Filling The System; Expansion Vessel - MHG Heating ProCon HT Installation And Operating Manual

10.0 Filling The System

The Initial filling of a sealed heating system, and subsequent refilling, must be by a
method that has been approved by the Water Regulation Advisory Scheme (WRAS) for
that type of heating system.
i.e. Domestic (
Non Domestic (Other than
For Category 3 systems, the approved method of filling must comprise of the following
components in the arrangement shown;
•
Control Valve incorporating a Double
Check Valve on the Mains Cold Water
pipework.
•
Temporary Connecting Hose, which must
be disconnected after use.
•
Control Valve, on the heating system.
For Category 4 systems, the approved method of filling must comprise of the following
components in the arrangement shown;
•
Control Valve.
•
Strainer.
•
Verifiable Backflow Device with Reduced
Pressure Zone (RPZ Valve)
•
Incorporating a 'Type BA' Air Gap.
•
Tundish.
•
Control Valve.
Further more, in accordance with BS 6644: 2005 system with an input greater than 70kW
(nett), an automatic water replenishment unit shall be installed to automatically
replenish any lost or evaporated water.
Please refer to BS 6644: 2005 for allowable water replenishment methods for use with
sealed/pressurized heating systems.
For information on a comprehensive range of pressurization units that comply with
current British Standards and WRAS Regulations, please contact MHG Heating Ltd Sales.

10.1 Expansion Vessel

In accordance with BS 6644: 2005, WRAS Regulations, and Local Authority Water
Regulations, as applicable, the installer shall install a suitably sized, and approved,
Expansion Vessel to ensure that the water capacity of the system has ample expansion
capacity.
The location of the expansion vessel shall only be isolatable from the system via a
Lockable Type Service Valve, which shall be locked in the
accidental isolation.
Furthermore, a drain facility should be provided adjacent to the expansion vessel to
aide the routine maintenance, overhaul, of the vessels Air Pressure setting.
For information on a comprehensive range of expansion vessels that comply with
current British Standards and WRAS Regulations, please contact MHG Heating Ltd Sales.
MHG Heating Ltd, Unit 4 Epsom Downs Metro Centre, Waterfield, Tadworth, Surrey, KT20 5LR
P:0845 6448802 F:0845 6448803 E:
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