Common Underfloor Heating Problems & How To Fix Them

Underfloor Heating Problems

If you have underfloor heating, it’s useful to know what kinds of warning signs to look out for and what steps you should take to repair problems and get your system up and running again.

Underfloor heating offers a wealth of benefits for homeowners. Most of the time, you’ll enjoy comfort and cosiness without any problems, but like any heating system, it is possible to encounter glitches and hiccups.

If you have underfloor heating, it’s useful to know what kinds of warning signs to look out for and what steps you should take to repair problems and get your system up and running again.

In some cases, you may be able to attempt maintenance and repair jobs yourself, but in others, it may be best to seek expert help.

This guide will provide you with useful information to help you spot underfloor heating problems and find solutions.

Types of Underfloor Heating Problems and How to Solve Them

The problem: Air in the System

If you’re used to central heating, you may be familiar with air getting trapped in the system, which prevents your radiators from working properly.

If there’s air trapped in the pipes, this affects the flow of water, and it may cause you to develop cold spots or for the temperature to fall in general (please read our Bleeding Radiators Sequence guide with handy instructions on how to overcome this problem).

The same problem can affect underfloor heating. If there’s air trapped in the pipes, you may notice that the temperature isn’t as high in some areas as others or that the overall temperature is lower than normal.

Air in the system isn’t a major issue, but it’s natural to want your heating to work effectively, especially in winter, and this is why it’s beneficial to address the issue swiftly.

Air in the System: The solution

If you have air in your pipes, you may need to bleed the system. This involves dislodging the air and refilling the system to increase the pressure. Isolate the part of the system that is affected and turn off the actuator.

Then attach hoses to both the valve and a drop-off point. The hose that is attached to the valve should also be connected to a cold water supply.

When you bleed the pipes, the waste will drain away, the air will be dislodged and then you can refill the system.

Make sure you close the valves that you are not venting and that all valves are shut once you’ve finished.

Our step by step guide How to Bleed Underfloor Heating will help you with exactly that.

If you’re not confident about tackling this job yourself, don’t hesitate to call an underfloor heating expert.

The Problem: Debris in the System

When you connect the heat source, for example, the boiler, it’s essential to power flush through the system fully to remove debris and prevent exposure to iron oxide, which can cause damage to the pump and result in the mixing valve malfunctioning.

Debris in the System: The Solution

When installing a new underfloor heating system or new components, for example, a boiler, it’s wise to call in the professionals. They will ensure that every stage of the installation process is completed properly to minimise the risk of damage and maximise functionality.

The Problem and How to Fix it: Part of the System isn’t Heating up Properly

There are various possible causes when part of the system isn’t working properly. If there’s an isolated area where the temperature is lower, this may indicate:

  • Air in the system
  • A pin beneath the actuator: sometimes, the small pin beneath the actuator can become stuck. If the pin is stuck, use silicone spray or a pair of pliers to gently dislodge it.
  • Failed actuator: in most cases, a failed actuator is symptomatic of an electrical fault, which should be addressed by trained engineers.
  • Thermostat fault: you should be able to reset your thermostat by consulting the user manual. If you still have problems, this may indicate an electrical fault, which will require expert attention.
  • Thermostat errors: sometimes, the thermostat may not be set up correctly, and this may mean that one room is colder than the others. Errors are often flagged up on the thermostat itself, so keep an eye out for warning lights or advisory notices.
  • Wiring faults: any issue that involves wiring is best left to the experts.

The Problem: Unsuitable Flooring

The flooring you fit can make a difference to the impact of your underfloor heating system. There are some materials that are much better than others when it comes to feeling the effects of underfloor heating. The combined TOG value should not exceed 2.5.

Unsuitable Flooring: The Solution

If you already have underfloor heating and you’re thinking of changing the flooring, ask for advice beforehand and make sure the materials you choose are compatible with an underfloor heating system.

The Problem and How to Fix it: The Entire System is Down

If you don’t have any warmth at all coming from your underfloor heating system, this may be symptomatic of several different issues, which include:

  1. Circulation pump failure: if the entire system is down, this may indicate that the circulation pump has failed. It’s best to seek professional advice, as this is an electrical problem.
  2. The isolation valves are closed: if the isolation valves on the manifold are at 90 degrees, this means that they are closed. The valves should be open.
  3. The blending valve pin is trapped: take off the valve head cover to check if the valve pin is trapped. If it is pinned down, you can use silicone spray or a pair of pliers to free it.
  4. The boiler isn’t working: if there’s no flame and the boiler isn’t running, consult a heating engineer.

The Problem and How to Fix it: The Pump is Running Constantly

If the pump is running constantly, this may suggest:

  1. The pump relay is stuck: if the pump relay is stuck on the wiring board, this indicates an electrical problem, which should be addressed by a qualified engineer.
  2. Thermostat errors: if the thermostat isn’t set correctly, follow instructions in the user manual to adjust the temperature or reset the thermostat. If you have a wireless thermostat, you may need to switch the batteries.
  3. Actuator failure: if the actuator has failed, you’ll need to contact an electrician.

The Problem: The Pressure is Too High

If you check the pressure and it’s too high, this may indicate that the filling loop has been left running, there is air or a blockage in the system or the diaphragm has been damaged.

The Pressure is Too High: The Solution

Check to make sure that the valves at either end of the filling loop are closed. If there is a blockage in the system, you could try and bleed the system or call an engineer for advice.

If the pressure fluctuates when the speed of the pump changes, this often indicates an obstacle.

If you think there may be issues with the diaphragm, see if water flows from the expansion vessel when you press the needle located on the Schrader valve (this can be found on the underside).

If water does flow, this suggests that the diaphragm is damaged and the vessel will need to be replaced.

In some cases, it may just be a case of the diaphragm being void of air, which causes increased pressure as there is no space for the water to expand.

The Problem and How to Fix it: Low Pressure

If your system is losing pressure, there may be several different causes.

Low pressure may be linked to leaks, as well as issues that affect the valves and the expansion vessel.

In the vast majority of cases, these are problems that should be fixed only by trained professionals.

Seek Expert Advice If Needed

If you have underfloor heating, it’s unlikely that you’ll encounter problems on a regular basis, but it is possible to experience issues that may affect the impact of your heating system.

If you spot any of these signs or you’re worried that you’re not getting the best out of your system, it may be possible to troubleshoot and attempt repairs, but often, it pays to seek expert advice.

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