Heatmiser Slimline-E Programmable Thermostat V3 – Intelligent Control for Electric Underfloor Heating
The Heatmiser Slimline-E V3 is a smart, easy-to-use programmable thermostat designed to give you accurate control over electric underfloor heating systems. With a robust 16A switching capacity, flexible programming options and floor sensor control, it is a strong choice for bathrooms, kitchens, conservatories, living areas and other spaces where reliable temperature management matters.
If you are comparing controls, you can also read our Underfloor Heating Thermostats Guide for help choosing the right thermostat for your project. For wider planning, our Underfloor Heating Installation Guide and system selection guide can also help.
Why choose the Heatmiser Slimline-E V3?
This thermostat is built for homeowners and installers who want dependable, programmable control without needing app connectivity. It is ideal where you want straightforward operation, dependable floor temperature sensing and a clean, modern wall-mounted design.
- 16A switching relay suitable for electric underfloor heating loads up to 3,680W
- Flexible programming modes including 5/2 day, 7 day and 24-hour options
- Self-learning Optimum Start to help the room reach temperature when you need it
- Multiple sensing modes including floor sensor only, air plus floor, and remote air plus floor
- Holiday Mode and frost protection for improved energy management
- Large white backlit display with auto-dim function for simple everyday use
- Keylock and temporary hold for added practicality in busy homes
Flexible programming to match your routine
The Slimline-E V3 offers three programming modes, helping you tailor your heating schedule to how you actually use the room:
- 5/2 day programming for weekday and weekend schedules
- 7 day programming for different settings each day
- 24-hour programming for a simple repeated daily routine
This flexibility makes it easier to reduce unnecessary heating time while still keeping floors warm when you need them most.
Optimum Start for smarter comfort
The built-in Optimum Start function learns how quickly your room heats up and calculates when to switch the system on. Instead of heating for a fixed, wasteful period, it aims to reach your chosen temperature at the right time. That means better comfort, less guesswork and potentially lower running costs.
If you are also planning system size and efficiency, our Underfloor Heating Calculator can help you plan your project more accurately.
Floor sensor control for better protection
A 3-metre NTC 10K floor sensor is included in the box. This allows accurate floor temperature monitoring and helps protect sensitive floor finishes from overheating where required. Depending on your setup, the thermostat can be configured in different ways:
- Floor Sensor Only
- Air and Floor Combination
- Remote Air and Floor
This makes the Slimline-E V3 suitable for a wide range of heating mats, loose wire systems and other electric floor heating installations.
Simple design, practical features
The Slimline-E V3 is designed to be easy to live with day to day. The slim profile looks neat on the wall, while the large backlit display keeps settings clear and easy to read. Helpful built-in functions include:
- Holiday Mode for reduced heating while you are away
- Adjustable frost protection during colder periods
- Temporary temperature hold for quick comfort changes
- Keylock facility to prevent accidental adjustments or tampering
Technical specifications
- Switch rating: 16 Amp / 3,680 Watts
- Dimensions: 98mm (H) x 85mm (W) x 13mm (D after installation)
- Mounting: Flush-mounted in a standard 35mm deep back box
- Temperature range: Adjustable from 5°C to 35°C, with up to 45°C selectable
- Sensor supplied: 3-metre NTC 10K floor sensor included
Best for
This thermostat is a strong option for customers who want:
- Reliable programmable control for electric underfloor heating
- A non-Wi-Fi thermostat with simple day-to-day use
- Floor temperature sensing for better comfort and floor protection
- A direct replacement for older Heatmiser Slimline-E models
Helpful related guides
- Underfloor Heating Thermostats Guide
- Electric Underfloor Heating Installation Guide UK
- Choose the Right Electric Underfloor Heating System
- Best Electric Underfloor Heating Systems UK – Buyer Guide
- Underfloor Heating Calculator UK
