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7.0 Site Requirements
18
© Baxi Heating UK Ltd 2009
7.6
Condensate Drain
FAILURE TO INSTALL THE CONDENSATE
DISCHARGE PIPEWORK CORRECTLY WILL AFFECT
THE RELIABLE OPERATION OF THE BOILER
The condensate discharge pipe MUST NOT RISE at any
point along its length. There MUST be a fall of AT LEAST
2.5° (50mm per metre) along the entire run.
NOTE: It is unnecessary to fit an air break in the discharge
pipe.
1. The condensate outlet terminates in a 1” BSP nut and seal for
the connection of 21.5mm (
3
/
4
in) plastic overflow pipe which
should generally discharge internally into the household drainage
system. If this is not possible, discharge into an outside drain is
acceptable.
2. Ensure the discharge of condensate complies with any
national or local regulations in force.
BS 6798 & Part H1 of the Building Regulations give further
guidance.
3. The discharge pipe should be run in a proprietary drain pipe
material e.g. PVC, PVC-U, ABS, PVC-C or PP.
4. Metal pipework is NOT suitable for use in condensate
discharge systems.
5. The pipe should be a minimum of 21.5mm diameter and
must be supported using suitably spaced clips to prevent
sagging.
6.
It is advisable to keep the condensate pipe internal.
7.
External runs greater than 3 metres or runs in cold areas
should use 32mm waste pipe.
8. If the boiler is fitted in an unheated location the entire
condensate discharge pipe should be treated as an external run.
9. In all cases discharge pipe must be installed to aid disposal of
the condensate. To reduce the risk of condensate being
trapped, as few bends and fittings as possible should be used.
10. When discharging condensate into a soil stack or waste pipe
the effects of existing plumbing must be considered. If soil pipes
or waste pipes are subjected to internal pressure fluctuations
when WC's are flushed or sinks emptied then back-pressure
may force water out of the boiler trap and cause appliance
lockout.
Examples are shown of the following methods of termination:-
i) to an internal soil & vent pipe
ii) via an internal discharge branch (e.g. sink waste)
iii) to a drain or gully
iv) to a purpose made soakaway
It is also permissible to discharge into a downpipe carrying
rainwater, providing this pipe connects to a foul water drain.
Boiler
2.5° Minimum fall
Termination to an internal soil and
vent pipe
450mm min
Boiler
2.5° Minimum fall
External termination via internal discharge
branch
e.g sink waste - downstream
Sink
Pipe must terminate
above water level but
below surrounding
surface
Boiler
Pipe must terminate above
water level but below
surrounding surface
2.5° Minimum fall
Termination to a drain or gully
Boiler
500mm min
2.5° Minimum fall
Termination to a purpose made soak-
away
Holes in the soak-away must
face away from the building
50mm per metre of pipe run
50mm per metre of pipe run
50mm per metre of pipe run
50mm per metre of pipe run