Boost boiler performance with UFH

Nu-Heat UFH system with a boiler

According to the Energy Saving Trust, boilers account for around 60% of annual energy bills, and by replacing an old gas boiler with an A-rated high-efficiency condensing boiler and improving heating controls, homeowners could save as much as £300 per year.

One way to enable a modern condensing boiler to operate more efficiently is to link it to a warm water underfloor heating system.

UFH and efficiency

UFH has the potential to be the most efficient type of emitter and will work effectively and efficiently with combi, system, gas, oil, LPG and condensing boilers.

Because the surface area of the floor is far greater than that of a radiator, the same room temperature can be achieved with much lower flow temperatures. Where a radiator may be heated to between 60˚C and 75˚C, UFH can often achieve the same performance running at just 50˚C, which will allow the boiler to operate efficiently in condensing mode.


Condensing boilers and UFH

UFH offers a way to make the most of the efficiency aspect of condensing boilers. Condensing boilers reduce carbon dioxide emissions and improve household efficiency, resulting in reduced fuel bills.

They work on the principle of recovering as much as possible of the waste heat that is normally ejected into the atmosphere from the flue of a conventional boiler. The combustion process in the boiler combines the fuel with oxygen from the air, but as well as releasing heat there are by-products of carbon dioxide and water. The water is in the form of vapour, which is the steam that can be seen emitting from many older boiler flues. The critical temperature is called the ‘dew point’; this is when the vapour will condense into liquid. Condensation releases a significant amount of latent heat energy from the vapour, leading to the efficiency gain.

In order for a boiler to operate in condensing mode the return temperature of the heating system must be lower than the dew point (53°C). Radiators sized traditionally to a flow temperature of around 70°C with a return temperature of 60°C are outside of a condensing boiler’s range, so cannot make the most of its capabilities; but UFH, requiring a flow temperature of 50°C flow and 40°C return, is ideal to take advantage of this and offer better energy efficiency than a radiator system.


The Green Deal encourages homeowners to upgrade their insulation through options such as double-glazing, cavity wall insulation, roof insulation and good draught proofing. Upgrading the property’s insulation is always worth considering when installing UFH and is absolutely essential if you are integrating a heat pump with your system and are hoping to benefit from the Domestic RHI.

System design and efficiency

The quality of the system design is key to good performance with UFH.  It’s important to establish the most suitable floor construction and flow rates for a property.

Nu-Heat takes elements such as existing insulation and heat loss calculations into account to ensure that not only the desired amount of heat is provided but that the system is also economical and efficient. Boilers need to be sized in line with upgrades in insulation and, to ensure that maximum efficiency is achieved, this should be an integral part of the design element for a new build or complete retrofit UFH system.

With the right system design, UFH can be successfully installed in nearly any property – even older, period properties, with lower levels of insulation thanks to new LoPro®Max – and still perform.

To find out more about UFH for your project, call 0800 731 1976 or visit


Nu-Heat’s experts in underfloor heating, heat pumps and solar thermal share product information, company insights and industry knowledge in our blog.