1. A 140 litre (30 gallon) capacity indirect hot water
storage cylinder of the double heat type, complying
with BS 1566 Part 1: DF Type 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 no
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 connection from the
vent/expansion pipe.
2. One boiler 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.
If there is a possibility of boiling taking place a reverse
acting thermostat should be fitted to the cylinder or
primary flow pipe and electrically connected to the central
heating pump. This will switch on the pump to prevent
boiling.
Central heating pumps which are continually operative
will, in conjunction with prolonged burning under banked
conditions, create cool boiler surfaces within the firebox.
This, in turn will encourage boiler surface condensation
followed by surface oxidisation and reduced lifespan of
the boiler. To minimise this effect we strongly
recommend that a water pipe clamp-on thermostat be
fitted to the heating return pipe close to the stove. The
thermostat should be electrically connected to the pump
as indicated on the Typical Wiring Diagram in Fig. 1 and
the adjustable dial should be set at a temperature of 50
˚
C (122
˚
F). A fall in the return pipe water temperature
below 50
˚
C interrupts the power to the pump which will
then not operate until the temperature exceed 50
˚
C and
power is restored.
3. All installations must be fitted with a drain tap at the
lowest point of the system.
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 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 200mm diameter. Pargeted lined flues, 288mm
x 228mm must be in sound condition.
Where a bend is necessary in a flue, it should not make
an angle of more than 30
˚
with the vertical.
IMPORTANT: FAILURE TO OBSERVE THE
RECOMMENDED MINIMUM SIZES OR METHODS OF
FLUE CONNECTION MAY LEAD TO FUME EMISSION
INTO THE ROOM AND REDUCE 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
200mm diameter minimum moisture and acid resistant
liners to BS 1181 or precast linings as specified in the
Current Building Regulations. Requirements 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 the
commencement of work with particular attention in the
chimney height and its termination.
NOTE: THE CHIMNEY SHOULD BE SWEPT BEFORE
INSTALLATION.
New Chimney
The flue should not be less than 200mm diameter and its
soundness confirmed by smoke testing and contacting
HETAS LTD who give advice on the test method.
Ensure the chimneys 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
should be refractory lined and otherwise comply with BS
4543.
The recommended minimum diameter is 175mm and
chimney manufacturers should be consulted for further
advice.
THE CHIMNEY
HOT WATER SYSTEM
2
