Frozen Condensate Pipe: How to Thaw & Prevent

Quick Answer: Pour warm (NOT boiling) water over the frozen section of the condensate pipe, usually where it exits your house. Reset your boiler. Prevent future freezing by lagging the pipe or rerouting internally.

Is It a Frozen Condensate Pipe?

Signs pointing to frozen condensate:

• Boiler showing error code (E28, EA, etc.)
• Gurgling/bubbling sounds from boiler
• Boiler locking out repeatedly
• Cold weather (below 0°C)
• White plastic pipe visible outside

Where to Find the Condensate Pipe

Look for a white/grey plastic pipe (22mm typically) that:

• Exits through an external wall
• Runs along outside of house
• Connects to drain/soil pipe
• Often poorly insulated

How to Thaw It Safely

Step 1: Locate the Frozen Section

Usually at:

• Where pipe exits building
• Bends in the pipe
• Low points where water collects
• End where it discharges

Step 2: Apply Warm Water

Use:

• Warm water from kettle (not boiling)
• Hot water bottles placed on pipe
• Microwaved wheat bag

DO NOT use:

• Boiling water (can crack plastic)
• Heat gun or naked flame
• Anything electrical near water

Step 3: Pour Slowly

• Start from the discharge end
• Work backwards toward the boiler
• Wait for ice to melt gradually
• May need several applications

Step 4: Reset Boiler

• Most need a reset after lockout
• Check manual for specific reset procedure
• May need to press button or turn dial

Preventing Future Freeze-Ups

Lagging the Pipe

Insulate with:

• Pipe lagging (foam)
• Waterproof tape
• Purpose-made condensate jacket

Cost: £10-30 DIY, £50-100 fitted

Rerouting Internally

Longer-term solution:

• Route pipe through internal waste
• Eliminates freezing risk
• Cost: £100-200

Trace Heating

For very exposed pipes:

• Electrical trace heating cable
• Thermostatically controlled
• Cost: £80-150 installed

When to Call a Gas Engineer

Call if:

• Thawing doesn't fix the problem
• Boiler still locks out
• You can't locate the pipe
• Multiple freeze-ups occur

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Boiler repair Glasgow: +44 141 468 9930