REMEHA 1000 Indirect, Installation Manual

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(b) other material that has been demonstrated to be capable of safely withstanding temperatures of the water discharged and is clearly and
permanently marked to identify the product and performance standard (e.g. as specified in the relevant part of BS 7291).
3.58 The discharge pipe (D2) should 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. for discharge pipes between 9m and 18m the 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 sizes larger, and so on; bends must be
taken into account in calculating the flow resistance. See Fig 12, Table 8 and the worked example.
Note: An alternative approach for sizing discharge pipes would be to follow Annex D, section D.2 of BS 6700:2006 Specification for design,
installation, testing and maintenance of services supplying water for domestic use within buildings and their curtilages.
3.59 Where a single common discharge pipe serves more than one system, it should be at least one pipe size larger than the largest individual
discharge pipe (D2) to be connected.
3.60 The discharge pipe should not be connected to a soil discharge stack unless it can be demonstrated that the soil discharge stack is capable of
safely withstanding temperatures of the water discharged, in which case, it should:
(a) contain a mechanical seal, not incorporating a water trap, which allows water into the branch pipe without allowing foul air from the drain to
be ventilated through the tundish;
(b) be a separate branch pipe with no sanitary appliances connected to it;
(c) if plastic pipes are used as branch pipes carrying discharge from a safety device they should be either polybutylene (PB) to Class S of BS
7291-2:2006 or cross linked polyethylene (PE-X) to Class S of BS 7291-3:2006; and
(d) be continuously marked with a warning that no sanitary appliances should be connected to the pipe.
Note:
1. Plastic pipes should be joined and assembled with fittings appropriate to the circumstances in which they are used as set out in BS EN
ISO 1043-1.
2. Where pipes cannot be connected to the stack it may be possible to route a dedicated pipe alongside or in close proximity to the discharge
stack.
Termination of discharge pipe
3.61 The discharge pipe (D2) from the tundish should terminate in a safe place where there is no risk to persons in the vicinity of the discharge.
3.62 Examples of acceptable discharge arrangements are:
(a) to a trapped gully with the end of the pipe below a fixed grating and above the water seal;
(b) downward discharges at low level; i.e. up to 100mm above external surfaces such as car parks, hard standings, grassed areas etc. are
acceptable providing that a wire cage or similar guard is positioned to prevent contact, whilst maintaining visibility; and
(c) discharges at high level: e.g. into a metal hopper and metal downpipe with the end of the discharge pipe clearly visible or onto a roof capable
of withstanding high temperature discharges of water and 3m from any plastic guttering system that would collect such discharges.