Thermostats For Central Heating & Boiler Control
Domestic thermostats come in three main varieties: the room thermostat, immersed capillary thermostat and contact pipe/cylinder thermostat. Honeywell are a well known market leader, but other quality brands include Electro Controls, Cotherm, Drayton, Wolseley and Worcester. Contact us if you’re looking for a specific stat. Capillary Thermostat A capillary thermostat consists of a brass or copper bulb linked to its sensor by a long-coiled metal tube. In domestic central heating systems the bulb contains an expanding/contracting liquid. The sensor closes as the fluid expands or opens as it contracts. Temperature ranges vary, but for example an EC-6 has a 0-100 degree range. A capillary thermostat can be fine-calibrated by turning a nut or spindle. Take care not to kink the capillary tubing or crack the ceramic sensor while handling. Room Thermostat A room thermostat is based on a small diaphragm, which allows for easy installation on to any surface or switchbox. A typical temperature range is 10-30 Centigrade. This type of stat is versatile and can be used to trigger either a heating or cooling system. A heat-anticipator circuit fine-tunes temperature control to avoid hot/cold cycles. Room stats can be tamper-resistant or have a range of controls, LEDS or LCDs. Cylinder Thermostat A cylinder thermostat measures the temperature of a heating pipe or tank by direct contact. The heating system is then controlled either by direct connection to the pump or boiler or by operation of spring return zone valves. The technology is usually based on a bi-metallic strip operating changeover contacts and provides sensitive control. A typical temperature range is 20-90 degrees Centigrade.