Heatrae Sadia ELECTROMAX SOLAR Installation & Servicing Instructions Manual page 18

3.5 INSTALLATION DISCHARGE
It is a requirement of Building Regulations that any discharge from an unvented system
should be visible and safely conveyed away from the system without danger to persons in
or about the building where it is installed. The discharge pipe should be fitted in accordance
with the requirements and guidance notes of Building Regulations. Building Regulation G3
Requirements and Guidance section 3.9 are reproduced in the following sections.
Information Sheet No.33 available from the British Board of Agrement gives further advice on
discharge pipe installation. For discharge pipe arrangements not covered by G3 Guidance or
BBA Info sheet No. 33 advice should be sought from either your local Building Control Officer
or Heatrae Sadia. The discharge pipework supplied fitted to the Electromax Solar will convey
any discharge from the unvented cylinder Temperature and Pressure Relief Valve and the
sealed system Pressure Relief Valve. A discharge pipe will also be required from the Expansion
Valve fitted to the Cold Water Combination Valve. Where practical this can be teed into the
discharge pipe from the Electromax. It is recommended that an additional tundish is fitted into
this discharge pipe to give an early indication of operation of the Expansion Valve.
In some instances it may be possible to discharge into an internal waste system and soil stack.
To do this a self sealing waste valve must be fitted into the discharge pipe after the tundish
to prevent foul odours or back-pressurisation from the waste system entering the building via
the tundish. In these systems it is essential that the tundish is fitted in a visible position as the
final point of discharge will not be visible. Consult the manufacturer's recommendations with
respect to the correct fitting, orientation and waste and soil stack materials selection. It will also
be necessary to get dispensation from your local Building Control Officer to discharge in this
manner. Discharges from an unvented system can be up to 95 C for several minutes, ensure
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any waste or soil pipe connected to the discharge can safely accept these conditions.
G3 REQUIREMENT
"...there shall be precautions...to ensure that the hot water discharged from safety devices
is safely conveyed to where it is visible but will not cause danger to persons in or about the
building."
Water may drip from the discharge pipe of the pressure-relief device and that this pipe must
be left open to the atmosphere.
The pressure-relief device is to be operated regularly to remove lime deposits and to verify
that it is not blocked.
The discharge pipe connected to the pressure relief device is to be installed in a continuously
downward direction and in a frost free environment
G3 GUIDANCE SECTION 3.9
The discharge pipe (D1) (see figure 8, page 19) from the vessel up to and including the tundish
is generally supplied by the manufacturer of the hot water storage system. Where otherwise,
the installation should include the discharge pipe(s) (D1) from the safety device(s). In either
case the tundish should be vertical, located in the same space as the unvented hot water
storage system and be fitted as close as possible and within 500mm of the safety device e.g.
the temperature relief valve.
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