Guide · why you need an alarm

Why a coolroom or fridge needs a temperature alarm (and what a good one looks like)

A coolroom that fails at 2am does not ring anyone. By the time someone opens up, the stock has gone and so has your food-safety cover. A temperature alarm exists for exactly that gap: it watches the room when nobody is there and reaches you the moment something goes wrong. This page covers why a coolroom or fridge needs one, and the four things a genuinely good alarm does that a thermometer on the wall never will.

Last reviewed: 21 July 2026

What a failure overnight actually costs

Two hits, not one. First the stock: a full coolroom of meat, dairy or prep is a serious loss, and once it has been through the danger zone you cannot legally sell it or serve it. Second the compliance side: if product went out of temperature and you cannot show when or for how long, you have a food-safety problem, not just a write-off. A compressor does not pick business hours to die.

Why an alarm, not just a thermometer

A dial or a display tells you the temperature when you are standing there looking at it. Nobody is looking at 2am. An alarm's whole job is to reach you when you are not there. That is the difference, and it is the difference between a small loss because you got there in time and a full coolroom in the bin.

What a good coolroom alarm actually does

Four things. If it does not do all four, it is not really an alarm:

  1. Logs temperature continuously. A rolling record, not just a live number, so you can show exactly when something drifted and for how long.
  2. Alerts the moment it goes out of range. The second the temperature climbs past your set point, not an hour later on a schedule.
  3. Alerts on power loss too. A blackout or a tripped circuit is one of the most common ways a coolroom dies overnight. A good alarm treats "no power" as an alarm condition in its own right, because a dead coolroom often still reads a normal temperature for the first hour.
  4. Escalates to a phone. A call or a text to a real person, and a second person if the first does not answer. Not just a buzzer on the plant-room wall that nobody is in the building to hear. Who gets the call, and in what order, is worth setting up before you need it, and that is covered in who gets called when the alarm goes off.

It needs its own power

This is the one people miss. If the alarm runs off the same power as the coolroom, a blackout kills both: the room warms up and the alarm cannot tell you, because it is off too. A good alarm has its own backup power, so a power cut is exactly when it is still awake and calling you.

Sensor types, in plain terms

You do not need a particular brand, you need the right category for your site:

  • Wired probe sensors. A probe in the coolroom hard-wired back to a controller. Solid where you can run the cable.
  • Wireless probe kits. A battery sensor in the room talking to a base unit over radio. Easier to retrofit, no cable runs.
  • LoRaWAN and long-range wireless kits. Low-power radio that reaches across a big site or several rooms from one gateway. Good for a venue with multiple coolrooms and freezers.

Whatever the type, the probe should read the air the food sits in, not the wall, not the door frame, and it is worth checking it against a known-good thermometer now and then.

How this fits food safety

Under Australian food-safety rules, keeping cold food cold and being able to show it is on you as the operator. Continuous logging plus an alarm is how you both prevent the loss and hold the records if you are ever asked. Coolroom record-keeping has its own specifics, set out in coolroom temperature log requirements. For the exact obligations that apply to your business, check the HACCP framework and your state regulator. In NSW that is the NSW Food Authority.

The short version

A coolroom fails on its own schedule, usually overnight, and the cost is stock plus a food-safety breach. A good alarm logs temperature continuously, alerts the instant it goes out of range or loses power, escalates to a real person's phone, and runs on its own backup power so a blackout cannot silence it. Pick the sensor category that suits your site, wired, wireless, or long-range LoRaWAN, not a brand.

Got a coolroom or fridge with no alarm on it? That is the one worth sorting first. Happy to talk through what "out of range or power lost, straight to your phone" looks like for your setup. Tell us about your cold storage and we will map it out.

General guidance only. Confirm your specific food-safety obligations with the HACCP framework and your state food regulator before relying on this.