Supplied By www.heating spares.co Tel. 0161 620 6677
7
2.4
Domestic hot water mode
2.4.1
The heat exchanger in the D.H.W. circuit is
a stainless steel plate heat exchanger water
to water, and domestic water is heated by
converting the water in the central heating
circuit. The transference of heat is very high
because the two fl uids move in a counter
direction fl ow to each other.
2.4.2
Switch 1a Fig.50 in the winter position.
When a hot water tap is turned on a
diaphragm diverter valve excludes the central
heating circuit, the boiler automatically
modulates to maintain the domestic
hot water at a constant temperature.
Water temperature can be regulated using
the D.H.W. thermostat located on the front
control panel.
2.4.3
When domestic hot water is being drawn the
burner and pump perform as they do during
central heating except that the burner is
commanded by the D.H.W. thermostat.
2.4.4
When D.H.W. is no longer called for the boiler
automatically returns to the central heating
mode.
2.4.5
Switch 1a in the Fig.50 in summer position
The boiler functions like an automatic gas
hot water heater When D.H.W. is no longer
required the burner and fan immediately turn
off.
This also takes place when switch 1a is on
Winter if there is no demand for
heat to the central heating system or until
the room thermostat/time clock demands for
central heating circuit.
2.5 SAFETY
DEVICE
In both central heating and domestic hot
water mode safe operating is ensured by a
control board shuts off the main burner if the
fan stops or the fl ue or combustion air intake
duct is obstructed
2.5.1
An overheat cut off thermostat acts to
turn of the burner to resetable “lockout”
(Fig. 50) .
2.5.2
A safety valve is fi tted on the central heating
circuit set at 3 bar.
2.5.
3 A low water pressure switch set at 0.4 bar is
fi tted on heating circuit.
OVERALL DIMENSION
Fig.3
PRESSURE DROP ACROSS APPLIANCE
Fig.5
AVAILABLE PUMP HEAD
Fig.4
