GENERAL
Mini
Installation & Servicing
11
For expansion volumes see Table 5.
Table 6 Mini C32
System charge pressure
(bar)
0.5
0.7
1.0
Safety valve setting
3.0
Vessel pre---charge pressure
(bar)
0.7
System volume (litres)
Volume of expansion vessel
in addition to 7 litre unit
fitted to boiler
75
---
---
---
100
---
---
0.4
125
0.8
1.6
2.3
150
2.5
3.4
4.1
175
4.0
5.1
6.0
200
5.6
6.8
7.8
225
7.2
8.6
9.7
250
8.8
10.3
11.5
275
10.3
12.0
13.4
300
11.9
13.7
15.2
Multiply this factor by
system volume and deduct
7 litres to obtain size of
additional vessel for other
system volumes.
0.063
0.069
0.074
For the system water expansion to be contained by the
7
litre
expansion vessel fitted to the following model:
Mini C32
the cold system volume must not exceed:
111 litres when pressurised to 0.5 bar (cold)
101 litres when pressurised to 0.7 bar (cold)
95 litres when pressurised to 1.0 bar (cold)
If the pressure exceeds 2.65 bar when the boiler is up to
temperature with all radiators in use then an additional
expansion vessel MUST be installed on the return pipework.
For expansion volumes see Table 6.
Guidance on vessel sizing is given in BS 7074:1 and BS 5449
For IE refer to the current edition of I.S. 813.
6 Hydraulic Loss
Remaining pump capacity
Flow rate l/hour
m H2O
0
1
2
3
4
5
6
0
200
400
600
800
1000
1200
1400
7 Draining the system
Draining taps MUST be located in accessible positions to
permit the draining of the whole central heating system,
including the central heating side of the boiler. The taps
should be at least 1/2” BSP nominal size and be in
accordance with BS 2879.
5
BOILER CONTROL INTERLOCKS
Thermostatic radiator valves.
Ideal Stelrad Group.
support the recommendations made
by leading manufacturers of domestic heating controls that
heating systems utilising full thermostatic radiator valve
control of temperature in individual rooms should also be
fitted with a room thermostat controlling the temperature in a
space served by radiators not fitted with such a valve as
stated in BS5449. Such an arrangement will provide for a
more efficient control of the environment and will also avoid
the continuous running of the circulation pump during
programmed heating ON periods, saving electrical energy.
It is therefore strongly recommended that, when thermostatic
radiator valves are used, the space heating temperature
control over a living/dining area or a hallway, having a heat
requirement of at least 10% of the boiler output, is achieved
using a room thermostat whilst other rooms are individually
controlled by TRV as stated in BS5449.
For further information refer to “Good Practise Guide 143” a
publication of the energy efficiency office, available from the
building research establishment Garston Watford WD2 7JR
tel: +44 (0) 1923 664258
The boiler is fitted with an automatic internal bypass. No
further system bypass is required.
Typical installation
D
A
TRV
B
Room
T/stat
Balancing valve
TRV
TRV
6
DOMESTIC HOT WATER
REQUIREMENTS
1 The domestic hot water service must be in accordance
with BS 5546 and BS 6700.
2 For the minimum and maximum working pressures of the
Mini C24
,
Mini C28
and
Mini C32
domestic hot water
circuit refer to Table 1, page 4.
3 The cold water supply pipe should be flushed before
fitting the boiler.
4 The boilers are suitable for connection to most types of
washing machine and dishwashing appliances.
5 When connecting to suitable showers, i.e. those designed
for modulating domestic hot water, ensure that:
a. The cold inlet to the boiler is fitted with an approved
anti---vacuum or syphon non---return valve.
b. Hot and cold supplies are of equal pressure.
6 Hard water areas
In areas where the water is ’hard’ it is recommended that
a proprietary scale---reducing device is fitted into the boiler
cold supply, within the requirements of the local water
company.
