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Modern wood chip or pellet boilers offer the warmth and comfort of wood heating while being highly efficient, clean burning and totally automatic, saving you time and money.

Chip or Pellet boilers are lit automatically and continue to operate without manual intervention. Automatic fuel supply and thermostat means you can relax and enjoy the comfort of chip/pellet heating at the switch of a button. Automatic ignition means that lighting the boiler is convenient and easy. Modern chip/pellet boilers are self cleaning so you can forget the daily cleaning chore of traditional solid fuel heating systems. The ash pan needs to be emptied bi-weekly, or less frequently, depending on service.

These systems must comprise the main heating system of the house and can be run on wood chips and/or wood pellets.

Flues: The flue is used for the exhaust of the boiler or stove. It can be installed through a chimney or outside the building. The flue must be installed to current Building Regulations.

Some things to look for would be:

• It is above the eaves line by about 1metre or 600mm if coming out near the roof apex.
• It is twin walled and insulated.
• It has a cowl or hood on top to help prevent down draught.
• It should be separated from any combustible material.

Constructional Hearth: A constructional hearth should be placed under a stove to separate the stove from combustible material and to provide protection from the threat of fire. The constructional hearth could be a metal or a non-combustible plate. The appliance should not be placed close to the edge of a hearth or any combustible material.

Air Supply: A stove or boiler must have a secure air supply for safe operation. This can be either in the form of a controlled dedicated air supply directly to the appliance, or in the form of a permanent ventilation opening to the room in which the appliance is located. Best practise is to rely upon dedicated ventilation and not on air infiltration and/or leakage in the room. The size of the opening depends on the size of
the appliance. Your installer should be able to size this correctly. In addition, extractor fans may interfere with the operation of the appliance causing smoke to spill out of the appliance into the room so please consult with your installer.

Thermal Mixing Valve (Anti Scald Valve): Best practice calls for the fitting of a thermal mixing (anti-scald) valve. This applies to all hot water systems and not just solar heated water systems. With the current recommendation to store hot water at 60°C to prevent the growth of legionella bacteria it is becoming more of a consideration to install thermal mixing valves. A thermal mixing valve mixes cold and hot water together to ensure the water temperature is safe for people to use.

Bulk Fuel Storage: All biomass boiler installations shall require the provision of bulk storage. It shall be required to meet local building and fire regulations. The ONORM M7137 Standard shall be used as a guideline for DIY bulk storage units. Bulk storage capacity shall be able to store a minimum of 3 tonnes of wood pellets (80% of a typical houses’ requirement for one year).

Buffer Heat Store: It is a recommendation that a buffer or accumulator tank be incorporated as part of domestic wood pellet / chip boiler system installations where appropriate. A buffer or accumulator cylinder in a domestic biomass heating installation is a primary heat storage/distribution cylinder, which is heated by the boiler to a set temperature and can store the resulting high temperature water for long system standstill periods, until heating or hot water is required. A buffer / accumulator reduces the on/off cycling of wood boilers by “smoothing” the heat
output to the dwelling. The buffer or accumulator capacity should be calculated in accordance with your manufacturer’s recommendations. A rough guideline for establishing the volume of the buffer is available from EN303-5 and from the REIA training manual and is in the region of 55 to 65 L/kW of the rated boiler size.

The use of a buffer / accumulator is noteworthy in the following situations:

• Where the boiler does not have full modulation capabilities: the use of a buffer will smooth the heat output to the dwelling.
• In situations where the boiler is not capable of supplying the full heat demand of the house, a buffer tank will allow the boiler to run for longer at optimum efficiency extracting maximum potential from the boiler and fuel.

Thermostats
Thermostats are used to control the temperature of an area or space. You should consider what the optimum location of the thermostat is; usually it is the living space where you will spend most of your time. It is very worthwhile to have all main rooms “zoned” and fitted with their own thermostat.

Pellets
Quality pellets are essential to ensure clean combustion and trouble-free operation of your appliance. When buying pellets, consumers should consider those that are supplied with a quality mark and with a complete fuel analysis. Often this information will be printed on the packaging.

Pellets can be purchased in bagged or bulk form. For bulk purchases, a dry covered storage area is required. Generally bulk prices are more competitive than those for bags. Wood chips are generally sourced locally. It is important that the fuel used (quality, size, moisture content) is suitable for the appliance; your supplier will provide you with these details.

Poor pellet quality can greatly interfere with the functioning of the heating system. There are various European pellet quality standards currently in operation. Some of the more common standards are:
Austria: ÖNORM M1735
Sweden: SS 187120 and SS 187121
Germany: DIN 51731
Europe: CEN TS 14961
In Canada and the US the equivalent standard is Premium grade.

Labels: Energy