Product guide

Timeguard NTT03 24-hour/7-day immersion heater timeswitch

Timeguard NTT03 is a compact electronic timeswitch for domestic immersion heaters, with daily or weekly scheduling and short boost controls. Its programme flexibility and power-cut clock backup suit households with changing hot-water routines, while installation is recommended for a qualified electrician.

At a glance

Set up to four on/off periods per day, with the same schedule every day, a weekday/weekend split or separate daily programmes.
A one- or two-hour boost is available at the button, and advance/override controls can skip to the next programme or hold output on or off.
The built-in rechargeable battery is claimed to preserve the clock and programmes during a power cut.
Programme review, an illuminated screen and power/output LEDs make settings and output status easier to check.

Price

£31.15Save 11%

Reference price: ~~£34.99~~

Price checked: 12 Nov 2026

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Pros and cons

Pros

Flexible weekly scheduling supports routines that vary between weekdays and weekends.
Short boost options provide a timed way to add hot water without changing the regular schedule.
Power-cut clock and programme backup reduces the need to re-enter settings after an interruption.

Cons

Installation is recommended to be carried out by a qualified electrician, so this is not presented as a simple plug-in timer.

Technical specifications

17 specifications

Identity
Brand	Timeguard
Model	NTT03

Programming and operation
Scheduling	24-Hour/7-Day
Daily programme periods	4 ON/OFF periods per day
Schedule options	every day the same, weekdays and weekends separately (5+2), or each day individually
Switching interval	accurate to the minute
Output rating	16A resistive loads
Clock backup	A built-in rechargeable battery keeps the clock running and your programmes saved during a power cut.
Automatic seasonal time change	Optional automatic summer/winter time changeover
Display and indicators	illuminated screen and power and output LEDs
Control output	Digital
Maximum time	168H

Electrical
Voltage	230 Volts

Dimensions and installation
Dimensions listed	11.7 x 16.9 x 23.2 cm; 171.1 g
Weight listed	171 g
Wall box fit	single gang wall box with a minimum depth of 32mm

Materials and protection
Material listed	Plastic

What to know before buying

Listing details to confirm

The listing says the timer is not suitable for discharge lighting. Confirm the existing wall box and installation requirements with a qualified electrician before fitting.

Who is it for?

A good fit for

Households using a domestic immersion heater that want recurring weekday, weekend or day-by-day schedules.
Buyers who want timed boost and advance/override controls alongside a regular programme.

Less suited to

Anyone seeking a plug-in timer or a product described as suitable for discharge lighting.

Customer reviews on Amazon

4.3 / 5 · 1,366 ratings

5 stars68%68%
4 stars18%18%
3 stars4%4%
2 stars3%3%
1 star7%7%

The aggregate ratings lean positive, with a majority in the five-star category, but a smaller share of ratings are low. Ratings alone do not explain why customers scored it that way. For buyers considering its stated weekly scheduling and boost controls, the figures offer a broad satisfaction signal rather than evidence about installation ease or performance in a particular setup.

Frequently asked questions

Can the NTT03 use different schedules on different days?

The listing describes four on/off periods per day and allows a repeated daily schedule, a weekday/weekend split or individual programmes for each day.

How does the boost function work?

The listing describes a one-hour boost with one press and a two-hour boost with two presses, after which the heater switches off automatically.

Does it retain its settings during a power cut?

The listing claims its built-in rechargeable battery keeps the clock running and programmes saved during a power cut.

Is professional installation recommended?

Yes. The listing recommends installation by a qualified electrician and says the timer fits a single gang wall box with a minimum depth of 32mm.