Timeguard FST24 24-Hour Fused Spur Timeswitch

In-Depth Look

The Timeguard FST24 puts an immersion heater or other hardwired appliance on a daily timer from the fused spur position, without a separate time clock or smart controller.

How It Works

The FST24 replaces a standard fused connection unit on the wall. A digital timer switches the connected load on and off on a 24-hour daily program, with up to 4 ON and 4 OFF periods and a shortest switching time of 1 minute. A 1 or 2 hour boost and a self-cancelling override let you run the load outside the set times. A rechargeable battery keeps the clock running through short power cuts.

Typical Applications

The most common use is controlling an immersion heater on an off-peak tariff such as Economy 7, so that hot water is heated during the off-peak hours. It can also time other fixed loads within its rating, such as a towel rail. For storage heaters, check the heater instructions first. LED indicators on the front show mains on and when the output is switched.

Summary

The Timeguard FST24 adds a daily digital timer with boost and override to a fused spur position. Check the back box depth and the load rating in the instructions before buying, and have it fitted by a competent person.

How It Compares

The Timeguard FST24 is a timed fused spur that replaces a single-gang fused connection unit. It holds a BS 1362 13A fuse that can be replaced from the front. It runs a 24-hour daily program with up to 4 ON and 4 OFF periods, and the shortest switching time is 1 minute. A digital display shows the clock and timer, there is an optional 1 or 2 hour boost, and a self-cancelling override. It also has a summer and winter changeover, LED indicators for mains on and output, and double-pole switching. It is described as suitable for up to 3kW immersion heaters. A non-replaceable rechargeable battery keeps the time through short power cuts.

The table compares it with other ways of timing a fixed load.

Connectors are one of the accessories used when wiring. For a connector option, see the Wago 221 lever connector box.

Check the depth of the back box in the instructions before you buy, because the timer needs space behind it.

Common Questions

What loads is a fused spur timer meant for? This one is described as suitable for up to 3kW immersion heaters. Check the rating of your heater before you fit it. For storage heaters, check the load and follow the heater maker’s instructions, as they may advise a different arrangement.

Do I need an electrician to replace a spur? The circuit must be isolated and proved dead before you work on it. Use a competent person where required. In England, Part P of the Building Regulations requires new circuits and some work in special locations, such as bathrooms, to be notified, while replacing an accessory like for like is generally not notifiable. Rules differ elsewhere in the UK, so ask building control or a registered electrician if you are unsure. Follow the manufacturer’s instructions.

How do I set the timer? You set up to 4 ON and 4 OFF periods across a 24-hour day. The boost runs the output for 1 or 2 hours, and the override cancels itself. Read the instructions for the exact button sequence.

What does an immersion timer do on a time-of-use tariff? It heats the water during the periods you choose, so you can match it to the times your tariff applies. Check the tariff times with your electricity supplier, and check the timer’s clock is correct after a power cut or a clock change.

Does it need a bigger back box? Check the depth in the instructions. Datasheet figures vary, so do not rely on a number from another page. Follow the manufacturer’s instructions and use a competent person where required.