© MHG Heating Ltd
39
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
020315 Draft
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.
Furthermore, in accordance with BS 6644: 2011 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: 2011 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.
