Thermostat frost protection holiday mode: a low limit

You are at the front door with a suitcase, the January forecast is below freezing, and the heating app is offering Off. That button looks like the way to stop the gas meter while the house is empty. Thermostat frost protection holiday mode is the pair of controls that belongs on the screen instead: a low limit so the system can still call for heat, and dates so that limit ends when you come home. A saved Alexa sentence is a third control, and it needs the broadband you are about to leave behind.

This page is from Peter F., editor for DIY & tools. The figures come from amazon.co.uk listings stored for the Alexa thermostat comparison, from tado’s AI Assist help, and from reviews on those pages. We did not fit a boiler or run a lab test. A stored price can move. A qualifying purchase through our links can earn a commission at no extra cost to you.

In short

Thermostat frost protection is a low limit on the product that states one, and holiday mode is a dated override of the normal week. In this set only the Hive thermostat with Nano 3 hub prints a number, and that number is 7°C on that listing. It is a product bullet, and it does not transfer to a KETOTEK or tado page that never prints it. Alexa cannot keep editing the house from abroad once the link or the batteries have failed.

Frost protection is a low limit, not a comfort setting

Frost protection is the floor under which the control may call for heat while you treat the house as empty. A comfort setting is the temperature you want when someone is in the room. Leaving the floor in place means the boiler can still run if the sensor gets cold. Selecting Off removes that call for the whole trip.

Insurer and home-advice pages often say to leave the heating on low through a freeze. They rarely print the setpoint. Filling that gap with 15°C from memory would be a number these sources do not support. This comparison has one sourced frost figure, and it belongs to one Hive listing.

The figure on the screen is the figure at the sensor. A hallway stat can read 12°C while a kitchen extension on the same system is colder at the outside wall. These listings do not state a temperature at which pipes freeze. Insulation, draughts, and whether the pipe is lagged all change that point.

Frost protection also assumes the heat source can still fire. A boiler that has lost pressure, a frozen condensate drain, an empty oil tank, or a fused spur you switched off will ignore the setpoint. If you smell gas, leave the house and call the gas emergency service for your part of the UK.

What these listings actually state

The Hive thermostat with Nano 3 hub is ASIN B0DCGMD9KX, stored at about £164.99 with 4.4 from 353 reviews. The listing bullet says heating can start if the home drops below 7°C. That is Hive’s figure for that product, not a Building Regulations line, and not a number to paste onto another brand. The kit is heating only, with up to six heating slots a day. The receiver is standard control or OpenTherm where the boiler is compatible.

The KETOTEK bullets gathered for this article name anti-freeze and holiday mode, and they do not print a degree. The stored boiler model is the KETOTEK KTF0155C, ASIN B08FHWJY7L, at about £44.99 with 4.1 from 840 reviews. Its schedule line is six periods, on a 5-2, 6-1, or 7-day pattern, with holiday mode named. Anti-freeze without a number means you cannot tell a neighbour the house holds 7°C by pointing at Hive.

The two-wire Beok, ASIN B0FHW6PTPM, is stored at about £42.99 with 4.0 from 90 reviews, and there is no frost degree to quote. Reviewers describe battery life from about a week to about six weeks, and one review says the heating defaults to on when the batteries run out. A USB-C lead is the listing’s alternative to cells. That line is a review, not a specification. If the wall has only two wires, the Alexa thermostat buying guide sets that cable beside the other listings.

Those products sit on the Alexa thermostat comparison. The top pick there is the tado V3+ wireless starter kit, ASIN B08LP1LS5T, stored at about £57.50, with 4.5 from 307 reviews. That shelf figure is not a frost setpoint, and tado’s holiday note does not hand you Hive’s 7°C. A live amazon.co.uk basket can differ.

Holiday mode and the OpenTherm caveat

Holiday mode is a pair of dates. For that window the control should follow the away behaviour instead of weekday slots that still heat an empty kitchen at 06:30. If the app only offers a date, treat the mode as ending at the start of the day you come home. A weekly schedule with no holiday override will still run while you are away.

tado’s AI Assist help describes holiday mode with those dates. On an OpenTherm connection, the same article says the boiler may move to its lowest hot-water setting rather than switch fully off. We did not run the boiler, and that sentence is not a reason to type 7°C into a tado account. If your tado is on a plain relay, this OpenTherm line does not describe that relay.

Being away when the link or the batteries fail

Alexa is a path to the setpoint. It is not the setpoint. If the router is unplugged, the hub is offline, or the skill cannot see the stat, a sentence from a hotel does not reach the receiver. The Alexa thermostat setup guide spells out that offline limit. Use the frost mode on the heating product itself. A routine is a spare switch for when you are at home.

Unplugging the router removes the only view you have from abroad. Save the holiday dates, watch the receiver or the boiler, then close the app. A green tick confirms the phone. It does not confirm the heat source.

On the two-wire Beok, stored reviews put life at about a week on some cells and about six weeks on others. One reviewer says a flat pack leaves the heating calling. Fit new cells, or connect the USB-C lead, before a trip longer than the short end of that range. The range is those reviews, on 90 reviews at 4.0 stars, not a lab drain test.

Smart Life and Tuya keep holiday dates on the account that owns the stat. If the landlord cannot open that login, nobody can end the holiday or raise the floor. Add them before you delete the email. A Hive or tado account has the same limit if you are the only admin.

A short leaving checklist

Do this on the evening before you travel, while you can still see the boiler. The list is for a winter absence, whether that absence is a weekend or two weeks. A summer weekend can skip it.

1. Read the frost line on your own listing, and keep Hive’s 7°C on the Hive listing that printed it.
2. Enter holiday dates for every night away, and end them so the normal schedule can heat the house before you walk in.
3. Leave a low limit on for a winter trip, and leave Off unselected.
4. On a two-wire battery stat, fit fresh cells or the USB-C lead.
5. Leave the router and the hub powered, and confirm the receiver after the app is closed.
6. Keep Alexa routines out of the frost job, because a hotel network is not guaranteed.
7. If you rent, put Smart Life or Tuya on an account the person who stays responsible can open.
8. Check the boiler pressure against the range in that boiler’s manual.
9. If you smell gas, or the case has to come off, stop. Call the gas emergency service or a Gas Safe registered engineer.

The low limit is there for a few cold days. Off leaves a house that cannot call for heat until someone is home. If the listing never named frost, holiday, or anti-freeze, the Alexa thermostat comparison sets out the stored boxes before you invent a mode the hardware does not have.