Ask the expert: Heat Mat underfloor heating

Heat Mat is one of the leading manufacturers of electric underfloor heating in the UK. Here, Heat Mat’s Technical Director, Dave Green, shares his tips with BEW customers, from best-practice basics to some dangerous mistakes.

5 things to remember when installing under-floor heating:

  1. Make sure everyone working on site is aware that underfloor heating is being installed and understands how his or her task fits into the project. For example in a bathroom install, let the tiler know before they begin to lay the floor to avoid any accidental damage with a grout tool or tile cutter. 
  2. Choose the right system – Heat Mat will work closely with you and BEW to specify the right system for the job. It is of paramount importance that the system suits the environment in which it’s being fitted and the final floor covering above. A 110W heating mat is only suited to well-insulated properties, while loose heating cable is far better in a small awkward space like an en-suite than heating mat. An under-laminate system, meanwhile, can’t be installed under tiles (the clue’s in the name). 
  3. Never screw or staple a system down. This is incredibly dangerous, for obvious reasons (you are working with electrical cables after all). Use the fixing tape provided or a hot glue gun on the mesh to secure the mats in place. 
  4. Cover the coldtail in flexible tile adhesive. The tile adhesive must be flexible to avoid expansion and cracking as the system heats up. If the coldtail connection is not covered it may burn out. 
  5. Create an even floor base, using insulation boards, leveling compound, tile adhesive or similar, to prepare a safe and reliable foundation for the UFH system.

5 things to avoid at all costs:

  1. Never cut cables to make a system fit. Talk to BEW and Heat Mat about the project and they will specify the correct sizes of mat or cable for the space. 
  2. Avoid installing the floor sensor close to other heat sources such as hot water pipes or radiators. This will throw off the product’s sensor, tricking it into thinking the room is hotter than it is. 
  3. Never leave any sections of a heating mat/cable in the open air or beneath fixtures and fittings (such as a kickboard in a kitchen). Every part of a Heat Mat underfloor heating system must be covered by flexible levelling compound, screed or tile adhesive except our Combymat system (overlay boards are available for this). 
  4. Don’t cross cables over each other. This can cause them to burn out and cause system failure for your customer. The space between the cables is essential: this is what provides the output of the system. By crossing cables, a large amount of heat is generated in a confined space that can damage the cable throughout.
  5. Never tape over the end joint or coldtail connection. This is a common error. We’ve seen installations where duct tape has been used to stick down the end joint. Using tape will create an air pocket around the cable and prevent heat from escaping, causing the connection to fail. 

Last but not least…pay attention to Lot 20

The Lot 20 regulations will imminently affect underfloor heating. As an electric underfloor heating manufacturer we intend to abide by these rules and offer the most energy efficient systems to our customers. 
Lot 20 will herald the end of the manufacture of manual electric underfloor heating controls without a timer function; a controller without a thermostat timer is no longer compliant. Our NGT thermostats enable a system to be compliant and the majority surpass the minimum 38 out of 40 score. In response to Lot 20 we will be introducing a modified version of our manual TPS thermostat in early 2018.

Tips, training and more

If you’d like to find out more about how to correctly fit underfloor heating, you can join Heat Mat on one of their award-winning installer training days in 2018. The team will be visiting Portchester, Fareham in January and Hastings in February, with sessions planned elsewhere in the UK for the remainder of 2018.
The FREE training days run from 9am – 2pm for information please email [email protected]
For more on Heat Mat products, and general advice on the best products to choose when installing underfloor heating, speak to your local BEW branch