A wood pellet boiler and solar thermal panel provides 100% renewable heat and hot water
With a large farmhouse to heat and a "granny annexe" planned for the future, plus the hot water demands of a large family, the challenge on this project was to come up with a reliable, carbon-neutral heat source that had the capacity to do the job now and cope with the increased load in the future.
The microgeneration solution consisted of a 32kW biomass wood pellet, three draught boiler with an automatic screw feeder, working in conjunction with a 4m² solar panel using evacuated tube technology. In addition, the boiler would be fitted with a digital control capable of being modulated at ten different settings to ensure maximum control and therefore operating efficiency.
The really innovative element was the efficiency-improving configuration. By linking the biomass boiler to a 300 litre buffer tank, the boiler did not have to fire up at short intervals but could run for a good length of time, bring the buffer tank up to a very high temperature and then switch off.
The buffer tank could then act as the 'energy store', delivering
hot water to the Gledhill mains pressure hot water cylinder.
This acted as the hot water 'hub', supplying hot water for washing and bathing as well as the underfloor heating system.
To reduce boiler load on sunny winter days and in the summer,
the solar panel provides an added boost to the water temperature.When integrated with evacuated tube solar thermal collector system, this setup gives an optimal sustainable solution.