Heat alarms are a specific and often misunderstood part of a residential fire detection system. Unlike smoke alarms, they don’t detect particles in the air — they detect temperature changes. Understanding how they work, and where they’re designed to go, helps homeowners build a more complete fire safety setup.

 

The Mechanics of Heat Detection

Most residential heat alarms use one or both of two detection methods:

 

Fixed temperature detection triggers the alarm when the ambient temperature inside the unit reaches a specified threshold. For most residential models, this is around 58°C — a temperature that normal room conditions, including cooking, would not typically reach.

 

Rate-of-rise detection monitors the speed at which temperature is increasing. If the temperature rises by more than a set amount within a short period, the alarm triggers regardless of the absolute temperature. This allows the alarm to respond to rapidly developing fires before the temperature has reached the fixed threshold.

 

Better quality heat alarms combine both methods, providing response across a wider range of fire scenarios.

 

Why Wireless Matters

The key advantage of wireless heat alarms is their ability to communicate with other alarms in the home without needing a physical cable connection. When a heat alarm in the kitchen activates, all connected smoke alarms throughout the house sound simultaneously.

 

This interconnection transforms a heat alarm from a localised warning device into part of a whole-home fire detection network. Occupants in bedrooms at the other end of the house receive the same warning as if the fire were directly outside their door.

 

Wireless systems use radio frequency communication, typically operating at 868MHz or 433MHz. Reputable systems conduct regular polling between units to confirm each alarm remains in contact with the network.

 

Where Heat Alarms Should Be Installed

Heat alarms are designed for specific environments where smoke alarms would generate unacceptable numbers of nuisance activations. The primary locations are:

 

Kitchens — cooking produces combustion particles, steam, and airborne oils that trigger smoke alarms. Heat alarms are immune to these.

 

Garages — vehicle exhaust, solvents, and petrol fumes create an environment unsuitable for smoke detection. Heat alarms provide reliable coverage here.

 

Utility areas — boiler cupboards, laundry rooms, or workshop spaces where dust, steam, or fumes are regularly present.

 

Where Heat Alarms Should Not Be Used

Heat alarms are not substitutes for smoke alarms in bedrooms, hallways, living rooms, or stairwells. Their response is inherently slower than smoke detection because they require a fire to produce significant heat before triggering. In the areas where early warning is most critical — sleeping spaces — a photoelectric smoke alarm is always the right choice.

 

Installation Guidelines

Heat alarms should be mounted on the ceiling, away from air vents, extractor fans, and direct draughts that might slow temperature rise detection. In kitchens, the optimal position is between the cooking area and the door — not directly above the hob, where concentrated cooking heat can cause false activations.

 

Follow the manufacturer’s guidance on minimum distances from cooking appliances. Most recommend at least one metre from a hob or oven.

 

Pairing With Smoke Alarms

A heat alarm installed in isolation provides useful local coverage but misses the benefit of interconnection. When paired with a network of smoke alarms using the same wireless protocol, the full alarm network activates when any unit triggers. This is the configuration recommended under NZS 4514 for residential fire detection in New Zealand.

 

Before purchasing, confirm that your chosen heat alarm is compatible with the smoke alarms already installed or planned for the rest of the home.