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PRE-INSTALLATION
4.3.3
External connection considerations
NOTICE: Rainwater or external drain disposal
Untreated condensate must not be allowed to flow into
streams or rivers
▶ A rainwater down pipe or an external drain shall only
be used for condensate disposal it the down pipe or
external drain is connected to a combined foul and
rainwater system
▶ Refer to BS 6798 for more information
NOTICE: Grey water systems
Contamination of recovered water
▶ Condensate disposal shall not be allowed into a grey
water recovery system that is intended for re-use
NOTICE: Freezing conditions
▶ Pipe work length should be kept to a minimum and the
route as vertical as possible.
▶ When required, use only weather proof insulation.
NOTICE: Condensate waste
▶ Care should be taken when siting a soak-away to avoid
causing damage to existing services.
Continued - Key to condensate illustrations, figures 12, 13, 14 &
15
1
Condensate discharge from appliance
7
Condensate pump
8
Pipe work transition
9
Insulate and increase pipe size
10
External rain water pipe into foul water
11
External air break
12
Air gap
13
Strap-on fitting
14
43mm 90° male/female bend
15
100mm Ø minimum plastic pipe
16
Drainage holes
17
Limestone chippings
18
Bottom of sealed tube
19
Increase size of soak away with limestones chippings if in clay
soil area
Table 11 Key to external condensate disposal methods
Condensate drainage pipe can be run above or below
ground. If the pipe work is run under ground, care must
be taken to ensure that the pipe work "fall" towards the
disposal point is maintained
If no other discharge method is possible then the use of an externally run
condensate drainage pipe terminating at a suitable foul water discharge
point, or purpose-designed soak away, may be considered. If this
method is chosen then the following measures should be adopted:
▶ Use a CondenseSure siphon to help prevent the condensate freezing.
▶ The external run be kept as short as possible and not exceed 3
metres.
▶ The pipe should be run internally as far as possible before going
externally and the pipe diameter should be increased to 32mm
before it passes through the wall to the exterior. The pipe should be
insulated using suitable waterproof and weather resistant insulation,
if not using a CondenseSure siphon.
▶ The external pipe should take the shortest and least exposed route to
the discharge point, and should "fall" as steeply as possible away
from the appliance, with no horizontal runs in which condensate
might stand.
18
▶ The use of fittings, elbows etc. should be kept to a minimum and any
internal "burrs" on cut pipe work should be removed so that the
internal pipe section is as smooth as possible.
FITTING AN EXTERNAL AIR BREAK
• Refer to figure 12 when a rain water down pipe is used to dispose of
condensate.
• An air break must be installed in the 43mm pipe work, between the
appliance condensate outlet and the drainpipe, outside the property,
to avoid flooding during adverse weather conditions.
1
22mm Ø
8
Fig. 12 Disposal into a rainwater down pipe
Where the pipe terminates over an open drain or gully, the pipe should
terminate below the grating level, but above water level, in order to
minimise "wind chill" at the open end.
The use of a drain cover (such as those used to prevent blockage by
leaves) may offer further protection from wind chill.
Pipe drainage will be improved if the end is cut at 45° as opposed to a
straight cut.
1
8
Fig. 13 External disposal
8
1
7
Fig. 14 Condensate pump to external disposal
10
9
11
12
13
14
11
9
25mm min.
6720644744-10.4Wo
9
25mm min.
6720644744-12.4Wo
6 720 821 670 (2018/06)
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