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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:
• Into a soil stack – either directly or
via an existing waste system
• Into an external gulley
MCS Product Certification Scheme
Requirements for Biomass (MCS 008)
state that:
“
Because of the volume of wash-
down/condensate discharge, it is NOT
recommended to discharge 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 or hopper. Every
Grant Spira boiler is supplied with a
trap and this MUST be used. Refer to
Section 5.5 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 can be
connected directly into 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.
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 60 (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 system of the boiler
which could exceed the capabilities
of the tank and condensate pump.
Refer to Section 9 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 system
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 ‘external’.
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