Quick answer
How is external pipework protected against freezing?
External and frost-vulnerable pipework is protected with electric trace heating fitted directly to the pipe, with thermal insulation over the top. A thermostat switches the heating cable on as air temperature approaches freezing, keeping the pipe above zero. Insulation alone only slows freezing; trace heating with insulation prevents it.
Which pipes are at risk of freezing?
External runs, roof plant feeds, make-up and dosing lines, and any pipework in unheated spaces such as lofts, risers and garage levels. Pipes that only flow intermittently are most vulnerable, because still water freezes faster than moving water.
Why isn't insulation alone enough?
Insulation slows heat loss but does not add heat. Given a long enough cold spell, the water inside an insulated pipe will still reach freezing point. For reliable protection, a heat source is needed — which is where electric trace heating comes in.
How does electric trace heating work?
A heating cable is fixed along the pipe before the insulation goes on. When energised it warms the pipe wall just enough to keep the contents above freezing. The insulation over the cable holds that heat in, so the cable runs for short periods rather than continuously.
How is trace heating controlled?
An ambient or line-sensing thermostat switches the circuit on as temperature falls towards freezing and off again above it. Self-regulating cable adjusts its own output along its length. Controls are mounted accessibly and labelled so facilities teams can check status at a glance.
What detailing matters on external runs?
External trace-heated pipework also needs a weatherproof finish over the insulation — aluminium cladding or PIB — so rain cannot saturate the insulation and strip out the heat. Valves and fittings on the run are trace heated and jacketed too, because they freeze first.
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