Turn every radiator on at handover

Plenty of homes complete in summer with a heating system that has been pressure-tested and commissioned — but never actually run hot, room by room, with someone standing there feeling the panels. Ten minutes with the heating on full tells you more than the commissioning certificate.

How to read a radiator

• Cold at the top, hot at the bottom — trapped air. The fix is bleeding the radiator; routine, but on a brand-new system it can also point to air left in from filling, so it goes on the list.
• Cold at the bottom or in the middle, hot at the top — debris or sludge collecting in the panel. On a new-build this suggests the system wasn't flushed properly before filling. That's a commissioning snag, not maintenance.
• One radiator heats slowly while the rest run hot — the system is out of balance. Balancing is the installer's job, and "the back bedroom never quite warms up" is exactly the kind of thing that gets lived with for years if it isn't logged on day one.
• TRVs — turn every thermostatic valve from closed to full. It should move freely and the radiator should respond. Check valve connections for weeps while you're down there.

Do it the Snagga way

1. Heating on full at the start of your walk-round, every TRV open.
2. By the end of the walk the system is hot — now do a second pass just feeling radiators, top and bottom.
3. Photograph anything suspect (a phone camera can't show cold, so photograph the radiator and describe the cold zone in the note).
4. Log each one against the plumber before you sign anything.

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