10 / EN
The model 30L is covered under part G3 of the Building Regulations and therefore it is not permissible
to accommodate the expansion water within the system pipe work and consequently a set of expansion
controls must be installed.
Note: The discharge pipework from both relief valves must be made so that an fault is visible to the end
user therefore a tundish (Kit C) is required for the 30L unit and is recommended for 10 and 15 litre units
Please note that in all cases the dielectric junctions must be connected to the heater before any
other connection is made (these prevent an electrolytic reaction).
Only the use of copper pipe is recommended for connection to the heater. If any other material is
used it must be able to withstand 90°C at 7 bar pressure for long periods.
No valves must be fitted between the expansion and pressure relief valves at any point along any of
the safety relief pipework.
All other required safety components to install the model 30L are supplied as a kit with the applian-
ce: 15mm pressure reducing valve set at 3.5 bar.
Expansion vessel (charge pressure set at 3.5bar).
c) DISCHARGE PIPE WORK NOTE:
The following refers to Building Regulations G3. It is mandatory to follow these rules for all relief
valve discharge pipe work.
1) The tundish should be vertical, located in the same space as the unvented hot water storage system
and be fitted as close as possible to, and lower than, the safety device, with no more than 600mm of
pipe between the valve outlet and the tundish
2) Discharge pipes from the temperature & pressure relief and pressure relief valve may be joined
together. The pressure reducing valve should be installed between the nearest draw o and the
non-return valve.
3) The pipe diameter of the D2 pipework must be at least one pipe size larger than the nominal outlet
size of the safety device unless it’s total equivalent hydraulic resistance exceeds that of a straight pipe
9 m long. i.e. Discharge pipes between 9 m and 18 m equivalent resistance length should be at least 2
sizes larger than the nominal outlet size of the safety device. Between 18 m and 27 m at least 3 times
larger, and so on. Bends must be taken into account in calculating the flow resistance. See fig. 5 and
Table 2.
DISCHARGE
TO DRAIN
COLD
HOT
SUPPLY TO OTHER
PARTS OF PLUMBING
SYSTEM
KIT A NON-RETURN VALVE
DIELECTRIC JUNCTIONS
PRESSURE RELIEF
VALVE (6 bar)
TEMPERATURE & PRESSURE
RELIEF VALVE (7 Bar / 90°C)
NEAREST COLD
WATER DRAW-OFF
ISOLATING VALVE
(FIXED JUMPER OR 1/4
TURN BALL TYPE)
KIT B PRESSURE REDUCING
VALVE (SET AT 3.5 bar)
KIT A EXPANSION VESSEL
(CHARGE AT SET 3.5 bar)
COLD WATER
MAINS
TUNDISH
Fig. 3 (Models 30L)
The tundish must be installed away from electrical devices.
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