Condensate routing: how a suitable drainage point is chosen
All modern condensing boilers produce a small but steady amount of mildly acidic condensate that needs draining somewhere suitable, and finding that route is part of every survey rather than an afterthought once the boiler is fitted. The best route depends entirely on the specific property's drainage layout.
The engineering behind condensate routing
An internal route to an existing waste pipe is usually preferred where one is conveniently placed, since it avoids an external run being exposed to freezing conditions. Where no internal route is practical, an external pipe is used, sized and insulated to reduce freeze risk, with a continuous fall to a suitable external gully or soakaway. Rural properties on septic systems or soakaways need their specific drainage arrangement considered separately.
Key points on condensate routing
- Internal routes to an existing waste pipe are generally preferred where practical
- External condensate pipes need proper insulation to reduce freeze risk
- A continuous fall is required along the whole condensate route
- Septic tank or soakaway properties need their drainage layout checked specifically
- Condensate pipe sizing follows manufacturer and industry guidance
Where we deal with this
Relevant registrations
- Gas Safe registered for domestic gas boiler work
- OFTEC registered for oil boiler work
- Worcester Bosch Accredited Installer
Book a visit for condensate routing
The honest position: Condensate routing is planned around the property's actual drainage layout at survey stage, balancing internal convenience against freeze risk.
Jamie Crawford Heating is based at 24 Bristol Road, Radstock, BA3 3EE.
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Questions we get asked
- Why do external condensate pipes sometimes freeze?
- They are more exposed to cold than internal routes, which is why proper insulation and pipe sizing matter for external runs.
- Can condensate go into any drain?
- It needs a suitable foul drainage connection — surface water only drains are generally not appropriate.
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