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Over recent years the cost of heating has gone up dramatically meaning UK residents are increasingly carrying out insulation upgrades to reduce bills. Often linked to this type of major refurbishment is the need to upgrade the heat source – and this is where you come in, as it offers the perfect opportunity for you to promote underfloor heating (UFH) to the existing property market in place of radiators.

What makes a system fit for purpose?

The most important aspects of any heating product from an installer’s point of view are likely to be ease-of-use, robustness, reliability and heat output capability – in a retrofit situation the overall height build-up may also be important. A UFH floor construction that delivers on these critical aspects is what all installers are looking for.

The choice of heat source depends on the fuel supply – if gas is available a modern condensing boiler will work very efficiently with UFH as the low flow temperatures allow it to run in condensing mode for more of its operating time, making it the most economical choice. Alternatively, oil, lpg or any source that can deliver controlled heat at the required temperature can also be used.

There can be situations where a heat pump will be a viable option, usually where the property is undergoing major renovation to bring insulation into line with current building regulations, especially where direct-electric heating is being replaced. The flow temperatures required must be low enough to allow it to operate efficiently and deliver a sensible CoP, so it is always worth checking with the system supplier.

Good system design is crucial to the success of any heating system, particularly UFH in a retrofit project. Before you start…


  • Get heat loss calculations done, as this will determine whether the system shall perform as required.
  • Upgrade insulation; typically this would include double-glazing, loft insulation and cavity or solid-wall insulation.
  • Investigate the Government’s Green Deal funding initiative as some of the upfront costs of insulation upgrades and UFH could be offset against future energy savings.

 Step-by-step – the easiest way to install Nu-Heat’s LoPro10® retrofit UFH

  1. Clear the floor area, repair and level the floor as required using self-leveling compound or replace/screw down uneven suspended timber floors.
  2. Lay pre-routed panel and castellated panel for pipe run back to manifold following the system design drawing supplied.
  3. Lay ‘pipe run’ panel where shown on the design drawing. This panel gives plenty of flexibility to install multiple pipes back to the manifold.
  4. Run 10mm pipe from the manifold to each designed zone.
  5. Fill and pressure test the system. This is a crucial part of any UFH installation as it ensures the system is watertight before final floor finishes are laid.
  6. Lay self-leveling compound to cover edge ‘pipe run’ panel and leave to dry for 24hrs.


  • Carry out all 1st fix mechanical pipework and electrical wiring, building and plastering work before installing retrofit UFH, which should be fitted at 2nd fix stage to avoid damage to pipes or panels – this floor construction can almost be considered in the same way as a floor finish.
  • Ensure the panel has a firm base on which to sit to remove any possibility of movement.
  • Pay particular attention to which end of the room will have turns panels; the other end will have straight panels butted up to the ‘pipe run’ panel.
  • Check which coil lengths go in each zone as they may vary in length and only trim each one to the length shown on the system design when all the coils have been installed.
  • Use the edge batten and the 15mm height of the panel to achieve an even, level finish for the self-leveling compound.

Final floor finishes

Tiles, engineered timber, carpet and vinyl are all suitable for use with retrofit so long as the supplier’s guidance on best practice is followed.

  • Tiles – a de-coupling membrane and flexible adhesive should be used to guarantee performance.
  • Engineered timber is recommended instead of solid hardwood flooring, as its structure is inherently stable. Glue, butt joint and free float the floor over the panel. A 5mm acoustic layer can be fitted under the panel on suspended timber floors if required.
  • Carpet plus an underlay suitable for UFH with a combined maximum tog value of 2.5 is recommended.

Customer satisfaction

Due to its good response times, a retrofit system such as LoPro®10 can be set up, controlled and run in the same way as a standard radiator system with similar system times and control settings. This means that homeowners do not have to radically change the way they use or program their heating system.

Warm houses, happy customers and a new market to make the most of in these trying economic times – retrofit UFH has got to be worth investigating.

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