Design and labels
The manifold, loops and zone labels match the approved design and as-installed layout.
Professional commissioning guide
How Do I Commission a Water Underfloor Heating System?
Commissioning proves that the system is filled, purged, leak-free, responding to its controls and delivering the design flow through every circuit.
It is more than connecting a hose to the manifold. Use the project design, current product instructions and heat-source requirements.
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Competent-person work
Commissioning should be completed by a competent heating professional using the Uheat design, current product instructions and heat-source requirements. Electrical wiring and testing must be completed by a suitably qualified electrician.
Before commissioning begins
Confirm the installation is ready to test as a complete system
Pressure records
Required pressure tests were completed and recorded at the correct installation stages.
Cured floor layers
Screed, levellers, adhesives and finishes have cured or dried for the specified period.
Compatible equipment
The heat source, mixing control, pump, wiring centre, thermostats and actuators are installed.
Electrical checks
Protective devices and control wiring have been tested by the responsible electrician.
Design settings
Flow rates, circuit schedule and permitted temperature settings are available at the manifold.
Seven stages
Commissioning sequence
Work in order and record each result rather than adjusting the system by feel.
- 1Inspect and identify
Check manifold orientation, valves, fill and drain points, vents, pump or mixing assembly, actuators and labels. Record approved site changes.
- 2Fill and purge each circuit
Use the separate filling guide. Purge one circuit at a time until water runs without visible air, then restore the correct valve positions.
- 3Confirm pressure and leak integrity
Set the cold pressure required by the design and heat-source instructions, inspect accessible joints and record the stable result.
- 4Prove controls and interlock
Call for heat from each thermostat. Confirm the right actuator, pump and heat-source demand operate, then close correctly when demand ends.
- 5Set water temperature and pump
Configure the heat source, mixing arrangement and pump to the design values. Confirm flow direction and investigate persistent air noise.
- 6Balance the circuits
With the relevant zones open, adjust every flowmeter to its design rate. Recheck all loops after changes and record final flow.
- 7Complete the controlled first heat-up
Follow the screed and finish start-up schedule, raise temperature gradually where instructed and prove every zone through a normal cycle.
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Do not use underfloor heating to force-dry the floor
Starting too early or raising temperature too quickly can damage screed, adhesives or finishes. Cure, moisture and first-heat requirements come from the relevant material manufacturers.
Commissioning record
What to record
The handover should show what was designed, tested, set and changed.
| Record | Minimum information |
|---|---|
| Project and system | Address or area, heat source, manifold ID, commissioning date and responsible person. |
| Circuit schedule | Zone or room, loop number, design flow, final measured flow and actuator channel. |
| Temperatures | Relevant flow, return, mixing and configured maximum values after stable operation. |
| Pressure | Cold fill pressure, available test information and final stable operating pressure. |
| Controls | Thermostat names, sensor or limit settings, schedules, wiring-centre outputs and interlock result. |
| Pump and mixing | Pump mode, mixing setting and any design-specific differential or bypass setting. |
| Floor start-up | Cure confirmation, start date, staged temperatures and observations. |
| Exceptions | Approved changes, unresolved defects, restricted zones and actions before handover. |
Project and system
Area, heat source, manifold ID, date and responsible person.
Circuit schedule
Zone, loop, design and final flow, and actuator channel.
Temperatures
Flow, return, mixing and maximum values after stable operation.
Pressure
Cold fill, prior test information and stable operating pressure.
Controls
Thermostats, sensors, limits, schedules, outputs and interlock.
Pump and mixing
Pump mode, mixing control and design-specific settings.
Floor start-up
Cure confirmation, start date, staged temperatures and observations.
Exceptions
Approved changes, defects, restricted zones and remaining actions.
Owner handover
Leave a record that can be used after the installer leaves
- As-built pipe layout and photographs taken before covering
- Pressure-test and electrical test records and certificates
- Manifold schedule, design flows and final settings
- Heat-source, pump, mixing and control instructions
- Approved floor-temperature limits and first heat-up record
- Normal operation, seasonal start-up and fault contacts
After commissioning
Change one setting at a time
Let the controls operate normally and avoid several large changes together. Water underfloor heating can respond more slowly than radiators, especially in thick screed.
If a room does not reach temperature, check demand, actuator operation, flow and design conditions systematically rather than increasing every flowmeter or temperature.
Commissioning questions
Frequently Asked Questions
Answers about filling, flow rates, temperature, zero readings and handover.
Is filling the manifold the same as commissioning?
No. Filling and purging remove air and establish the water charge. Commissioning also proves pressure integrity, controls, heat-source demand, pump and mixing operation, balancing, first heat-up and handover records.
What flow rate should each loop have?
Use the design flow stated on the circuit schedule. A single generic flow rate is not appropriate because circuit lengths and room loads differ.
What temperature should I set?
Use the designed water temperature and the limits for the screed and floor finish. Do not copy a setting from another project.
Why is one flowmeter reading zero?
Possible causes include a closed valve or actuator, trapped air, incorrect pump operation, contamination or a control issue. Work through the system methodically and use a competent professional if the cause is unclear.
What should the homeowner receive?
At minimum: layouts, test and commissioning records, circuit schedule, final settings, relevant certificates, product manuals and operating guidance.