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HomeHelp and adviceDealing with common issues when levelling over underfloor heating: Part 2

Dealing with common issues when levelling over underfloor heating: Part 2

Having discussed preparation for underfloor heating installations last month, Alan Collins and Martin Pouncey, technical training and site support managers at Instarmac, elaborate on the process of product selection and installation

That’s preparation done! Let’s take a look at product selection. Choosing the correct materials to go over underfloor heating can be tricky and is always dependent on the system and the substrate you are working with.

Our number one tip would be to contact the adhesive and leveller manufacturer and seek technical advice before embarking on your project.

We are always happy to offer advice over the phone or in person. Don’t stand on site worrying about which product to use, just give us a ring and we will talk you through it.

Alan’s Top Tip! Never use duct tape to stick your cables to the floor. The surface of duct tape is non-porous, therefore no cementitious product will adhere to the tape and you will end up with hollows.
Tip 6: Always apply a leveller over the underfloor heating system, prior to the adhesive, to encapsulate and protect the system. This will not only help shield the system from damage often caused during installation but will prevent the system being ripped up and replaced if your customer changes their flooring choice in the future.

Encapsulating the system will also improve thermal conductivity allowing heat to be distributed evenly across the floor eliminating cold and hot spots.

Tip 7: If you are going to be installing underfloor heating during the colder months, our advice would be to run the system at 15°C when you begin to fix the tiles. Heating the system up will give you a better substrate to tile to, eliminating cold spots and freezing adhesive.

Tip 8: When fixing tiles on to an underfloor heating system, whether it be inscreed or retrofit, always use the back buttering method to ensure 100% coverage to eliminate air voids. Air voids result in delamination issues – a costly reason to go back to site!

Martin’s Top Tip! Once tiling is complete and before your customer can enjoy their lovely warm house, you need to let the floor cure for 7 days. Turning the system on before 7 days will cause thermal shock and delamination.

After your 7 days is up, it’s critical you heat commission the floor, whether you have commissioned the slab or not.

As explained in last month’s column, heat commissioning requires the installer to slowly increase the water temperature by 5°C per day, up to the systems maximum temperature. When you have reached this temperature, slowly decrease the system by 5°C per day until it reaches equilibrium. This needs to be carried out on the manifold and not the room or boiler thermostat. And that’s it! Follow our advice and you should have a problem-free installation every time! We hope you found this article helpful.
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