Work from the symptom
Three paths, each starting from something you can observe and ending at the note that explains it.
A room will not warm up
Work outward from the heat source. Each step names the observation that sends you to the next one.
- Is the radiator or register warm at all?
If it is cold across its whole face, the problem is delivery, not the room. Check the valve head and pin, or the register damper, before anything else.
Why radiators heat unevenly - Is it warm at the top only, or the bottom only?
A cold top band is trapped gas. A cold bottom band is settled sludge. These are different faults with different remedies.
Why radiators heat unevenly - Do the rooms nearest the plant run hot while this one never arrives?
That is a distribution problem across the whole system, corrected by balancing rather than by anything done in this room.
Balancing forced-air registers
A damp patch appeared
Order the checks by where the patch sits relative to anything that could be wetting it.
- Is there anything above the patch that carries water?
A pipe, a bathroom, a valley or a parapet above the patch makes an internal leak the first thing to rule out, because it is the only source that is indifferent to weather.
Diagnosing damp in a basement wall - Does the patch respond to rain within a day or two?
That points outside the wall: ground level, a gulley, a downpipe or a path falling toward the building.
Diagnosing damp in a basement wall - Does it have a level upper edge and ignore the weather?
Moisture moving up through the structure behaves that way. Check the external ground level against the internal floor before anything else.
Diagnosing damp in a basement wall
A window rattles and draughts
Work from the meeting rail outward to the frame perimeter, because the inner faults are both commoner and cheaper.
- Do the two sashes move against each other at the meeting rail?
That is the commonest single source of both the rattle and the draught, and it is adjustment work rather than replacement.
Repair or replace old sash windows - Does the sash move sideways within the frame?
The parting bead or the staff bead has worn or been replaced too thin. Both are removable and replaceable without touching the sash.
Repair or replace old sash windows - Do the sashes run at all, or are they painted shut?
A seized sash is usually paint or a broken cord, and neither is a reason to consider the window failed.
Repair or replace old sash windows