Damp on the pipes in the cellar — condensation or a leak?

Cold water pipes and refrigeration lines, especially uninsulated ones, in a space that is warmer and more humid than the pipe. That is why it gets worse in summer and in utility rooms. A hot water or heating pipe does not sweat — if that is wet, it is not condensation.

Water that is running, increasing quickly or standing on the floor should be shut off and dealt with now. Slow damp around a joint can wait for a working day but not for next month — damp in a cellar becomes mould and rot long before the pipe gives up entirely.

White or green deposits and rust marks under a joint mean it has been leaking for some time, even if it looks dry right now. Wipe them away and see whether they come back. That indicates a recurring leak rather than condensation.

Often yes — pipe insulation on cold pipes is the standard measure, alongside better ventilation or dehumidification in the space. But never insulate a pipe before you know it is condensation: insulation over a leak hides it and holds the moisture against the pipe.

The whole pipe run so it is visible whether the damp is even or localised, a close-up of the wettest point, and any deposits. Say whether it is cold or hot water if you know, how long it has been going on, and whether it is worse at certain times of year.

Partly, and the part that is settled is the application key. An ECL Comfort 210 or 310 is an empty shell without one: the key carries the software layout, such as A266 for heating plus domestic hot water. Keys are not locked to a serial number and move freely between controllers of the same type.

Almost always air in the radiator. Hot water comes in and heats the lower part, but air has collected at the top where it cannot escape on its own, so the top stays cold. Bleeding the radiator is the first step and usually fixes it.

There are three common sources, and they can be told apart without tools. The trap and its connections only leak when you run water. The supplies to the tap leak continuously, including overnight, because they are under pressure. The dishwasher hose or connection leaks during and just after a cycle.

Not without knowing what it sits on. A valve can be the isolation for a single tap, for a whole flat, for a heating circuit, or for a system that cannot be left standing — and from the outside they look much alike. A closed heating or circulation circuit can cause frost damage or stagnant hot water long after you have forgotten you touched it.

The heating working while the hot water does not already says a good deal: the fault is usually in the part that only concerns hot water, not in the heat source. The most common are the cylinder or the heat exchanger, a broken or misadjusted mixing valve, or a stopped hot water circulation pump.