Underfloor Heating Not Working: Problems, Fixes & What to Do

James Elston
Written by James Elston
Updated on 27th January 2024
Posted on 11th January 2024
Topic: Boiler Advice
underfloor heating not working

Is your underfloor heating not working? You’re likely searching for a solution that’s both quick and reliable.

Our guide dives straight into pinpointing common issues and providing clear, actionable solutions to get your underfloor heating system up and running swiftly.

Expect practical advice that addresses the problems you’re facing without any fluff.

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Underfloor Heating Problems Overview

  • Regular maintenance, including annual servicing and early detection of problems, can extend the life and efficiency of an underfloor heating system.
  • Common issues such as uneven heat distribution, continuous pump operation, and low pressure can often be resolved through troubleshooting methods like bleeding air from the system, cleaning debris from pipes, and maintaining correct pressure levels.
  • Professional assistance may be required for complex issues like leak detection, electrical faults, or system flushing to ensure safe and effective repair and maintenance of your underfloor heating system.

Identifying Underfloor Heating Issues and Causes

Understanding your underfloor heating system is the first step towards effective problem-solving.

The most common underfloor heating problems, including wet underfloor heating problems, involve uneven heat distribution, constant pump operation, and low pressure.

Each of these issues has distinct symptoms and causes, and knowing how to identify them is half the battle won.

Next, we will explore each problem and discuss potential solutions.

Uneven Heat Distribution

Ever noticed certain areas in your room feeling colder than the rest? This could be due to uneven heat distribution in your underfloor heating system.

Similar to when a radiator is hot at the top but cold at the bottom, the main culprits are trapped air, debris, or an incorrect setup.

Ensuring your pipes are clean and free of debris during the installation process can help maintain a clear pathway for heat distribution.

Moreover, keeping an eye on the blending valve pin for any obstructions can help prevent uneven heat distribution.

Constant Pump Operation

If your pump runs continuously, it could be due to:

  • High pressure
  • Air in the system
  • Blockage in the system
  • Diaphragm damage

It’s important to reduce high pressure, which can be dangerous, by closing the valves at both ends of the filling loop, thus preventing the system from losing pressure.

If you suspect a blockage, bleeding the system might help. If all else fails, consult a heating engineer to prevent further damage to your underfloor heating system.

Low Pressure

Low pressure can significantly affect your underfloor heating system’s performance. Leaks in the layout or valve issues can cause this drop. In fact, actuator problems can lead to a significant pressure drop due to associated leaks.

If you use a boiler to as the heat source, check the boiler for low pressure and top it up.

Therefore, resolving low-pressure issues involves locating leaks and rectifying valve and actuator problems, plus topping the pressure back up.

Read more: What is the cost of underfloor heating

Dealing with Single Zone Heating Problems

While some problems affect the entire underfloor heating system, some only affect a single zone. The thermostat, actuator, and pipes play the most important roles here.

Understanding common single zone heating problems and their solutions can help you maintain a comfortable temperature throughout your home.

We will now dissect these issues individually.

Thermostat Troubleshooting

The thermostat is like the brain of your underfloor heating system. It controls the heating system’s operation, so any issue with it can cause heating problems.

If your underfloor heating isn’t working in one zone, a faulty thermostat or a low battery could be to blame.

Regularly checking the power supply, settings, and functionality can help you address thermostat-related issues promptly.

Actuator Issues

An actuator regulates the opening and closing of the valve on the manifold, adjusting the fluid flow according to signals from the zone thermostat. If an actuator is defective, it can cause continuous heating in a zone. Regular actuator inspections and replacement underfloor heating, when necessary, can mitigate this problem.

Trapped Air in Pipes

Trapped air in the pipes can cause uneven heating in a zone. By listening for unusual noises and checking the air bleed valves, you can identify trapped air. Bleeding the system to let the air escape, and then refilling the system to restore proper pressure, can help resolve this issue.

Addressing Multiple Zones or Entire System Malfunctions

When issues affect multiple zones or the entire system, it can be quite challenging. From circulation pump failure to wiring board issues and isolation valve closure, these problems require a more comprehensive approach.

We will now dissect these issues in detail and discuss their solutions.

Circulation Pump Failure

By circulating hot water from the heat source throughout the underfloor pipes, the circulation pump is a vital component of your underfloor heating system. If this heating pump fails, it can cause multiple zones or the entire system to not heat.

So, if you notice a noisy heating pump in operation, reduced hot water pressure, or the motor not starting, you might be dealing with a pump failure. In such cases, a professional should be called to diagnose and repair the issue.

Wiring Board Issues

Wiring board issues can lead to significant malfunctions in your underfloor heating system. These issues can be as simple as a pump relay stuck on the wiring board or as complex as a faulty thermostat or underfloor heating actuator problems.

In case of wiring board issues, make sure the main isolating switch supply is active.

If the issue persists, consult an electrician to inspect the wiring board connections and relays.

Isolation Valve Closure

Isolation valves regulate water flow to different components of your underfloor heating system. If these valves are stuck or mistakenly left in the closed position, it can hinder proper water flow, leading to cold zones or complete system shutdown.

Thus, regularly inspecting these valves and making sure they remain open can prevent such problems.

Flooring Compatibility and Impact on Underfloor Heating

The flooring material you choose for your home has a direct impact on the efficiency of your underfloor heating system. Certain materials conduct heat better than others, while some materials can hinder heat transfer.

We will now examine the factors surrounding flooring material, its thermal conductivity, and the implications of floor covering thickness on the system.

Flooring Material Considerations

Flooring materials like ceramic and stone tiles are great conductors of heat, making them ideal for underfloor heating systems.

On the other hand, certain materials like thick carpets and high tog underlays can hinder heat transfer, making them less suitable for such systems.

Thus, selecting appropriate flooring material can have a considerable impact on the efficiency of your underfloor heating system.

Thermal Conductivity

The thermal conductivity of your flooring material is a critical factor in determining how efficiently your underfloor heating system works.

Materials like stone and ceramic have high thermal conductivity and good heat retention, enhancing the efficiency of underfloor heating systems.

On the contrary, materials with low thermal conductivity can lead to inefficient heat transfer and uneven heating.

Floor Covering Thickness

The thickness of your floor covering can directly impact the efficiency of heat transfer and heat output from your underfloor heating system. For the heating system to work effectively, your floor covering should not exceed a combined TOG value of 2.5.

Materials with high TOG values, like thick carpets and underlays, may not be suitable for underfloor heating systems, as they may hinder heat transfer.

Maintaining Your Underfloor Heating System

Regular maintenance can help extend the lifespan of your underfloor heating system and keep it working at its best. Ensuring the efficiency and durability of your underfloor heating system can be achieved by implementing basic preventative steps, arranging annual servicing, and early detection of problems.

Preventative Measures

Preventative measures such as insulating the pipes and correctly setting the controls can go a long way in maintaining your underfloor heating system. Moreover, choosing compatible flooring materials can also prevent common issues, ensuring your system operates at its best.

Annual Servicing

Much like your car, your underfloor heating system also benefits from regular servicing. Annual servicing involves a thorough inspection of the system’s components such as the position and operation of the valves and manifolds. It can help identify and fix potential issues, thereby preventing costly repairs down the line.

Early Detection of Issues

Catching an issue early can prevent it from escalating into a larger, more expensive problem. Regular checks can help identify unusual noises, temperature fluctuations, and other signs of potential issues.

By addressing these problems promptly, you can ensure the longevity and efficiency of your wet underfloor heating systems and other underfloor heating system types.

Pressure-Related Concerns and Solutions

Pressure-related issues are common in underfloor heating systems. From the pressure relief valve to the filling loop and the expansion vessel, each component plays a pivotal role in maintaining the system’s pressure.

We will now explore these concerns and their possible solutions in depth.

Pressure Relief Valve Maintenance

By regulating water flow and maintaining system control, the pressure relief valve is a vital component of your underfloor heating system. Regular maintenance of this valve can prevent pressure-related issues.

This involves conducting a valve test every 12 months and considering repairing or replacing a pressure release valve every three to five years.

Filling Loop Inspection

The boiler filling loop connects your underfloor heating system to the water supply for filling and pressurising the system. Regular inspection of this loop can help identify potential leaks or valve issues, which can cause low pressure in the system.

Read more about filling loops here

Expansion Vessel Replacement

The expansion vessel regulates the expansion and pressure changes as the system undergoes heating and cooling.

If this vessel is damaged or not functioning correctly, it may be necessary to replace it to prevent pressure-related issues in your underfloor heating system.

When to Call a Professional

Although some issues with your underfloor heating system can be managed with a do-it-yourself approach, specific problems necessitate professional expertise.

From leak detection and repair to addressing electrical faults and system flushing, it’s good to know when to call in the professionals.

We will now examine these scenarios in depth.

Leak Detection and Repair

Detecting leaks in underfloor heating systems can be complex and requires specialised methods. Professionals use thermal imaging cameras or heat scanners to accurately detect leaks. If a leak is detected, immediate repair is the best option to prevent further damage to the system and your property.

Electrical Faults

Electrical faults, such as earth leaks or wiring board issues, can cause significant malfunctions in your electric underfloor heating system. These issues should be addressed by a qualified electrician who can safely assess and repair the fault.

System Flushing

Central heating system flushing involves sending cleaning chemicals through the pipes of your underfloor heating system to clear them of any corrosion (chemical flush), sludge debris, or rust.

Understanding what a heating system means in this context, specifically underfloor heating, can help you appreciate the importance of this process.

Best performed by a professional, central heating system flushing can help remove debris and improve the overall efficiency of your underfloor heating system.


To sum up, regular maintenance and understanding common issues can help keep your underfloor heating system running smoothly.

By taking preventative measures, scheduling annual servicing, and being proactive in detecting issues, you can extend the life of your system. Remember, when in doubt, don’t hesitate to call in the professionals. After all, a warm, comfortable home is well worth the effort!

Frequently Asked Questions

Why is my underfloor heating not working properly?

Your underfloor heating may not be working properly due to various reasons such as setup issues, a faulty controller, flooring problems, or trapped air in the pipes. You should troubleshoot these potential issues to determine the cause.

How do you reset underfloor heating?

To reset your underfloor heating, press and hold the Mode and i buttons on the controller for at least 10 seconds. After 4 seconds, the controller will switch to test mode. This will reset the thermostat.

Why is my underfloor heating zone not heating?

Your underfloor heating zone may not be heating due to a faulty connection within the actuator, wiring board, or thermostat. If the system is not heating up at all, it’s best to seek professional help for resolving the issue.

How often does underfloor heating go wrong?

Underfloor heating rarely goes wrong if installed and set up correctly, with most issues being easily resolved through thermostat adjustments or simple electrical/lifestyle changes.

What flooring material is best for underfloor heating?

Ceramic and stone tiles are the best flooring materials for underfloor heating, as they conduct heat effectively.

Written by
James Elston
James Elston Director Of Boiler Central
Posted on: 11th January 2024
Topic: Boiler Advice

James Elston is our resident boiler replacement and heating expert here at Boiler Central. With over 20 years experience in the boiler installation industry, James ensures that he knows everything there is about our Gas Safe boiler installations, energy saving and home heating solutions. This can be from simply procuring the latest best combi boilers, to reviewing and ensuring that Boiler Central maintains the highest standards across our boiler installation company.

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