️ Summary Report: Kee/NuHeat Underfloor Heating (UFH) Systems – Common Issues & Longevity Strategies
Background
Many homes installed Kee/NuHeat underfloor heating systems between the early 1990s and early 2000s. These systems often used Santoprene
triple-layer "Contraflow" tubing, typically red or black in colour. Over time, users have reported system degradation, particularly
pipe cracking,
manifold leaks, and
component failure.
Common Problems Identified
1. Pipe Deterioration
Black and red triple-layer pipes can become brittle and crack over time, especially at
stress points near manifold connectors.
Cracking often occurs due to:
Leaching of plasticisers
Hoop stress at fittings
Heat cycling and high operating temperatures
2. Leaks
Most failures are near
copper manifolds or
pipe joins, sometimes through ceilings.
Leaks can appear even when the heating system is off.
Some homeowners report
multiple leaks over a short period as the system nears end-of-life.
3. Manifold & Pump Issues
Bronze pumps were originally required; however, if the system is isolated,
steel pumps can be used.
Solenoid valves and actuators commonly fail after years of use.
Temperature control and thermostats may fail or provide incorrect readings.
4. Scaling and Flow Problems
Systems using
thermal stores often suffer from
limescale buildup in coils, reducing hot water temperature.
This can also confuse thermostats and affect pump operation.
Maintenance & Life-Extension Tips
✔ Reduce Operating Temperature & Pressure
Lowering flow temperature and system pressure
reduces stress on aging pipes.
Aim to run the system at
the minimum temperature and pressure needed for comfort.
✔ Minimize Mechanical Stress
Ensure
pipes are not pulled, bent, or under tension near manifolds.
Avoid placing items or building materials near exposed pipes.
✔ Replace Actuators & Upgrade Manifolds
Replace
thermal actuators or solenoids that no longer open properly.
Retrofitting new manifolds is often possible and can greatly extend system usability.
✔ Consider Using Leak Sealer
Products like
Fernox Leak Sealer F4 can be added as a temporary fix for
minor weeping leaks.
It circulates in the system and seals leaks when it contacts air.
✔ Isolate & Pressure-Test Each Zone
A thorough
pressure test of each UFH zone can identify hidden weaknesses.
If pipe loops in the floor are intact, they can be retained while
new pipe sections and
manifolds are added above floor level.
✔ Isolate UFH from Radiators
Some systems use a
stainless steel heat exchanger to isolate UFH from the main heating circuit, avoiding inhibitor damage to pipes.
✔ Use Kick-Space Heaters in Unserviceable Areas
If radiators are hard to install (e.g., in a kitchen),
fan-assisted plinth heaters from Smith’s Industries are a discreet solution.
When to Replace the System
You should consider full system replacement if:
Leaks are occurring
in multiple, hard-to-reach areas
Pipe degradation is widespread
Replacement parts are
no longer available or cost-effective
You're planning
major renovations anyway
Replacement options include:
Standard radiators
Dry or wet UFH with modern plastic (e.g., PEX) pipe
Ducted warm air systems like ComfortDisc (if minimal disruption is a goal)
Final Notes
No formal recall or compensation seems to have been available from NuHeat.
Several users expressed frustration with lack of support.
A knowledgeable heating engineer is essential for evaluating your specific situation.
Look for an engineer with
experience in retrofitting or phasing out Kee/NuHeat systems.
