Dragon Renewables Biomass Cambridge


Passive House Felsted, Essex

Example Project

Wood Fired Boiler and Solar PV Installation

We needed to provide a system to supply hot water and some heating for this project.

  • F12 Wood Fire and Thermal Store installation
  • Underfloor Heating and Heater Batteries installation
  • Solar Photovoltaic Panels installation
  • Solar Thermal installation

Example project

Passive House - Felsted, Essex

We needed to provide a system to supply hot water and some heating for this project. The clients did not want a complicated self lighting self cleaning boiler, and did not have the space for one. The client wanted to burn logs as he has a plentiful supply which were already stored under cover.

We had already put in a similar system in Pin Mill in Suffolk and suggested this. The client visited the Pin Mill installation and was convinced.

We suggested a Wood fire F12 which supplied 1.2kW to the room and 10.8kW to the water with an 82% efficiency. An open fire is about 20% efficient, whereas a pellet boiler is 92% efficient. With this output we needed a large thermal store so the stove could run at full burn for a optimum amount of time. We selected an Akvaterm EK1000 with heat exchange coils to supply mains hot water and the solar thermal system. This store has 1000 litres of water and will hold approximately 88kWh of heat at 70°C. The heat loss of the building as designed was to be 3.6kW. One store load would supply 24hrs of heat to the house when the outside temperature was -1.8°C, the idea being that the stove would be lit once a day in cold weather and would supply a day's heating.

We installed underfloor heating in the floor slab of the north side of the house as this was felt to be the only area where the sun would not reach on a winter's day. We also installed two heater batteries into the fresh air supply attached to the mechanical heat and ventilation recovery (MHVR) system. The system extracts stale and moist warm air from the property which is used to preheat the incoming fresh air. In very cold weather the heater batteries (which look like small car radiators) have hot water pumped through them and this warms up the air to around 18-20°C thus keeping the air fresh and the property well ventilated and at the desired temperature day and night. The hot water for the underfloor and the heater batteries is taken from the middle of the thermal store.

The upper section of the store is used to supply hot mains water from the copper finned heat exchanger coils. These coils are interlaced with secondary coils which provide heat to the store through Spring, Summer and Autumn from the four Gasokol flat in-roof solar hot water panels . These supply all the hot water needs and, if necessary, after a long period lacking insolation a short firing of the wood stove brings the store back up to temperature very quickly .

To complement the heating system we also installed 4kWp of Solar Photovoltaic panels which provides the clients with a negative electricity bill.

 

More info?

For more information, or to arrange a free telephone interview about your requirements, please contact Jonathan Cooke today

Saffron Walden (01799) 598 086

mail@dragonrenewables.co.uk