Thermostat socket buying guide

Updated: October 2026

You have a heater, a fan, or a heat mat in one hand and a wall socket in the other, and the listing does not agree with itself. One line says 13 A, another says 16 A, and a wattage figure can be physically impossible. A thermostat socket sits in a BS 1363 socket and lets a wired probe decide when the relay closes. Decide a load you can reconcile with 13 A, then the probe, then one temperature, a day and night pair, or two outputs. Prices in the thermostat plug socket comparison run from £11.99 to £39.99. Button presses stay on the how-to page. Listings were compared in October 2026. We did not run a lab test.

Our top picks

Badge	Product	Load	Probe	Day and night	Note	Price	Offer
Best overall	KETOTEK KETOTEK KT3100 thermostat plug	13 A / 230 V in the bullets	3 m NTC 10K	No	8.0	about £19.99	View offer
Alternative	KETOTEK KETOTEK KT3200PRO day/night plug	13 A / 230 V	3 m NTC	Yes, M2	7.1	about £22.99	View offer
Preis-Tipp	Nerissa Nerissa T01-UK thermostat socket	16 A and 3680 W claimed	1.7 m NTC 10K	No	6.6	about £15.45	View offer

Best overall

KETOTEK KETOTEK KT3100 thermostat plug

8.0/10about £19.99

View offer

Alternative

KETOTEK KETOTEK KT3200PRO day/night plug

7.1/10about £22.99

View offer

Preis-Tipp

Nerissa Nerissa T01-UK thermostat socket

6.6/10about £15.45

View offer

On this page

1.What a thermostat socket is deciding
2.Load, fuse, and the numbers that clash
3.Probe, memory, and day and night versus timer
4.Which job needs which type

What a thermostat socket is deciding

The plug goes into the wall, the appliance plugs into the thermostat, and a probe on a lead reads the place you care about, which is rarely the skirting beside the socket. If you are shopping for a boiler, a radiator valve, or a wall stat, stop. A plug-in relay does not replace them. On the single-outlet plugs, start below stop is heating and start above stop is cooling. One front socket still means one appliance. A bullet that talks about heating and cooling together, as on the Lotvic page, does not create a second outlet. The only row with two relays is the KETOTEK KT99pro, at £39.99. Leave the button sequence for the how to set a thermostat plug page. If you need the probe and a clock at the same time, most of these plugs will disappoint you, because their timer modes drop the temperature function.

Load, fuse, and the numbers that clash

A normal UK socket is 13 A. BS 1363 plugs and sockets are rated up to 250 V and 13 A, with a BS 1362 fuse in the plug. The socket does not become 16 A because a bullet says so. Sixteen amps at 230 V is the 3,680 W pair on the Nerissa T01-UK and the KETOTEK KT3100BL. Keep the heater inside the lower of the heater’s own rating, the thermostat figure you can reconcile, and 13 A. Thirteen amps at 230 V is 2,990 W. The KT3100 attribute of 68,770 W is not that, so use the 13 A bullet. Electrical Safety First puts a 13 A fuse as the usual match for roughly 700 W to 3,000 W. A 2 kW oil radiator is about 8.7 A. A 3 kW heater sits on the fuse. If the wattage line contradicts the amp line, skip the wattage. The Vaileal bullet writes both 10 A and 3,950 W. Ten amps at about 230 V is nearer 2,300 W, the coherent ceiling on the Inkbird ITC-C216T. Lotvic and the KT2000 raw bullets omit amps entirely.

Testsieger

KETOTEK KETOTEK KT3100 thermostat plug

8.0/10about £19.99

View offer

Probe, memory, and day and night versus timer

Stated probe lengths are 1.7 m on the Nerissa, 2 m on the Vaileal, a 2.79 m control lead on the HIADA, a 2.9 m panel lead plus a 3 m probe on the KT3500, and 3 m on several KETOTEK plugs. A 1.7 m lead can reach a bench on the same wall. It will not cross a greenhouse from a door socket. The Inkbird listing says IP67. A waterproof probe is not a waterproof plug. Memory is not a clock. The KT3500 bullets say the clock may need a reset if power is off for more than two weeks. A Wi-Fi attribute on the KT3200PRO, the Vaileal, and the Nerissa is not an app. F01 to F04 cannot run with temperature control on the KT3100 and the ITC-C216T. On the KT3200PRO, M2 holds two periods with their own temperatures, and M3 is timer only. One frost threshold does not need M2.

Which job needs which type

Entry prices run about £11.99 to £18.00. The middle band is about £20 to £26. The KT99pro is the only row at £39.99. For one heater or cooler, the KT3100 is 4.4 from 508 reviews at £19.99, with 13 A in the bullets and a 3 m probe. The Nerissa is £15.45 and 4.3 from 158. The Inkbird is £25.99, 4.4 from 54, at 10 A and 2,300 W. The Manillefu TC02 is 4.7 from 4 reviews. Four reviews are not a better result than 508. The KT3100BL includes a customer report of fire on a 1,000 W greenhouse heater. For day and night, the KT3200PRO is 4.4 from 65 at £22.99. For two vivarium loads, the KT99pro is 3.3 from 24.

Common questions

Is 16 A on the bullet safer than 13 A?

No. A higher printed current is not a safer plug and it does not raise the wall socket. BS 1363 remains 13 A. The 16 A and 3,680 W pair is the figure to discount, then you size the heater to the lower of the heater rating, a reconciled thermostat rating, and the 13 A fuse. Electrical Safety First’s usual band for that fuse is about 700 W to 3,000 W.

Do I need a 3 m probe or is 1.7 m enough?

You need enough lead to put the probe in the air or on the mat you mean to control, not beside the plug. The Nerissa states 1.7 m, which can be enough on the same wall. A greenhouse run from a door socket often wants the 3 m leads on the KT3100 and the KT3200PRO. Measure the path before you choose on price.

Can one socket run a heater and a cooler together?

Not on the single-outlet rows. Start below stop selects heating, and start above stop selects cooling, one appliance at a time. Two relays in this comparison means the KT99pro only. A brand dual-relay controller such as an Inkbird ITC-308 is a different product and is not one of these twelve rows.

What is the difference between F01 and day and night mode?

F01 to F04 is a timer. On the KT3100 and the ITC-C216T it does not run with the thermostat, so the probe is ignored. Day and night mode, M2 on the KT3200PRO and the KT3500, keeps temperature control and changes the target between two periods. If you wanted both a clock and a probe, check that you are buying M2 and not a cycle timer.

What should I skip if the wattage line contradicts the amp line?

Skip the wattage and do not average the two numbers. The Vaileal’s 10 A and 3,950 W cannot both be the running load. The KT3100’s 68,770 W attribute cannot sit beside a 13 A bullet. Use the amp figure that fits a 13 A socket, or walk away if the page never states amps, as the Lotvic bullets do not.

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