© MHG Heating Ltd
64
MHG Heating Ltd Unit 4 Epsom Downs Metro Centre, Waterfield, Tadworth, Surrey KT20 5LR
Telephone 08456 448802 Fax 08456 448803 Email
Web www.mhgheating.co.uk
140116
11.0 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 (
In-House
)
Fluid Category 3 (
C-3
)
Non Domestic (Other than
In-House
)
Fluid Category 4 (
C-4
)
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.
11.1 Expansion Vessel
In accordance with BS 6644: 2005, WRAS Regulations, and Local Authority Water Regulations, as
applicable, the boiler is supplied with a 10L internal Expansion Vessel to ensure that the water capacity of
the system has ample expansion capacity.
If additional expansion is required due to the size of the system 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
OPEN
position, to prevent accidental isolation.
Furthermore, a drain facility should be provided adjacent to the expansion vessel to aid 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.
