Cotherm Resource Blog

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Heating, ventilation, air conditioning & plumbing control solutions

Browse Cotherm's Resource Blogs

Heating, ventilation, air conditioning & plumbing control solutions

Why are the Cotherm TSE & TSR thermostat terminals marked A & B?

Why are the Cotherm TSE & TSR thermostat terminals marked A & B?

By Wayne Harrhy • August 20, 2025
On a Cotherm thermostat, the terminals are marked A and B to denote the electrical live input and output, respectively, for a simple switch circuit. Specifically, A is the Live (Brown) connection that receives power, and B is the Neutral (Blue) connection that the thermostat switches.

A Success Story

Cotherm 75 years of experience

The creation of Cotherm!

International expansion : The set up of the UK sales office, which developed into a sales, distribution and assembly site.

1st Electronic controller : This was also a time of expansion with the set up of the Tunisian factory and the USA sales office.

The roll out of the industry leading Smart hybrid control.

Energies saving technologies : Leading the way with Heatpump technologies - Renewable energies.

Digitalisation : loT Connected controllers - Automation - NCF - Heating elements.