Water underfloor heating installation
Water Underfloor Heating Installation Guide
Follow the complete process, from planning the controls and positioning the manifold to pressure testing and commissioning.
Work through the six stages online, or download the illustrated manual for detailed diagrams, floor build-ups and installation records.
Step-by-step installation guide
Install Your Water Underfloor Heating System
Follow the six stages in order for a smoother, more reliable installation. Expand each section for practical instructions, essential checks and the relevant pages from the full Uheat manual.
1 Step 1 Plan the Wiring and Controls
Set out the controls before commissioning begins. A clear room-by-room plan helps ensure every thermostat operates the correct circuit and all electrical work can be checked safely.
- Confirm the zone plan, thermostat positions and heat-source controls for every room.
- Position the wiring centre close to the manifold, with clear access for installation and servicing.
- Connect the thermostats, actuators, pump and heat-source demand using the diagrams supplied with the controls.
- Keep the electrical supply isolated until the wiring has been checked and the hydraulic system is ready.
Electrical safety: Wiring arrangements vary between control systems. Always use the diagram supplied with the controls on site, and have the final connections completed and tested by a qualified electrician.
Wiring and thermostat diagrams
2 Step 2 Position the Manifold and Pump
Choose the manifold position before laying any pipe. A central, accessible location keeps circuit runs practical and makes filling, balancing and future servicing easier.
- Use the system design to choose a central position close to the rooms it will serve.
- Allow enough space for the pump, mixing controls, actuators, wiring centre and pipe connections.
- Mount the complete assembly level and securely to the wall.
- Label each flow and return connection by room before pipe installation begins.
Confirm the position against the project design before fixing it. Moving the manifold later can add unnecessary pipe length and make the system harder to balance.
Manifold connection guide
3 Step 3 Lay the Underfloor Heating Pipework
Follow the supplied room-by-room layout and use the fixing method specified for your floor system. Keep every circuit continuous, clearly labelled and protected throughout the installation.
- Connect the first pipe end to the manifold before laying the loop.
- Run the pipe to the coldest part of the room first, then follow the designed pattern and spacing.
- Secure the pipe using the fixing method specified for the floor system.
- Keep bends smooth, avoid kinks and do not create buried joints.
- Return the second pipe end to the correct manifold connection and label both tails.
Pipe spacing must follow the system design. The layouts in the manual are typical examples; the correct spacing depends on room heat loss, water temperature, floor finish and required output.
Typical pipe layouts
4 Step 4 Connect the Pipework and Fill Each Circuit
Make each manifold connection carefully, then fill and vent one loop at a time until the water runs steadily and no trapped air remains.
- Cut each pipe square and use the correct calibrating or re-rounding tool.
- Fit the nut, olive and pipe insert, then connect the flow ends before the returns.
- Close the primary isolating valves so fill water cannot enter the heat source.
- Connect the mains-water hose to the fill valve and a drain hose to a suitable outlet.
- Open and flush one circuit at a time until the water runs free of air, then close it and repeat for every loop.
Do not fill the underfloor circuits through the boiler or heat pump. Fill from the manifold as described in the manual, with the primary side isolated.
Filling and testing sequence
5 Step 5 Pressure-Test the System Before Covering
Test every circuit while the pipework and connections are still visible. This is the best opportunity to find and correct any damage or leaks before the floor build-up conceals the system.
- Open the underfloor circuits and keep the primary system isolated.
- Use a suitable hydraulic pressure-testing pump and follow the supplied test schedule.
- Check every manifold connection, valve and visible pipe route for leaks.
- Record the result on the pressure-test certificate and photograph the gauge and installed pipework.
- Maintain the pressure specified for the floor-installation stage while screed or covering work is completed.
Do not use compressed air for routine hydraulic testing unless the project method statement specifically permits it. Never cover an untested system.
Pressure-test certificate
6 Step 6 Start, Balance and Commission the System
Once the floor has fully cured and the heat source, controls and pipework are ready, bring the system into service gradually and check every room independently.
- Set each thermostat to call for heat and allow time for its actuator to open.
- Confirm that the correct room loop responds to each thermostat.
- Balance the manifold flow rates to the room-by-room design, then check the system when all zones are operating.
- Set the mixing controls and heat source to the designed water temperature.
- Raise the floor temperature gradually in accordance with the screed, adhesive, floor-finish and system manufacturers’ instructions.
Do not use underfloor heating to force-dry a new screed. Final hydraulic, electrical and heat-source commissioning should be completed by competent trades, with settings recorded for the customer.
Start-up and balancing guide
Keep the Full Guide with Your Project
The PDF includes the complete wiring schematics, floor build-ups and pressure-test certificate for your installation records.
Water installation advice
Installation Questions, Answered
Quick guidance on DIY installation, manifolds, pressure testing and heat pumps.
Can I install water underfloor heating myself?
A capable installer can complete some physical stages using a supplied design and instructions. Professional input is still needed for heat-loss design, heat-source and electrical connections, balancing and commissioning.
Do I need a manifold?
A multi-circuit water system normally uses a manifold to distribute water, isolate and balance each circuit, and support room or zone control. Its size must match the designed circuit count.
Should the system be tested before screeding?
Yes. Fill and pressure-test the pipework to the supplied instructions before concealment. Record the test and photograph the layout.
Can water underfloor heating work with a heat pump?
Yes. It can suit lower water temperatures when room heat loss, floor output, flow rates and controls have been designed together.