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2.0 SYSTEM DESCRIPTION
F & E cistern
Thermal Store
P1
S4
PHE
S3
Electric heater
3kW x 2
CW
HW
IN
OUT
mCHP
return
mCHP
Standard Sealed heating
flow
expansion kit to be supplied
and fitted by installer.
Cold Rising Main
Approved Temporary
Filling Loop
mCHP
UNIT
Figure 2.2 Schematic diagram of a typical
mCHP BoilerMate A-Class 225 model installation
Note: With the 235 model, 2 F&E cisterns are provided
S1/S2
S6
P2
S5
P3
CH
CH
flow
rtn
1 bar
a r
b
1
Space heating circuit
PRV 3 Bar
The mCHP BoilerMate
A-CLASS
controls are shown in figure 2.5. All models
are fitted with a single channel clock for
programming heating 'on' times. All models
can be supplied without this clock for use
with a remote 2 channel programmer or
programmable room thermostat etc. These
should be supplied and specified by the
installer.
DOMESTIC HOT WATER
in the standby mode, the controller maintains
the plate heat exchanger between pre-set
temperature limits by cycling the plate heat
exchanger pump, P1. This cycling is controlled
by sensors S3 and S4.
When a hot water tap is opened, the controller
senses the flow of water by means of sensors
S3 and S4 (figure 2.2) and activates the plate
heat exchanger pump, P1. As long as the water
is flowing the controller regulates the pump
speed to maintain the domestic hot water
delivery temperature at 52
C (at 18 l/min).
o
When the loss of hot water flow is sensed, the
controller switches the pump, P1 off.
SPACE HEATING –
The central heating circuit is a separate sealed
system and will require the installer to buy and
fit a standard heating circuit expansion kit - see
figure 2.2 for the connection arrangements.
The space heating demand is controlled
by the heating programmer and the room
thermostat and its operation is independent
of the operation of the mCHP.
When both the space heating programmer and
the room thermostat are calling for heat, the
controller senses these demands and switches
on the central heating pump, P2. Therefore the
central heating water is heated indirectly by
means of a heat exchanger inside the store.
When either the programmer or the room
thermostat stop calling for heat, the controller
senses loss of space heating demand and
switches off the central heating pump, P2.
Page 8
appliance user
2.2.1
2.2.2
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