Underfloor heating systems (UFHs) ensure a cosy environment for us throughout the winter. However, with time, they may develop certain technical issues that minimise or hinder their functioning. Understanding those problems and their key causes is pertinent to finding a reasonable solution. This will ensure an uninterrupted heating supply, allowing you to enjoy well-heated interiors.

In this blog, we will look at some key problems of (UFHs), know their cause and look for a feasible solution. Let’s begin:

When a Single Zone Does Not Heat Up

Well, it is straightforward to locate this issue. All related to it is that your feet are cold in a certain area compared to the other parts of the floor. There can be more than one reason for this problem.

Underfloor Heating Actuator Problems

When it comes to issues with the actuator, there are two possibilities. Either the pin with the actuator is stuck, or it has completely failed.


To solve the first issue, remove the actuator and free the pin. You can use a silicon spray or long pliers. If you find that the actuator has failed, connect with a professional electrician to solve the problem.

Underfloor Heating Thermostat Problems

The issues related to the thermostat can be either related to any fault with its functions or any error in its settings.


  • The electricians can rectify a faulty thermostat by checking its battery power that whether the battery is producing enough power for it to start.
  • Otherwise, setting errors can be rectified with the help of going through the manual guide and moving accordingly.

Issues with the Underfloor Heating Parts

Issues of the underfloor heating parts can be like

  • Blockage in pipes
  • Fault with the wiring
  • Gauges are not opened correctly


To rectify a blockage issue in an underfloor heating (UFH) system, begin by isolating all UFH zones, focusing on the one that isn’t heating up. Remove the actuator and attach a hosepipe to the flow valve on the manifold, connecting it to a cold mains tap.

Meanwhile, attach another hose to the drain-off point on the manifold, leading it to a waste outlet. With both taps, the drain-off point and the flow point open, turn on the cold tap to flush water through the problematic zone, addressing any potential blockages or circulation issues.

If the gauges are not opened correctly, consult with the manual and follow the instructions provided by the manufacturer to rectify the problem. Whereas to tackle the fault with the wiring, hire a qualified electrician.

Underfloor Heating Problems & Their Solutions

Multiple Zones or Entire System is Not Heating Up

This is another problem that may happen; in this case, the whole system stops working. There can be so many reasons for this issue:

  • The circulation pump has stopped working.
  • The pump relays on the wiring boards have malfunctioned.
  • The isolation valve is closed.
  • There is no power in the wiring boards, and the boiler is not giving a fire signal.


Besides the isolation valve issue, you have to contact an electrician who will resolve the wiring and pump-related issues.

Increase in UFH Pressure

An increase in UFH pressure can be on behalf by the following reasons:

  • The expansion vessel may have failed and stopped working.
  • The filling loop is mistakenly on.


  • To determine if the expansion vessel is functioning properly, press down on the needle within the Schrader valve located underneath it. If water is released, it indicates a ruptured diaphragm within the vessel, necessitating a complete replacement.
  • Alternatively, if the diaphragm lacks air, it hinders water expansion during heating, leading to rising pressure. To address this, release excess water pressure through the relief valve. Then, use a foot pump on the Schrader valve of the vessel, inflating it to 2 bar. Finally, replenish the waterside to achieve the standard working pressure.
  • To resolve the filling loop problem, check whether the valves on the flexible hose are closed, followed by disconnecting the filling loop.

Pump Is Running Continuously

When the pump is running continuously, there can be an issue with the pump relay that is sticking to the wiring, the actuator is failing, or an issue with the thermostat.

  • To reset a thermostat, simply go through the user’s manual. Also, check the battery to see whether it’s delivering the appropriate power.
  • If the actuator fails or the pump relay is not functioning properly, consult an electrician.

Pressure Drop on System

It is not always the same that the pressure will be higher than usual; at times, it may drop.


  • Give a quick scan to your system and check whether any of the pipes, cylinders or valves, like the temperature valve, pressure valve, or boiler blow valve. Check carefully whether these components are leaking or not.
  • Do not forget to hire a qualified engineer who will look at and resolve these issues.

Underfloor Heating in Barnet


UFH systems may develop certain faults that can be associated with the system valves, pipes, control unit or wiring over time. Hiring professional technicians who will check thoroughly and sort out the specific issue is recommended. K M Flow Screed is a house of trusted professionals. Our staff is knowledgeable, well-equipped and experienced to resolve all your issues of UFH. Hire our licensed services and enjoy error-free UFHs.