water underfloor heating background blurred

Manifold S3 Mixing Unit

The Warmup S3 Mixing Unit is added to the manifold whenever local water temperature regulation or hydraulic separation of the primary circuit is required.

Key Benefits


3-Way mixing

The unique mixing unit provides full 3-way mixing control making it compatible with all heat sources


Adjustable bypasses

Featuring integral primary and secondary circuit bypasses, the mixing unit makes commissioning easy without needing to purchase expensive extras


Grundfos UPM3 circulator

When set to operate in its constant pressure mode, this 70kPa circulator makes setting flow meters simple, with flow rates remaining constant whatever the manifold load is

Maintains Temperature for Wet Floor Heating Systems

The heating system’s temperature can be limited to any value between 20°C to 60°C, enabling screeds to be commissioned at 25°C in line with British Standards and set to the most efficient temperature thereafter, with an anti-tamper device ensuring it continues to operate efficiently.

The unique mixing unit is designed to complement all heat sources, not just gas condensing boilers, including heat pumps, biomass and solar thermal. Without the inclusion of the Warmup Mixing Unit overheated water due to sterilisation cycles or peak solar gain could otherwise pass overheated water into the floor causing damage.

The inline isolation valve located above the circulator prevents water bypassing circuits during filling and allows the circulator to be easily replaced when necessary. The Manifold S3 Mixing Unit’s advanced design also minimises both mechanical and hydraulic noise and the nickel plated brass construction is both robust and corrosion resistant, complementing the aesthetics of the Warmup S3 manifold.

You may also be interested in:

Warmup pex-a pipe


Select from a choice of 3 pipe types; PEX-A, PE-RT and PE-RT/AL/PE-RT – tailored to your specific installation and budget.

hydronic underfloor heating control centre

Control Center

All hydronic systems require a control centre that works with the thermostats and heat source, such as a boiler or heat pump.

3ie thermostat


Choosing the correct control system is crucial in ensuring that your heating system works in the most efficient way.

Get A Quote

Get a Free Quote and Order Online Today

Use our online quoting tool to find the best hydro underfloor heating system for your project and purchase it directly from Warmup.

Quoting Tools: instant, accurate, flexible

Warmup offers an extensive range of electric and water floor systems compatible with all floor types, rooms and projects.

Electric Systems

  • ✓ Ideal for zones less than 25m²
  • ✓ Ideal for single rooms
  • ✓ Does not alter floor levels
  • ✓ Great for renovations

Electric Systems Quote
Thumbnail [200x250]


Water Systems

  • ✓ Ideal for larger zones over 25m²
  • ✓ Rapid auto heat loss calculations
  • ✓ Compatible with existing central heating systems
  • ✓ Great for new-builds

Water Systems Quote & Buy
Thumbnail [200x250]
For areas of 24m2 or more, use our full quoting system
Scroll to Top