There are many heat sources that can be used for Hydronic Underfloor Heating.
Hydronic underfloor heating can be supplied by all domestic boilers that produce hot water. As with all heat sources, it is important to size them correctly to get the best efficiency from them. A typical 100m² house has a heat loss in the region of 5kW, using a large boiler that cannot modulate below 10kW heat output will mean that it is always short cycling, even on the coldest day of the year.
The efficiency of Air and Ground source Heat Pumps is heavily influenced by water temperature. Optimising a hydronic underfloor heating system to operate with reduced water temperatures allows significant reductions to be made on running costs compared to conventionally sized radiators.
Heat pumps tend to have high flow rate requirements for efficient operation so consideration should be given to the use of low loss headers or other intermediate devices to allow the underfloor heating system to efficiently regulate room temperatures without adversely impacting the heat pump efficiency.
Solar Thermal, Biomass and Unregulated Heat Sources
Thermal stores are typically used to collect heat from unregulated heat sources, such as solar thermal or heat sources which are unable to rapidly modulate to demand such as biomass boilers.
The low water temperature requirements of Hydronic underfloor heating means it can extract useful heat from a thermal store fed by a variety of heat sources for much longer. If a solar thermal system is able to charge a thermal store up to 70°C or 80°C, then a conventional radiator system will function just as well as Hydronic underfloor heating for a while.
However, the heat output of conventional radiators will dwindle as the temperature within the thermal store lowers once the sun begins to set. Conversely, a Hydronic underfloor heating system will continue to work a peak power and efficiency until the water temperature falls much lower to its design temperature. In a well-designed system, this can enable the thermal store to be significantly smaller, costing less and taking up less space, while still providing better and more consistent heating performance with Hydronic underfloor heating.
Always more efficient
Supply of heat to a hUFH system is by no means limited to the above heat sources, but in short, Hydronic underfloor heating can always improve the operating efficiency of any heat source by reducing its operating temperature.