11
Indep Combi -
Installation and Servicing
gENERaL
general
1. The installation must comply with all relevant national and local
regulations.
2.
The installation should be designed to work with flow temperatures
of up to 86
o
C.
3. All components of the system must be suitable for a working pressure
of 3 bar and temperature of 110
o
C. Extra care should be taken in
making all connections so that the risk of leakage is minimised.
The following components are incorporated within the appliance:
a. Circulating pump.
b. Safety valve, with a non-adjustable preset lift pressure of 3 bar.
c. Pressure gauge, covering a range of 0 to 4 bar.
d. An 8-litre expansion vessel, with an initial charge pressure of 0.75 bar.
4. ‘Make-up’ Water. Provision must be made for replacing water loss
from the system, either :
a.
From a manually filled ‘make-up’ vessel with a readily visible
water level. The vessel should be mounted at least 150mm
above the highest point of the system and be connected through
a non-return valve to the system, fitted at least 150mm below
the ‘make-up’ vessel on the return side of the radiators. or
b.
Where access to a ‘make-up’ vessel would be difficult, by pre-
pressurisation of the system.
The maximum cold water capacity of the system should
not exceed 143 litres, if not pressurized. However, if the
system is to be pressurized, the efficiency of the expansion
vessel will be reduced and a larger vessel (or smaller system
volume) may be necessary. If the capacity of the vessel is
not considered sufficient for this, or for any other reason,
an additional vessel MUST be installed on the return to the
boiler.
Guidance on vessel sizing is given in Frame 2.
5. Filling -
The system may be filled by the following method:
Where the mains pressure is excessive a pressure reducing valve
must be used to facilitate filling.
a.
Thoroughly flush out the whole system with cold water.
b.
Fill and vent the system until the pressure gauge registers
1bar and examine for leaks.
c.
Check the operation of the safety valve by raising the water
pressure until the valve lifts. This should occur within 0.3bar
of the preset lift pressure.
d. Release water from the system until the
minimum system design pressure is reached;
1.0 bar if the system is to be pre-pressurised.
Notes
a.
The method of filling, refilling, topping up or flushing sealed primary
hot water circuits from the mains via a temporary hose connection is
only allowed if acceptable to the local water authority.
b.
Antifreeze fluid, corrosion and scale inhibitor fluids suitable for use
with boilers having aluminium heat exchangers may be used in the
central heating system.
2
sysTEM REqUIREMENTs - Central heating
Water Flow Rate and pressure Loss
Max CH Output
kW
24.2
(Btu/h) (82,600)
Water flow rate
l/min
17.3
(gal/min) (3.8)
Temperature Differential
o
C 20
(
o
F) (36)
Head available for
m.w.g.
3.4
system
(ft.w.g.) (11.1)
safety valve setting bar
3.0
Vessel charge pressure
bar
0.5 to 0.75
system pre-charge pressure bar
None
1.0
system volume
Expansion vessel
(litres)
volume (litres)
25
1.6 1.8
50
3.1 3.7
75
4.7 5.5
100
6.3 7.4
125
7.8 9.2
150
9.4 11.0
175
10.9 12.9
190
11.9 14.0
200
12.5 14.7
250
15.6 18.4
300
18.8 22.1
For other system volumes
multiply by the factor across
0.063 0.074
DOMEsTIC hOT Wa TER
1. The domestic hot water service must be in accordance with BS
5546 and BS 6700.
2. Refer to Table 1 for minimum and maximum working pressures.
In areas of low mains water pressures the domestic hot water
regulator may be removed from the DHW flow turbine cartridge.
Refer to Frame 69. The boiler will require the flow rate to be set
to obtain a temperature rise of 35
o
C at the tap furthest from the
boiler.
3. The boilers are suitable for connection to most types of washing
machine and dishwasher appliances.
4. When connecting to suitable showers, 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 water supplies to the shower are of equal
pressure.
5. hard Water areas
Where the water hardness exceeds 200mg/litre (200ppm), it is
recommended that a proprietary scale reducing device is fitted
into the boiler cold supply within the requirements of the local
water company.
IMpORTaNT. Provision MUST be made to accomodate the expan -
sion of DHW contained within the appliance. If the DHW inlet
contains a back flow prevention device or non-return valve, e.g. a
water meter, then a mini expansion vessel should be fitted between
the device and the boiler in the cold inlet pipe.
Cold water, rising main & pipework in exposed areas need to be
suitably lagged to prevent freezing.
DHW Expansion Vessel Kit available from Ideal.
CH Return
Hose unions
Mains
water supply
Temporary hose
(disconnect after filling)
Additional
stop valve
Double check valve
assembly
(
note direction of flow
)
