Thermostat
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This article discusses some of the many and varied ways in which thermostats are wired into domestic central heating systems.
<cautionary statements about mains voltages etc>
What does a thermostat actually do?
A thermostat is a simply a temperature controlled switch. In its simplest form the switch will default to closed or "On" until the stat reaches a preset temperature. Once it is warm enough, it opens or turns "off".
The temperature at which this happens is usually selected by a user adjustable control.
Do I need one
Cover heating system interlock, TRVs etc.
How many should I have
Discuss cylinder stats, multiple zones, UFH etc.
Types of thermostat
Mechanical Thermostats
diagrams and piccies of trad Honywell style stat
Programmable Thermostats
Wireless Thermostats
Thermostat features
Cover why there are a number of variations and explain things like:
- Anticipator / Compensator heaters
- Changeover contacts
- Frost protection
- Aux switching and contacts
- Optimising stats
What does the thermostat control
- Connecting to a boiler
- Controlling a zone valve
How should I wire it
- Type of cable
- Earthing or lack of
- what to do with spare neutrals
What else can I control with a thermostat
- other apps including switching electric heating loads directly
- cooling loads
- over temperature alarms and sensors.