If your underfloor heating (UFH) needs attention—whether it’s a leak, a cold spot, or a faulty connection—one of the first questions people ask is: do I need to turn it off for the repair to go ahead? The answer depends on the type of system you have, the nature of the fault, and the work being carried out. In most cases, yes—it must be turned off, but there are a few exceptions.

Here’s a practical breakdown to help you understand what’s required and why.

Wet (Hydronic) Underfloor Heating: Turning It Off Is Essential

Water-based UFH systems almost always need to be shut down before inspection or repair. Leaving the system active puts your pipework, screed, flooring and the engineer at risk.

Reasons to switch off a wet UFH system:

• Pressure needs to be isolated to locate leaks safely
  
• Water flow must be stopped before pipework is opened or cut
  
• Temperature checks are more accurate when the system is cooled
  
• Manifold work requires isolation of loops and heat sources
  
• Boilers and pumps may need to be powered down
  

Even if only one zone is affected, the system will typically need to be depressurised or isolated at the manifold.

Electric Underfloor Heating: Power-Off for Safety

Electric UFH doesn’t involve water, but it still poses electrical and fire risks if it’s left on during repair or inspection.

Always turn off electric UFH when:

• A fault, hot spot or dead zone is being investigated
  
• Flooring needs to be lifted
  
• A cable repair or thermostat check is required
  
• Moisture is suspected under the floor
  
• Electrical components need testing
  

Repairs may involve resistance checks or circuit testing, so the system must be disconnected from the mains first.

Can Underfloor Heating Be Switched Off Just in One Area?

Sometimes, but it depends on the installation.

Wet systems

Manifolds often allow individual loops or zones to be isolated. This means an engineer may only turn off the affected circuit rather than the entire heating system—but it still counts as shutting the relevant section down.

Electric systems

If the UFH is wired in separate zones with independent thermostats, only the affected circuit needs isolating. Larger single-zone systems usually require a full shutdown.

What If You Don’t Turn It Off?

Continuing to run a faulty or leaking system can make matters worse.

Risks include:

• Flood damage to screed, joists and insulation
  
• Further pipe failure due to pressure
  
• Boiler lockouts caused by pressure loss
  
• Overheating of electrical cables
  
• Higher repair costs if the issue spreads
  
• Flooring damage from trapped heat or moisture
  

Ignoring a leak or wiring fault can turn a simple fix into a major job involving floor removal.

How Long Does It Need to Stay Off?

Timeframes vary depending on the issue:

• Diagnostics only – as little as 30 minutes, depending on access
  
• Small pipe repair – often a few hours
  
• Manifold or connection work – several hours or more
  
• Full leak trace – half a day or longer
  
• Electric cable repair – depends on access and flooring type
  

You don’t need to worry about scheduling—you simply need the system off before the expert arrives.

Will Turning It Off Affect the Rest of the Heating?

Not necessarily.

For wet systems:

• If UFH is separate from radiators, only the affected zone may be shut off.
  
• Combination boilers sometimes need to be turned off if pressure is lost—but only temporarily.
  
• In many homes, heating engineers can shut off and isolate UFH loops while leaving the rest of the system active.
  

For electric systems:

• Only the zone on the faulty circuit needs to be switched off in most cases.

Do You Need to Turn It Off Before the Engineer Arrives?

In most situations, yes—it helps with diagnosis and ensures the floor is cool enough to access or scan.

Best practice:

• Switch the affected UFH zone off the night before.
  
• If unsure which loop or circuit is involved, turn off the entire system.
  
• For wet systems, don’t top up pressure if it’s dropping—leave it for the engineer to assess.
  

If in doubt, switching off the heating at the thermostat or manifold is a safe starting point.

Can Repairs Be Done Without Lifting the Floor?

Some fault-finding and diagnostics can be carried out without floor removal, but this doesn’t change the need for the system to be off.

Tools used without floor removal:

• Thermal imaging cameras
  
• Acoustic leak detection
  
• Electrical resistance testing
  
• Flow and pressure checks
  

But once a repair area is identified, power or water must be shut off for safe access.

Final Word

Yes—underfloor heating should always be turned off before repair work begins. Whether it’s a wet or electric system, switching it off protects your property, reduces the risk of further damage, and allows the engineer to work safely and accurately.