
France and Panadero stoves from Spain, they both offer quality at
excellent prices.
British made appliances tend to be expensive, not quite in the
Scandinavian price bracket but expensive compared to their
competitors. They also tend to be well made and well supported for
spare parts. Aga, Aarrow Villager, Clearview Chesneys and Stovax all
make quality stoves as do some new comers such as
Broseley and
Burley.
Less than £400 will usually buy an excellent Chinese made stove,
similarly true for most eastern European manufactured items. Expect to
pay more for French and Spanish stoves and maybe double for British
made appliances.
Particular design features?
The baffle or throat plate is the part of the stove that takes much
of the heat and therefore wear in the stove. In general terms cast
iron is better than pressed steel, however if steel is used one piece
is better than a welded as it decreases the chances or warping. The
thicker the steel the better.
If the stove has any adjusters or bolts inside the firebox the
bigger and chunkier the better. Fire causes screws and bolts to
corrode and should any adjustments need to be made over time the
bigger the adjusters the less the corrosion is likely to affect their
function.
Fire bricks add longevity to stoves by taking the worst of the heat
and extending the life of the stove body. They periodically need to be
repaired when the crack and crumble and are a means by which stove
manufacturers get high efficiency levels out of their appliances.
Door adjustors seem unnecessary until required, not many stoves
have them but if required they are indispensable.
Other features?
Feet that are adjustable to facilitate the levelling of the stove
are a useful feature from my perspective as an installer although most
stoves can be levelled without adjustable feet.
Self closing doors seem to be in vogue at present, however they
annoy me and most chimney sweeps.
Some stoves such a Panadero incorporate ovens and plate warmers.
Log stands are a useful feature some stoves incorporate them in the
design others allow sympathetically designed log stands to be bolted
onto the body of the stove.
Convector stoves allow the heat of the stove to be felt in the room
sooner than by relying on radiation and conduction. Most convector
stoves are steel although I have encountered a few cast iron
convectors.
DEFRA approval?
My view is that DEFRA approval is double edged sword. If you are in
smoke control area (SCA), there is little alternative if you wish to
comply with the legislation. However part of the specification of
DEFRA approved stoves is that the air control vents cannot be fully
closed. This usually means DEFRA approved appliances use more fuel and
often have lower efficiencies than non DEFRA approved stoves.
This can also cause some difficulties if your chimney or home are
prone to downdrafts.
HETAS approval?
HETAS (Heating Equipment Testing and Approval Scheme) is the
official body recognised by Government for testing and approving of
solid fuel appliances. If an appliance is HETAS approved it can be
assumed the appliance complies with the latest legislation for
efficiency and safety.
If a given appliance is not HETAS approved (and many are not) it
does not mean the appliance does not comply with legislation merely
that the manufacturer has not or not yet submitted the appliance to
HETAS.
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