External condensate connections

Freezing conditions

Pipe work length should be kept to a minimum and the route as vertical as possible
Where pipe work is subjected to extreme cold or wind chill, a weather proof insulation should be used

Condensate waste

Care should be taken when siting a soak away to avoid obstructing existing services

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:

The external run be kept as short as possible and not exceed three 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
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 boiler, with no horizontal runs in which condensate might stand
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 4. When a rain water down pipe, that goes directly into a sewer that carries both rainwater and foul water, is used to dispose of the condensate
An air break must be installed in the 43mm pipe work, between the boiler condensate outlet and the drainpipe, outside the property, to avoid flooding during adverse weather conditions

Condensate drainage pipe can be run above or below ground.

Where the pipe terminates over an open drain or gulley, 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 45º angle as opposed to a straight cut. (see fig.5)

Condensate soak away

The condensate drainage pipe may be run above or below the ground to soak away
The examples shown on this page run above the ground
The soak away must use a 100mm dia. plastic tube with two rows of three 12mm holes on 25mm centres and 50mm from the bottom of the tube. The holes must face away from the house
The tube must be surrounded by at least 100mm of limestone chippings to a depth of 400mm

Minimum hole size for the condensate soak away must be 400mm deep by 300mm dia.

In situations where there are likely to be extremes of temperature or exposure, the use of a proprietary trace heating system for external pipe work, incorporating an external frost thermostat, should be considered. If such a system is used, the requirement to use 32mm pipe does not apply, however all other guidance above, and the instructions for the trace heating system, should be closely followed.

Unheated internal areas