9
combination boiler -
Installation and Servicing
GENERAL
4
SYSTEM REQUIREMENTS - CH (continued) and HOT WATER
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 82
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.
A 5-litre expansion vessel for
europa 24
and a 8-litre
expansion vessel for
europa 28
, with an initial charge
pressure of 1 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 150 mm above the highest point of the system and
be connected through a non-return valve to the system,
fitted at least 150 mm 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 67 litres for
europa 24
and 108
litres for
europa 28
, if not pressurized. However, with
the system 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 3.
5. Filling.
The system may be filled as follows:
Through a temporary hose connection from a 'draw-off'
tap, supplied from a service pipe under mains
pressure. Where the mains pressure is excessive, a
pressure reducing valve must be used to facilitate
filling.
i.
Thoroughly flush out the whole system with
cold water.
ii.
Fill and vent the system until the pressure gauge
registers 1.5 bar, and examine for leaks.
iii.
Check the operation of the safety valve by raising the
water pressure until the valve lifts.
This should occur within 0.3 bar of the preset lift
pressure.
iv.
Release water from the system until the minimum
system design pressure is reached;
1.0 bar if the system is to be pre-pressurised.
When installing the filling connection provided with the
boiler, an additional WRAS approved value MUST be
fitted to the mains water supply, up stream of the
double check valve to fully comply with the water
regulations
Water Flow Rate and Pressure Loss
europa
24
28
Max CH Output
kW
24.3
28.0
(Btu/h)
(82,900)
(95,500)
Water flow rate
l/sec
0.38
0.44
(gal/min)
4.9
5.7
Temperature Differential
o
C
15
15
(
o
F)
(27)
(27)
Head available for
m w.g.
2.3
2.3
system pump.
(ft w.g.)
7.5
7.5
DOMESTIC HOT WATER
Domestic Hot Water Requirements
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.
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 200 mg/litre, 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 accommodate the expansion of
DHW contained within the appliance, if a non-return valve is
fitted to the DHW inlet.
C.H. Return
Hose unions
Mains
water supply
Stop valve
Temporary hose
Double check
valve assembly
Additional
isolation
valve
