Sealed Systems - Potterton Suprima 30 Installation And Service Instructions Manual

Installation Requirements - Page 9
Systems fitted with controls which allow the boiler to operate
when both the hot water and central heating circuits are
closed i.e. mechanically operated thermostatic control
valves, must be fitted with a by-pass circuit of:-
1. A minimum length of bypass of 2m of 22mm dia. Pipe.
2. Maintaining a minimum water flow rate through the
boiler of 9 litres/min (2 gal/min).
A suggested method of meeting these requirements by using
a bathroom radiator fitted with two lockshield valves is
shown in Fig. 3.
Additional system information can be found in the Control
Systems, pipework and Wiring Guide.
Drain off taps should be fitted in the pipework close to the
boiler and in the low points of the system.
Note: Although the system can be emptied using the drain
off taps installed in the pipework around the system, to
empty the boiler it is necessary to remove the drain off screw
positioned on the heat exchanger.

Sealed Systems

Note: If the sealed system kit (Part No. 238027) is Not being
used the installation must comply with the following
requirements.
Installation
The installation must comply with the requirements of BS
6798: 1987 and BS 5449: Pt 1. The British Gas publication
"British Gas Specification for Domestic Wet Central Heating
Systems" should also be consulted.
Pressure Relief Valve
A non-adjustable spring-loaded pressure relief valve, preset
to operate at 3 bar (45lbf/in
with BS 6759: Pt 1. and include a manual testing device. It
shall be positioned in the flow pipe either horizontally or
vertically upwards and close to the boiler. No shut-off valves
are to be placed between the boiler and the safety valve.
The valve should be installed with a discharge pipe which
permits the safe discharge of steam and hot water such that
no hazard to persons or damage to electrical components is
caused.
Pressure Gauge
A pressure gauge incorporating a fill pressure indicator,
covering the range 0 - 4 bar (60 lbf/in
system. It should be connected to the system, preferably at
the same point as the expansion vessel. Its location should
be visible from the filling point.
Expansion Vessel
A diaphragm type expansion vessel to BS 4814: Pt 1. Shall
be fitted close to the inlet side of the pump. The connecting
pipework should not be less than 15mm. Pipework
connecting the expansion vessel should not incorporate
valves of any sort. Methods of supporting the vessel are
supplied by the vessel manufacturer. The nitrogen or air
charge pressure of the expansion vessel shall not be less
than the hydrostatic head, (height of the top point of the
system above the expansion vessel). To size the
2
) shall be used. It must comply
2
) shall be fitted to the
Expansion vessel it is first necessary to calculate the volume
of water in the system in litres. The following volumes may
be used as a conservative guide to calculating the system
volume.
Boiler Heat Exchanger:
Small Bore Pipework:
Micro Bore Pipework:
Steel Panel Radiators:
Low Water Capacity Radiators:
Hot Water Cylinder:
If the system is extended, the expansion vessel volume may
have to be increased unless provision has been made for
extension. Where a vessel of the calculated size is not
available, the next available larger size should be used. The
boiler flow temperature is controlled at approximately 82°C.
The vessel size can now be determined from the information
in Table 1 where V = System volume in litres.
Vessel Charge Pressure (bar)
Initial System Pressure (bar)
Expansion Vessel Volume (litres)
cylinder fitted with an immersion calorifier suitable for
operating at a gauge pressure of 0.3 bar (5 lbf/in
of safety valve setting. Single feed indirect cylinders are not
suitable for sealed systems.
Method of Make-up
Provision shall be made for replacing water loss from the
system either:-
i) from a make-up vessel or tank mounted in a position
higher than the top point of the system, and
connected through a non-return valve to the system
on the return side of the hot water cylinder or the
return side of all heat emitters.
or
ii) where access to a make-up vessel would be difficult
by using the mains top up method or a remote
automatic pressurisation and make-up unit as shown
in Figs. 5 & 6.
Mains Connection
There shall be no connection to the mains water supply or to
the water storage tank which supplies domestic hot water
even though a non-return valve, without the approval of the
Local Water Authority.
Filling Point
The system shall be fitted with a filling point at low level
which incorporates a stop valve to BS 1010 and a double
check valve (approved by the National Water Council) to be
fitted in this order from the system mains, see Fig. 5.
2.1 litres
1 litre per kW of system
output
7 litres
8 litres per kW of system
output
2 litres per kW of system
output
2 litres
0.5
1.0
V x 0.11 V x 0.087
Table 1.
2
) in excess
1.5
1.0