ISSUE 2016 Rev 1 - Installation Manual
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ThermaQ
Insulation of the Temperature and Pressure Relief Valve
Components for insulating the TPRV are supplied in order to retain heat and energy. Installation instructions are provided with the insulation
cover.
Discharge Pipework and Tundish
Note: This information is not exhaustive, and if in doubt, seek advice. Full details of Building Regulation G3, is available from:
www.planningportal.gov.uk
The discharge from both the temperature relief and expansion relief valves can be joined together via a 15mm end feed tee. Water should only
be discharged when there is a fault with the system.
The discharge water must not collect in this pipe-work and flow freely to the tundish. This tundish should be vertically mounted in a visible
location in the same space as the hot water storage system, fitted as close as possible with 600mm of the safety device e.g. the temperature
relief valve. The discharge pipework from this tundish must be routed in accordance with part G3 of the Building Regulations.
This discharge should be visible at the tundish. For people with impaired vision or mobility, consider installing a safety device to alert them to
when discharge takes place. For more information in this situation see the building regulations.
a)
The discharge pipe (D2) from the Tundish should have a vertical section of pipe 300mm long below the Tundish before any elbows
or bends in the pipework.
b)
This pipe should then be installed with a continuous fall of at least 1 in 200 thereafter.
c)
The pipe must be at least one pipe size larger than the nominal outlet size of the safety device unless its total equivalent hydraulic
resistance exceeds that of a straight pipe 9m long i.e. discharge pipes between 9m and 18m equivalent resistance length should be at
least two sizes larger than the nominal outlet size of the safety device, between 18 and 27m at least 3 times larger and so on. Bends
must be taken into account in calculating the flow resistance. An alternative approach for sizing discharge pipes would be to follow
BS6700 Specification for the design installation, testing and maintenance of services supplying water for domestic use within
buildings and their curtilages.
From the tundish, pipework should terminate in a safe place where there is no danger to persons in the vicinity of the discharge. Examples of
acceptable discharge arrangements include:
1.
To a trapped gully with the outlet below a fixed grating and above water seal.
2.
Downward discharges to low level, within 100mm, above external surfaces such as a car park, hard standing, grassed area with a
protective wire cage to prevent contact but retaining visibility of discharge.
3.
Discharge at high level into a metal hopper and metal downpipe with the termination point clearly visible or onto a roof capable of
withstanding high temperature discharge and at least 3m away from plastic guttering system.
Building Regulation G3 allows for the usage of non-metallic pipework within the tundish discharge (D2): The discharge pipe (D2) should be
made of a) metal or b) other material that has demonstrated to be capable of safely withstanding high temperatures of water discharges and is
clearly and permanently marked to identify the product and the performance standard. The discharge should not be connected to a soil
discharge stack unless it can be demonstrated of safely withstanding the high temperature of water discharge, in which case it should;
1.
Contain a mechanical seal, not a water trap, which allows water into the branch pipe but not foul air from the drain to be ventilated
through the tundish.
2.
Be a separate branch pipe with no sanitary appliances connected to it.
3.
Plastic pipes used as branch pipes with the discharge should be Polybutylene (PB) or cross linked polythene (PEX) complying with
national standards such as Class S of B7291-2:2006 or Class S of BS7291-3:2006 respectively.
4.
Be continuously marked with a warning that no sanitary appliances should be connected to the pipe.
5.
Plastic pipes should be joined and assembled with fittings appropriate to the circumstances in which they are used as set out in BS
EN 1043-1:2002
The foregoing is an appraisal of Building Regulation detail and it is essential the installer gains knowledge of the full requirements
prior to product installation.
Schematic
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