7 Classic UFH installation errors. And how to avoid them

7 Classic UFH installation errors. And how to avoid them

As the UK moves towards its net carbon zero goals, the installation of underfloor heating systems is growing in popularity. However, it’s not without its pitfalls. This article looks at seven of the most common mistakes made during UFH installations and why it’s best to avoid them.

  1. Failing to prepare the floor

The base floor must be properly prepared ahead of installing the UFH system. The screed, thermal insulation and UFH pipes cannot be put down on uneven surfaces. Careless preparation of the base skipping the levelling and cleaning stage means it will not provide stable support for the screed, leading to cracking. If the screed cracks, there is a risk that the UFH pipes will be damaged and may leak. If the base floor is not completely dry before laying the finished floor, there is the possibility of unpleasant odours, fungi and mould developing. As well as in the case of tiles not sticking and they start debonding.

  1. Overlooking the conduit

It’s easy to overlook the pipe conduit when you’re pressed for time, but doing so can seriously affect the UFH system post-installation. The conduit acts as a protective sleeve where pipes rise from the screeded floor or travel through an expansion strip. It is important to protect the pipe with conduit as it protects the pipework from damage and insulates the pipe, thus preventing an excessive build-up of heat in one area, which can often cause overheating in some areas. The time invested in installing conduit on your UFH pipes will result in a better system output and greater customer satisfaction. It could save you from being called back for remedial work later.

  1. Failing to fill the system correctly

It’s essential to properly fill the UFH system to ensure no air is trapped, which could cause poor performance. In addition, by properly filling the system, you can be confident that it will operate effectively once the final commission is complete.

The key points to note when filling the system are:

  • Ensure that each loop is filled one by one and that you fill from the furthest point from the fill & drain point.
  • You must use the fill and drain points on the manifold and not the boiler filler loops
  • The rest of the system must be isolated from the manifold.
  • Once complete, vent the system using the air vents from the manifold
  • We don’t recommend using AAVs on manifolds as this tends to be a lower part of the system so of not much use, and is often boxed in, so over the years could start to leak.
  • This process ensures air is not trapped in the system
  1. Skipping or getting the pressure test wrong

A pressure test is a vital element of ensuring the UFH system is fit for its purpose, as it’s critical to ensure the pipework operates without leaks when pressurised. Pressure tests should be completed at 4-6 bar for a minimum of 1 hour before reducing to working pressure (1-2 bar) before laying flooring or screed. The test allows you to check for leaks and that the pipes are expanded to ensure good heat transfer once the screed is dry.
Ensure you complete the pressure test with water or air if there is a risk of frost.

Check out our video on performing a UFH system pressure test.

  1. Not considering the final floor covering

Modern UFH systems are compatible with a huge variety of floor coverings. Still, you must know what finish your customer wants to install before your Multipipe quote is finalised, as the type of floor covering determines the heating efficiency. For example, ceramic tiles have a very different thermal output compared to carpet. Not taking account of the final kind of floor covering can mean the difference between a system working or not (imagine covering all radiators in a blanket!).

  1. Not following the installation drawing plan

Our bespoke UFH solutions come with a full drawing plan to aid installation. We highly recommend following this plan as it’s created to ensure the system operates at maximum efficiency and provides the heat output required. The project is also designed to ensure that you have the right amount of materials for the job – deviating from the plan may mean that you run out of equipment and incur additional costs. Also, using the hydraulic balancing information will help to speed up your commissioning time and ensure all rooms heat evenly.

  1. Not considering future changes to the room layout

It’s easy to think you’re saving your customer a few pounds by not running UFH throughout the entire room, for example, under the kitchen units or island, but this is not a smart move long term. With proper care and maintenance, your Multipipe UFH system will likely last at least 50 years. However, the homeowner will probably change their kitchen design at least once in that timeframe. By failing to install UFH under the units, you risk leaving them with cold spots in the future. Contrary to popular belief running the system under units will not cause damage or the contents of the cupboards to overheat.


By avoiding these mistakes, you’ll be well on your way to a perfect UFH install that will provide comfortable warmth for your customer for years to come.

When requesting a quote for a bespoke Multipipe UFH system, you can be sure we’re on hand to offer advice at every stage. For example, we can help calculate heat losses, ensure you have the right materials and the correct amount of them, and advise on the best system for the floor type on your project. To learn more about Multipipe’s UFH solutions click here