No: underfloor heating does not always have to run 24 hours a day. But switching it off whenever you leave is not automatically best either. The right schedule depends on the heat source, floor construction, building heat loss, controller logic, occupancy and required comfort.

Continuous comfort is not continuous heating output

A thermostat can remain set to a comfortable target for most of the day while calling for heat only intermittently. Likewise, a long permitted operating window does not necessarily mean a boiler or heat pump is delivering full output constantly.

A wet underfloor system embedded in heavy screed can respond slowly because the floor stores energy. A lightweight overlay may respond faster. An electric bathroom mat can have very different costs and controls from a water system supplied by a heat pump.

A universal ‘always on saves money’ rule ignores those differences.

Four questions before choosing a programme

  1. When must the room be comfortable? Write the times people actually use it rather than starting with the heating-on time.
  2. How long does this room respond? Use the manufacturer’s guidance and your own observations on reasonably comparable days. Do not assume every floor warms in the same number of minutes.
  3. What produces the heat? Boiler, heat pump and electric resistance systems respond to operating conditions differently. Some heat-pump control strategies are commissioned for stable low-temperature operation.
  4. What does the controller’s time mean? It may start a programmed target at the stated time or aim to meet comfort by that time through adaptive start.

Do not alter an installer-protected heating curve, mixing valve, flow limit or manifold balancing to accelerate a room.

What is a setback?

A setback is a lower target temperature during sleep or absence, rather than a complete shutdown. A lower indoor temperature can reduce building heat loss while it remains lower, but recovering comfort takes time and energy. Heat-source efficiency and other controls affect the comparison.

A big nighttime setback in a heavy floor may lead to a cold breakfast. No setback may be appropriate for some commissioned strategies. Neither approach is guaranteed cheaper for a particular house.

Never choose a setting that creates unsafe cold, damp, condensation, freezing risks or unsuitable conditions for occupants.

Compare a schedule change sensibly

If your exact user manual permits schedule changes and comfort/safety conditions allow it:

  • Save the existing programme so you can restore it.
  • Log actual room temperatures and when comfort is reached across several relevant days.
  • Change one small, reversible ordinary user setting.
  • Observe the outcome under reasonably comparable weather and routines.
  • Track actual energy readings where possible, but also note hot-water use, occupancy and tariffs.
  • Conclude ‘comfort improved’ only where observations support that; do not claim a percentage energy saving without adequate evidence.

Comparing one mild week with a colder week does not isolate the effect of a timetable change. Equally, a bill containing domestic hot water and cooking energy is not a direct underfloor-only meter.

See the thermostat guide and how to assess UK running costs. The two-page schedule experiment in Living With Underfloor Heating is designed to record a defensible comfort result without inventing savings.