Potterton Suprima 100L, Installation & Service Instructions Manual

Page: 9 / 100

Supplied By www.heating spares.co Tel. 0161 620 6677
Publication No. 5102696
9 Installation Requirements
1.9 The System
Before installing a new boiler to an existing system treat the
system with an appropriate descaling/flushing agent as per
the instructions supplied with the treatment package. It is
recommended that any corrosion inhibitors and descalers/
flushing agents used are manufactured by Fernox or
BetzDearborn.
If plastic pipe is used for the central heating circuit there
must be a run of at least 2m of uninsulated copper pipe from
the boiler flow and return connections.
The boiler must be used on Indirect Fully Pumped systems
only, which may be sealed or open vented - See Page 12
for pump requirements.
The system should be designed so that the maximum static
head does not exceed 30.5 m (100 ft) and a minimum of 150
mm (6 in). The flow pipe from the boiler must always be level
to or higher than the return pipe.
On all systems the pump live connection should be wired
to the boiler terminal block, it will then be controlled by the
pump over-run. This will ensure that the pump will continue
to run after boiler shut down if the water temperature is high,
thus preventing nuisance operation of the overheat
thermostat.
It is important that where electrically operated zone valves
are used the boiler is wired so it does not cycle when the
zone valves are closed. Also, systems fitted with controls
that close both hot water and central heating circuits while
the boiler is still hot, must be fitted with a by-pass circuit to
dissipate the residual heat from within the boiler.
If a three port valve is used as shown in Fig. 5 a by-pass is
not necessary since one circuit is always open.
Where a pair of two port valves are used, a by-pass is
necessary. The total length of the by-pass circuit taken
from the boiler connections should be greater than 4 metres
of 22 mm pipe. It should be fitted with a lockshield valve and
be adjusted to maintain a minimum flow through the boiler
of 4.5 litres/min (1 gal/min).
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 (2 m min. length
of 22 mm dia. pipe) and capable of 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. 5. 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 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/in²) shall be used. It must comply
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/in²) shall be fitted to the
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 15 mm. 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 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: 2.1 litres
Small Bore Pipework: 1 litre per kW of system
output
Micro Bore Pipework: 7 litres
Steel Panel Radiators: 8 litres per kW of system
output
Low Water Capacity Radiators: 2 litres per kW of system
output
Hot Water Cylinder: 2 litres