PLUMBING
REGULATIONS
The plumbing must be in accordance with all
relevant regulations and practices. It must include a
gravity circuit with expansion pipe, open to the
atmosphere. The central heating will normally be
pump-driven as with other types of boilers.
GRAVITY CIRCUIT
The gravity circuit consists of the domestic hot water
tank of 135 litres indirect cylinder, fixed in an upright
position, recommended for hot water storage and it
should be connected to the boiler by 28mm diame-
ter flow and return piping. The pipes should not
exceed 7.8 meters (25ft) in length and cylinder and
pipework should be fully lagged. The shorter the run
of pipe work the more effective the water
heating.There must be no gate valves on this circuit
and it must have an expansion pipe exhausting to
atmosphere. Cylinder and pipe work should be
lagged to minimise heat loss.
This diagram illustrates the basic principal of water
heating systems and must not be regarded as a
working drawing. See Fig.17.
Fig.17
INJECTOR TEE
Where the gravity and central heating circuits join
together to return to the stove we recommend the
use of an injector tee connection, situated as close
to the unit as possible. This type of tee encourages
a stable flow of hot water through both circuits and
helps to prevent priority being given to the stronger
flow, which is most commonly the pumped central
heating circuit. This way, there will be no shortage
of hot water to the taps when the heating is on.
WATER CIRCUIT TEMPERATURE
The return water temperature should be maintained
at not less than 40°C so as to avoid condensation on
the boiler and return piping. Fitting a pipe thermo-
stat to the flow pipe of the gravity circuit and wiring it
into the pump control will ensure rapid circulation of
the hot water.
In some circumstances it may be possible to over-
heat the appliance and the water inside will boil.
This will be evident by the sound of a knocking noise
coming from the appliance and pipes around the
house. If this occurs close off all air controls and
manually start the central heating pump if fitted.
One radiator on the heating circuit should be uncon-
trolled to act as a heat leak in the event that the
appliance overheats and has nowhere to discharge
a build up of hot water should the heating circuit be
satisfied. Be aware that steam and boiling water will
be expended from any open vent from the heating
system probably in the roof space at the expansion
tank.
In the unlikely event that the appliance is not oper-
ating in freezing conditions the water must be
drained from the boiler to prevent frost damage.
Injector Tee
Pump
STEP 4 - FIT CONTROL KNOB & INSERT
SPLIT PIN
D
10
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