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What is cold water corrosion and how to avoid it?

This is the result of water below 40°c being pumped through the boiler jacket. This causes large quantities of condensation to form inside the fire box which can encourage rusting but more importantly, mix with the products of combustion when coal is burnt and form a sulphuric acid, attacking the steel work. This can result in a water jacket failure surprisingly quickly.


We recommend that a pump control pipe thermostat to be fitted on the pumped circuit return flow, set at 45°C disabling the pump until the correct temperature has been reached.