The recommended heating surface area is based on an
average heat emission of 0.5 kW/m
2
(160 Btu/h/ft
2
).
These figures are maxima and must not be exceeded.
A margin (about 10% or 1.4m
2
- 15ft
2
) is recommended.
The Much Wenlock Stove with Boiler is intended to
provide space heating and the heating of domestic hot
water and radiators has been approved by the HETAS LTD
Appliance Approval Scheme. The appliance and burning
rate are controlled by the manual adjustment setting of
the ashpit door spinwheel only.
1. A 140 litre capacity indirect hot water storage cylinder
of the double feed type, complying with BS 1566 Part
1: DF TYPE 8 should be lagged and fixed vertically as
near as possible to the stove.
The 28mm minimum diameter primary flow and return
pipes must not exceed 10m in length and pipes longer
than 5m must be lagged. Ensure that the flow pipe
rises continuously from the stove boiler to the cylinder
to ensure good gravity circulation. In combined
systems, the water draw-off pipes to the taps must be
dead-leg connections from the vent/expansion pipe.
2. One boiler flow connection (preferably that to the
cylinder), must have an open vent. The connection to
the boiler must be such that air cannot be trapped in
the boiler. Any pipe size reduction must be made on
the vertical pipe of the vented flow pipe.
The heating flow and return pipes may be 22mm and
should preferably be connected to opposite tappings
to each other on each side of the boiler.
3. All installations must be fitted with a drain tap at the
lowest point of the system.
4. It is recommended that a gravity heat leak radiator 0.9
- 1.4m
2
(10-15ft
2
) heating surface be included, or a
reverse acting cylinder thermostat to activate the
pump in the event of overheating.
5. Long reach male fittings will be required to make
pipework connection into the boiler.
For correct operation of the appliance, the height of the
chimney from its base should not be less than 5.5m and
terminate above the roof in accordance with current
Building Regulations Section J/1/2/3 and requirements as
outlined in BS 6461 Part 1 and BS 7566 Parts 1 to 4
should be observed.
The structural flue through the chimney should not be
less than 175mm diameter. Pargeted lined flues, 230mm
x 230mm must be in sound condition, and any internal
offsets should not be less than 60
˚
to the horizontal.
Check that the flue exit is not obstructed or reduced in
size.
IMPORTANT:
FAILURE TO OBSERVE THE
RECOMMENDED MINIMUM SIZE OR METHODS OF
FLUE CONNECTION MAY LEAD TO EMISSION INTO
THE ROOM AND REDUCED BURNING RATES.
Existing Chimney
The internal and external condition of the chimney should
be checked
before
the appliance is installed and
rectification made where necessary to prevent air leakage
or porosity.
The flue through the chimney should be formed with
175mm diameter minimum moisture and acid resistant
liners to BS 1181 or precast linings as specified in the
current Building Regulations and requirement in BS 6461
Part 1 and BS 7566 Parts 1 to 4 should be observed.
When repairing existing chimneys, it is recommended
that the Building Inspector be consulted before
commencement of work with particular attention to the
chimney height and its termination.
NOTE: THE CHIMNEY MUST BE SWEPT BEFORE
INSTALLATION.
Where the chimney is believed to have served an open
fire installation it is possible that the higher flue gas
temperature from a closed appliance may loosen
deposits that were previously firmly adhered, with the
consequent risk of flue blockage. It is therefore
recommended that the chimney be swept a second time
after one month of regular use.
New Chimney
The flue should not be less than 175mm diameter and its
soundness confirmed by smoke testing or consulting
HETAS LTD who will give advice on the test method.
Ensure the chimney liners are free of any internal
projections such as building jointing composition before
the appliance is installed.
Factory-made Insulated Chimneys
It is recommended that the internal face of the chimney,
be refractory lined and otherwise comply with BS 4543.
The recommended minimum diameter is 150mm and
chimney manufacturers should be consulted for further
advice.
HOT WATER SYSTEM
THE CHIMNEY
PERFORMANCE
2