Boiler

Appliance heating water for space heating or domestic use.

Symptoms around this component

Compare staining, odor, sound, temperature and movement with the component operating cycle and nearby materials.

What to document

Photograph the component and the surrounding assembly, note weather or equipment conditions and record whether the symptom is active or historic.

Repair boundary

A visible component may be only one part of a layered detail. Verify interfaces and drainage paths before replacing it in isolation.