3
heat to the boiler. The burner can be set to the output
requirements as detailed in Tables 2 to 6.
Heatslave Tank
The Heatslave tank is a heatbank containing 46 litres (10
gallons) of primary hot water. The tank temperature is
controlled by the Domestic Hot water Control Thermostat and is
variable between 55°C and 80°C.
Domestic Hot Water Heat Exchanger
A Water to Water heat exchanger is located on top of the
Heatslave tank. Primary water is pumped from the Heatslave tank
to the heat exchanger whenever there is a flow of domestic water
through a hot water tap. The domestic water thereby extracts the
heat from the heatbank giving mains pressure domestic hot
water. The domestic hot water temperature can be increased by
reducing the water flow rate at the tap and/or adjusting the
Domestic Hot Water Control Thermostat to a higher setting.
Diverter Valve
A motorised diverter valve is located on the pump outlet. The
valve is normally closed to the primary circuit and is powered
open when there is a demand for central heating at a room
thermostat or a demand for heat via the Central Heating Control
Thermostat.
Pump
An integral circulating pump is incorporated within the
appliance casing. This serves the functions of both the central
heating circuit and the Heatslave tank. The pump is factory set
to Setting 3. This should not be adjusted, since this would impair
the domestic hot water performance.
Flow Switch
The domestic mains water inlet is connected to a flow switch
which detects when a domestic hot water tap has been opened.
This activates the burner and pump when the Domestic Hot
Water mode or the Central Heating and Domestic Hot Water
mode is selected. If the Facia mounted operating switch or
programmer (if fitted) is set to OFF or set to Heating On only,
then only the pump will be activated.
Pump Overrun
A pump overrun facility has been incorporated into the control
board which allows excess heat to be dissipated to the hot
water circuit when there is a demand for central heating via the
user operating switch (or programmer where fitted) or to the
Heatslave tank. This prevents the possibility of the boiler
overheating.
Expansion Vessel
A 12 litre expansion vessel is included within the appliance
cabinet.
Manual Reset Overheat Thermostat. See Figs. 3, 4, 5 and 6.
An overheat thermostat is located on the underside of the
electrical panel and is accessible by removing the cabinet front
panel. If a boiler overheat condition arises, the burner will
remain inoperative until the thermostat button is reset.
2.8 OPERATION
The appliance is supplied with a facia mounted operating switch
to allow the selection of hot water in the upper position or
central heating and hot water in the lower position.
Central Heating and Domestic Hot Water Mode
The appliance will supply heat to the central heating system as
required. The water supplied to the central heating circuit can be
set to the desired temperature by adjusting the Central Heating
Control thermostat.
The Heatslave tank will maintain the temperature set on the
Domestic Hot Water Control Thermostat. Demand by the
Domestic Hot Water Control Thermostat or a demand for hot
water at a tap or shower will override the central heating
requirement for the period of the demand. This will generally
have no significant effect on the average room temperature.
When the dwelling and boiler are to be heated from cold,
heating can be achieved more rapidly by turning the Domestic
Hot Water Control Thermostat fully anti-clockwise for the
duration of the warm up period. This will prevent the Heatslave
tank taking priority for the tank warm up period of
approximately 20 minutes.
Domestic Hot Water Mode
The Heatslave tank will maintain the temperature set on the
Domestic Hot Water Control Thermostat.
Central Heating Mode
This mode only applies where a two channel programmer has
been fitted to the system
The appliance will operate as a conventional oil fired boiler. The
water supplied to the central heating circuit can be set to the
desired temperature by adjusting the Central Heating Control
Thermostat.
A demand for domestic hot water at a tap or shower will
override the central heating requirement for the period of
domestic hot water demand. This will allow any residual heat in
the Heatslave tank to be utilised for domestic hot water
purposes.
NOTE: If the Heatslave tank is cold, then no domestic hot water
will be obtained from the system.
Off mode
The central heating system will remain off unless there is a
demand via the frost thermostat (when fitted), whereby the frost
thermostat will activate the pump and burner until the demand
is satisfied.
The burner will remain inoperative in all other circumstances.
If a demand for domestic hot water is made at a tap or shower,
primary water will be pumped from the Heatslave tank through
the domestic hot water heat exchanger. This will provide a
limited output of domestic hot water depending on the amount
of heat stored in the Heatslave tank.
This function will be found useful during periods where it would
be considered undesirable or uneconomical to keep the
Heatslave tank constantly hot, but where there may be a
demand for small quantities of domestic water for hand
washing etc. This would include overnight periods and any
periods of very low domestic hot water demand (eg during the
summer months). In these circumstances the Heatslave tank
can be charged up to maximum temperature once or twice a
day as required using the programmer in the Domestic Hot
Water mode and with the Domestic Hot Water Control
Thermostat set to maximum.
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