This document describes an external temperature probe (SES 001) that can be used with various temperature and humidity sensors to sense temperature for heating, hot water, and underfloor heating systems. The SES 001 has a flexible, waterproof casing housing a 5mm diameter probe that extends 20mm from the end of a 3m cable. It has an operating temperature range of -40°C to +125°C and is IP68 rated for water resistance. The SES 001 provides accurate temperature readings to extend the capabilities of comfort control systems.