15
4.6 CENTRAL HEATING SYSTEM - Fig. 4.4
The boiler is designed for use in a sealed central heating system in accordance with the requirements of BS EN 12828 and BS 6798.
The system should be designed to operate with flow temperatures of up to 82°C. When designing the system, the pump
head, expansion vessel size, mean radiator temperature, etc. must all be taken into account. Refer to the pump performance
table for guidelines.
System volume -
The expansion vessel incorporated into the boiler is suitable for a sealed heating system with a
maximum water content of 80 litres (18 gal). Above 80 litres, consideration should be given to fitting an additional
expansion vessel fitted in the position shown in Fig. 4.4. To check correct operation of the expansion vessel(s)
the system pressure should not be more than 2.5 bar when the system is at maximum operating temperature (for
further guidance refer to BS 7074:1).
The boiler is supplied with the following components built in:-
Pressure relief valve -
complying with BS 6759 and set to operate at 3 bar. The discharge pipe must be routed clear of the
boiler and terminated in such a manner that it can be seen, but cannot cause injury to persons or property.
Pressure gauge -
To indicate the system pressure to be maintained.
Expansion vessel -
Conforming to BS 4814 with a capacity of 8 litres and pre-charged to a pressure of 0.8 bar.
By-pass -
The boiler incorporates an automatic by-pass, however, if external zone valves are fitted an additional external
by-pass must be fitted
4.7
FILLING THE CENTRAL HEATING SYSTEM - Fig. 4.5
The system design pressure (cold) should be set to 1.0 bar. This pressure is equivalent to a static head (see Fig. 4.4) of 10.2
metres of water.
Provision must be made for filling the system. This is done by the use of a filling loop. See Fig. 4.5.
A filling loop is supplied factory fitted to the InTec GS models.
Filling of the system must be carried out in a manner approved by the local Water Undertaking. Where allowed, the system
may be filled via a temporary connection as shown in Fig. 4.5. After filling, always disconnect the flexible hose of the filling
loop.
All fittings used in the system must be able to withstand pressures up to 3 bar.
Drain taps (to BS 2879) must be used to allow the system to be completely drained.
Fig. 4.4
Fig. 4.5
Filling loop
temporarily connected
Heating circuit
return
Mains
water
supply
Stop
valve
Hose
unions
Stop
valve
Double check
valve assembly
Test cock
Alpha InTec 40GS2 - General Boiler Information
Note:
A drain tap should be installed at the lowest point
of the heating circuit and beneath the appliance.
System
drain tap
Note:
If the mains is fitted with water
meter, check valves or loose jumper stop
cock, then a DHW expansion device must
be fitted.
Static head of system
DHW outlet
Mains water inlet
Additional expansion
vessel (if required)
Automatic
air vent
Boiler
casing
Heating flow
Heating return
Filling point
