The best frost thermostats, compared.
Top pick: TOWER volt-free frost stat Best value: XIEHUZA digital plug-in – Lowest shelf price among plug-in stats that still have a review file and a setpoint near +5 °C, at about £14.99, with a 10 A socket left in view. Updated October 2026.
A frost thermostat turns heating on when the air, or a remote sensor, falls towards freezing. In a UK house that splits into three jobs: a wired volt-free stat for a combi or system boiler in a loft or garage, a plug-in controller for a greenhouse or shed heater, and a wall stat with a low setpoint for electric underfloor heating. A useful one can hold a setpoint near 3–5 °C for boiler frost duty, switch without a very wide gap, and carry a load rating that matches a 230 V circuit. How those jobs differ from a room stat is set out in the [frost thermostat buying guide](/hub/thermostats/frost-thermostat/sub/frost-thermostat-buying-guide). Figures come from the listings and the UK sources named below. In the UK it protects a boiler in a loft, pipe runs in an outbuilding, or tender plants in a greenhouse. It is not a fire alarm, and it only calls for heat when the sensor is cold. Many gas boilers include their own frost protection near 5 °C when the power is left on.
A frost thermostat turns heating on when the air, or a remote sensor, falls towards freezing.
18 products checked · 47 hrs invested · +16,800 readers
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Personal buying guide
Question 1 of 2
How will you connect it?
The TOWER listing B07D4GNW18 is a wired frost stat with volt-free changeover contacts and a diaphragm air sensor, at £15.29 on the 19 October 2026 amazon.co.uk extract, with 4.5 from 13 reviews. Reviewers describe two-wire installs in lofts and garages, including a setpoint around 4 °C after earlier freeze damage. One reviewer calls the switching coarse near the setpoint, and another wanted side cable entry the body does not offer. The extract does not state a control range or a maximum load, so the terminals still have to match your boiler manual. It is the only wired volt-free frost stat kept in this comparison. The short review file is why it is not the top pick, even though the listing wording is the closest match for a loft combi.
Pros
Cons
Best for: A wired volt-free frost call for a combi in an unheated loft or garage, once the boiler terminal map is checked.
Less suitable: A plug-in greenhouse controller, a published 3–10 °C band on the listing, or a large review file.
Specifications
Common questions
What type of device is the T F C Group LLP listing B07D4GNW18?
The listing describes a wired frost stat with volt-free changeover contacts, for a combi boiler frost circuit.
What load limit does B07D4GNW18 list?
The extract does not state a maximum load or a control range. Match the terminals to the boiler manual before you connect it.
The LOWENERGIE TH-926T, listing B0BPJT8WQ3, is a plug-in analogue thermostat at £17.89, with a stated band of +5 to +30 °C, 3,120 W / 13 A resistive, ±2 °C, UKCA marking, and heating and cooling modes. Across 105 amazon.co.uk reviews it sits at 4.4, the largest count in this set. Reviewers use it in sheds, greenhouses and aviaries around 5 °C, often with an oil-filled heater left on maximum so the stat does the switching. Several say the dial reads about 2 °C high against a room thermometer, so the first cold night needs a max/min check. The analogue dial keeps its setting through a power cut, which those reviews prefer to a digital programmer that drops its schedule. The inductive limit on the listing is 460 W, so a fan motor is a tighter cap than a tubular heater. It is the top pick because that review file sits with a 13 A UK plug rating and a setpoint that can hold just above frost.
Pros
Cons
Best for: A plug-in stat for a greenhouse, shed or tubular heater, with a thermometer check on the first cold night.
Less suitable: Volt-free boiler terminals, a setpoint below 5 °C, or day and night schedules.
Specifications
Common questions
What type of device is the LOWENERGIE listing B0BPJT8WQ3?
The listing describes a plug-in analogue thermostat for a greenhouse or shed heater, with a +5 to +30 °C dial.
What load limit does B0BPJT8WQ3 list?
The listing states 3,120 W / 13 A resistive. The inductive limit on the same listing is 460 W.
The XIEHUZA listing B0CSG6PP7N is a plug-in digital thermostat at £14.99, with a stated band of −20 to +120 °C, a 10 A socket, a 2 m waterproof probe, an LCD, and memory after the power goes off. Amazon.co.uk shows 4.2 from 36 reviews. Reviewers mention greenhouses and terrariums; the complaints that repeat are thin instructions and plain packaging. Ten amps is about 2,300 W at 230 V, so a 3 kW fan heater on full load sits over the marked limit. The probe lets you measure plant height rather than the air beside the socket. It is the best value in this set because the price sits under the analogue plug-in while a review file still exists, with that 10 A ceiling left in view.
Pros
Cons
Best for: A lower-priced digital probe controller for a greenhouse or terrarium heater that stays within 10 A.
Less suitable: A 13 A or 3 kW resistive heater, or volt-free wiring on a combi boiler.
Specifications
Common questions
What type of device is the XIEHUZA listing B0CSG6PP7N?
The listing describes a plug-in digital thermostat with a remote probe, for a greenhouse or terrarium.
What load limit does B0CSG6PP7N list?
The listing states a 10 A socket. At 230 V that is about 2,300 W, below the 13 A plug-ins in this set.
The KETOTEK listing B0GQ82T5C8 is a plug-in digital controller at £25.99, with a stated band of −40 to +120 °C, a 13 A / 230 V socket, a 3 m probe, a backlit LCD, and day/night schedules. The amazon.co.uk extract used here has no star rating and no review count, so there is no buyer file to confirm how it behaves in a greenhouse. The wide range and the two schedules help if you set a night hold near +5 °C and a warmer day band. For a single frost setpoint, the extra modes are more to mis-set than a rotary dial. It is the dearest unit in this comparison. Treat the day/night line as a listing feature, not a schedule anyone has reported back on.
Pros
Cons
Best for: A digital plug-in with a remote probe and separate day and night temperatures in a greenhouse.
Less suitable: A buy you want backed by amazon.co.uk reviews, or a simple analogue frost dial.
Specifications
Common questions
What type of device is the KETOTEK listing B0GQ82T5C8?
The listing describes a plug-in digital thermostat with a 3 m probe and day/night schedules claimed, for a greenhouse.
What load limit does B0GQ82T5C8 list?
The listing states a 13 A / 230 V socket. The extract has no amazon.co.uk review count.
The GLOGLOW listing B0CWZ7TWWQ is a wall thermostat for electric underfloor heating at £13.58, rated 16 A / 3,600 W, with a 5 to 40 °C range, a 2.9 m floor sensor cable, and an IP20 marking. The amazon.co.uk extract has no review count. The 5 °C floor of the range can hold an electric heat zone just above freezing, but the switching is mains for a floor mat, not a volt-free combi input. IP20 is an indoor rating, so this is not a stat for a wet greenhouse or an open loft. A Wi-Fi line in marketplace metadata is not matched by an app in the listing bullets, so do not buy it as a smart controller. It is the lowest shelf price in the set and also the least evidenced.
Pros
Cons
Best for: An electric underfloor zone where the lowest temperature you need is 5 °C.
Less suitable: A combi frost terminal, a greenhouse plug-in heater, or a purchase you want backed by reviews.
Specifications
Common questions
What type of device is the GLOGLOW listing B0CWZ7TWWQ?
The listing describes a wall thermostat for electric underfloor heating, with a 5 to 40 °C range.
What load limit does B0CWZ7TWWQ list?
The listing states 16 A / 3,600 W for a floor mat. Switching is mains, not a volt-free boiler frost input. The extract has no review count.
Scores use the five amazon.co.uk listings kept for this comparison, and the review notes already on file. Shelf date 19 October 2026. This is not a lab test. A stated ±2 °C figure, a day/night schedule or a Wi-Fi line is not scored as a measurement. A Drayton RTS3 band of 3–10 °C from a trade page is a reference for the category, not a score for any ASIN here. Weights sum to 100. The highest score is the top pick. The lowest shelf price among plug-in stats that still have an amazon.co.uk review file and a setpoint that can sit near +5 °C is the best value.
Amazon evidence
30%Star rating on amazon.co.uk, then a hard deduction when the count is missing or under a few dozen. A 4.5 from 13 reviews is not scored above a 4.4 from 105. A missing review count is not treated as a hidden five-star file.
Listing fit
40%A control that can hold a frost-relevant setpoint, a stated UK load (a 13 A plug or a marked wired contact), and a sensor you can place in the cold zone. A missing range, a 10 A cap on a plug, or mains underfloor switching sold into a boiler search, scores down.
Review outcome
20%Reviews that describe a loft, garage, greenhouse or shed held near a low setpoint score higher than a file with no texts, or texts that only mention packaging.
Value
10%Shelf price in GBP against a control a UK buyer can use for that job. The lowest price does not score here when the review count is zero. The GLOGLOW price is not scored as best value for a combi loft.
Choose the job before the price. A wired volt-free stat, a plug-in greenhouse controller and a mains underfloor stat are not the same purchase, and a boiler’s own frost mode does not cover every pipe.
A frost thermostat is a temperature control that turns heating on when the air, or a remote sensor, falls towards freezing. In the UK it protects a boiler in a loft, pipe runs in an outbuilding, or tender plants in a greenhouse. It is not a fire alarm, and it only calls for heat when the sensor is cold. Many gas boilers include their own frost protection near 5 °C when the power is left on.
The stat then never sees the loft or the greenhouse. A remote probe belongs in the cold zone, at loft floor level or bench height, not in direct sun. A sensor in the plug body only reads the air around that socket.
A radiator valve or a room stat does not call a boiler frost circuit unless it has a low frost setpoint and a volt-free input. Internal boiler frost protection near 5 °C does not cover every pipe in an unheated space.
A 10 A socket is about 2,300 W at 230 V. A 3 kW fan heater on full load sits over that mark. The LOWENERGIE inductive limit is 460 W, tighter than its 13 A resistive rating. Do not exceed the figure printed for the load you actually connect.
Boiler frost protection needs a wired stat with volt-free or boiler-compatible contacts and a low setpoint band. Dedicated frost models are often quoted around 3–10 °C. The Drayton RTS3 figure on a trade page is that kind of reference. It is not a measured range for the TOWER listing, which does not state a control range or a maximum load. Greenhouse and garage duty usually suits a UK plug-in stat with a probe or an in-plug sensor, a 13 A resistive rating, and a minimum near +5 °C.
Confirm the dial or display can hold the temperature you need. Many greenhouse plugs control from +5 °C. A greenhouse guide puts useful frost setpoints around 2–7 °C, so a dial that stops at +5 °C cannot be set to 2 °C. Coarse mechanical stats may need calibration against a room thermometer. LOWENERGIE reviewers report the dial about 2 °C high. UK mains are 230 V. Plug-in units for resistive heaters should state 13 A or about 3 kW.
Three typical situations, each with a recommendation from this comparison.
You want a wired frost call so the boiler fires before pipes freeze. The TOWER listing is the only volt-free frost stat kept here, at about £15.29, with 4.5 from 13 reviews. The control range and the maximum load are not stated, so the terminals still have to match the boiler manual.
You want a plug-in stat to hold a tubular or oil-filled heater just above frost. The LOWENERGIE TH-926T is the top pick: +5 to +30 °C, 13 A resistive, and 4.4 from 105 reviews. Check the dial against a thermometer on the first cold night, because reviewers report it about 2 °C high.
You want a wall controller whose lowest setpoint is 5 °C for an electric floor mat. The GLOGLOW listing is rated 16 A / 3,600 W with a 2.9 m floor sensor, at about £13.58. It switches mains to the mat. It is not a volt-free input for a combi, and the extract has no review count.
The top pick is the LOWENERGIE TH-926T at about £17.89. It scores 84, the highest here, as a plug-in analogue stat with a +5 to +30 °C dial, 3,120 W / 13 A resistive, UKCA on the listing, and 4.4 from 105 reviews. Reviewers use it in sheds and greenhouses near 5 °C and say the dial reads about 2 °C high. Best value is the XIEHUZA digital plug-in at about £14.99, a different ASIN, with 4.2 from 36 reviews, a 2 m probe and memory after a power cut. Its socket is 10 A, so a 3 kW heater on full load is over the mark. Skip the LOWENERGIE if you need volt-free boiler terminals or a setpoint below 5 °C. Skip the XIEHUZA if the heater needs 13 A.
XIEHUZA digital plug-in
Lowest shelf price among plug-in stats that still have a review file and a setpoint near +5 °C, at about £14.99, with a 10 A socket left in view.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources named below. amazon.co.uk prices, stars and review counts on these five listings were read on 19 October 2026. Page updated October 2026.
This page contains affiliate links to amazon.co.uk (tag pcuk26-21). If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are taken from those listings. We did not run a lab test.
