A heat sensing module for a heat alarm apparatus comprises a base section having a concave surface, a cage, a heat sensor, and a control circuit configured to detect a temperature rise at the heat sensor and output an alarm signal in response thereto. A sensing part of the heat sensor is located in a space formed between the concave surface of the base section and the cage. The concave surface assists with reflecting, radiating and absorbing heat to increase the speed at which the heat sensor registers a change in temperature.