Condensate
Disposal
20
5 Condensate Disposal
5.1 General Requirements
When in condensing mode the Grant
SPIRA condensing wood pellet boilers
produce condensate from the water
vapour in the flue gases. This
condensate is slightly acidic with a ph
value of around 6. Provision must be
made for the safe and effective disposal
of this condensate.
Condensate can be disposed using one
of the following methods:
a) Into a soil stack – either directly or
via an existing waste system.
b) Into an external gulley.
c) Into a purpose made soakaway.
All condensate disposal pipes must
be fitted with a trap whether they are
connected internally or externally to a
domestic waste system/soil stack or
run externally to a gully, hopper or
soakaway. Every Grant SPIRA boiler is
supplied with a trap and this MUST be
used. Refer to Section 5.6 for trap
details.
5.2 Connections
Connections into a rainwater hopper,
external drain or gulley should be
terminated inside the hopper/drain/
gulley below the grid level but above
the water level.
Condensate disposal pipes must not
be connected directly into rainwater
downpipes or to waste/soil systems
connected to septic tanks.
Condensate must not be discharged
into ‘grey water’ systems that re-use
water used in the home (not including
water from toilets).
It should be noted that connection of a
condensate pipe to the drain may be
subject to local Building Control.
5.3 Pipework
Condensate disposal pipework must be
plastic. Copper or steel pipe is not
suitable and must NOT be used.
All condensate disposal pipes
connected to a Grant SPIRA boiler
must have a minimum ‘nominal’
diameter of 38mm (1 ½”) plastic pipe.
Condensate disposal pipes should be
kept as short as possible and the
number of bends kept to a minimum.
Pipes should be adequately fixed to
prevent sagging, i.e. at no more than
0.5 metre intervals.
Condensate disposal pipes must be
fitted with a fall (away from the boiler) of
at least 2.5° (~45mm fall per metre run).
5.4 External Pipework
Ideally, external pipework, or pipework
in unheated areas, should be avoided. If
unavoidable, external pipework should
be kept as short as possible (less than
3 metres) and 38mm (1½”) waste pipe
used to minimise the risk of ice blocking
the pipe in freezing conditions.
The number of bends, fitting and joints
on external pipes should be kept to a
minimum to reduce the risk of trapping
condensate.
5.5 Condensate Soakaway
To keep external pipework to a
minimum, locate the soak away as
close as possible to the boiler but
ensure it is at least 1 metre from
building foundations and away from
other services, for example gas,
electricity or other services.
The condensate pipe may be run above
or below ground level and can enter
either the top or side of the soakaway
tube. Refer to Figure 5.1.
Ensure that the drainage holes in the
soakaway tube face away from the
building.
Backfill the soakaway tube, and the
hole around it, with 10mm limestone
chippings.
Only use a soakaway where the soil
is porous and drains easily.
When using a condensate pump and
holding tank, the burner settings for
‘TIME CLEAN PERIOD’ (time boiler
cleaning is in operation) must not be
set greater than 600 (60 seconds)
and the ‘TIME CLEAN BOILER’ (time
between boiler cleaning operations)
must not be set less than 180
minutes, as modifying these times
could result in larger and more
frequent wash down of the boiler
which could exceed the capabilities
of the tank and condensate pump.
Refer to Section 8 for further details
of the burner settings.
!
WARNING
!
NOTE
Where it is not possible for the pipe
to fall towards the point of discharge
–either internally into a waste system
or externally to a gulley (e.g. for
boilers installed in a basement), it
will be necessary to use a
condensate pump.
When using a condensate pump with
a Grant SPIRA boiler, a condensate
holding tank of at least 40 litres is
required. This is to ensure that when
the boiler cleaning cycle has
operated the holding tank can collect
the total volume of the water used in
the wash down and the condensate
pump can then discharge the waste
water effectively.
A boiler interlock should be fitted to
shut off the boiler in the event of a
malfunction of the condensate pump.
!
NOTE
For a boiler installed in an unheated
area such as an outhouse or garage,
all condensate pipework should be
considered as an ‘external’.
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