UFH Installed but Never Commissioned Properly?
“The UFH Was Installed… But Nobody Commissioned It Properly”
Why underfloor heating systems often fail quietly after install — and what commissioning actually means
Introduction — this is where frustration quietly begins
This is one of the most common phrases we hear after a project is finished:
“It works… but it never quite feels right.”
The system is installed.
The floors are down.
The house is lived in.
But:
Rooms heat unevenly
Thermostats are constantly adjusted
Running costs feel higher than expected
Nothing is obviously broken — and that’s exactly why this problem lingers.
What people think commissioning is
Most homeowners assume commissioning means:
Turning the system on
Making sure water flows
Checking nothing leaks
That’s part of it — but it’s not the part that affects comfort.
True commissioning is about:
How the system behaves over time
How different rooms interact
How controls are set for the type of UFH installed
When that step is rushed or skipped, the system may run — but it won’t feel right to live with.
The difference between “installed” and “commissioned”
An underfloor heating system can be:
Perfectly installed
Fully pressure tested
Signed off as complete
…and still perform poorly day to day.
Why?
Because underfloor heating behaves very differently depending on:
Floor construction (screed vs overlay)
Heat source (boiler vs heat pump)
Control strategy and flow temperatures
Commissioning is the stage where all of that is aligned.
What goes wrong when commissioning is skipped or rushed
Pulled from real site experience and real-world complaints, the same issues appear again and again.
1. The system is controlled like radiators
This is one of the biggest mistakes.
Underfloor heating is often left with:
On/off schedules designed for radiators
Aggressive temperature setbacks overnight
Expectations of fast warm-up
For high-mass screed systems, this causes:
Long recovery times
Temperature swings
Occupants constantly overriding controls
The system isn’t faulty — it’s being asked to behave in a way it physically can’t.
2. Flow temperatures are never optimised
Many systems are left running at:
Default factory settings
Conservative temperatures “just in case”
That leads to:
Higher energy use
Reduced efficiency
Less stable comfort
Commissioning is where flow temperatures are:
Matched to heat loss calculations
Balanced across zones
Adjusted once the building is occupied
Skip that, and performance is left on the table.
3. Nobody explains how it should feel
This is the most human failure of all.
Homeowners are rarely told:
How long warm-up should take
Whether constant low heat is normal
How seasonal adjustment works
So when the system behaves differently to radiators, people assume something’s wrong — even when it isn’t.
That uncertainty creates frustration, not comfort.
Why this happens so often
Because commissioning sits in an awkward gap.
It’s not installation
It’s not design
It happens when everyone’s tired and keen to finish
On busy projects, it’s easy for commissioning to become:
“We’ll set it up and move on.”
But this is the stage that determines whether the system feels like a luxury — or a constant annoyance.
How proper commissioning is meant to work
Specialist systems — such as those designed by Nu-Heat — are engineered with commissioning in mind.
Their designs account for:
Room-by-room heat loss
Floor build-ups and coverings
Heat source behaviour
Recommended control strategies
Commissioning is where that design intent is respected and applied on site — not ignored.
How Sable approaches commissioning differently
Sable treats commissioning as part of delivery, not an afterthought.
That means:
Setting controls based on system type (screed vs retrofit)
Balancing flow rates and temperatures properly
Explaining how the system should behave, not just how to change settings
Returning once the system has been lived with, if adjustments are needed
The goal isn’t just “working heating”.
It’s predictable, calm comfort.
A simple test to know if commissioning was done properly
Ask yourself:
Do we understand how long the system should take to respond?
Are we constantly adjusting thermostats to “fix” comfort?
Does the system feel stable — or reactive?
If you’re always chasing comfort, commissioning likely wasn’t finished — it was just started.
Why this matters before blame starts
This pain point is often the precursor to the final one:
“Everyone blamed everyone when it didn’t work.”
Before fingers are pointed at:
Design
Equipment
Installation
Commissioning should be examined — because it’s the step that ties everything together.
Next step — get clarity, not conflict
If your underfloor heating is installed but never quite feels right, the answer isn’t panic.
It’s understanding:
How it was commissioned
How it’s controlled
Whether the settings match the design
Book a system review with Sable Projects to assess commissioning, controls and behaviour before assumptions are made.
Often, small adjustments restore comfort completely.
