School heating options

As students, most of us were oblivious to the source of heating in our schools. All we knew was that hot radiators or hot air were present in the classroom. In most cases this type for heating was supplied by burning coal, gas or oil. A few of the more modern and smaller schools used electrical heating. This is a cheaper option to install but will most certainly be a more expensive system to run.

With the introduction of heat pumps (air conditioning), many schools have upgraded existing heat plant to these highly efficient heating and cooling systems. Unfortunately the increase in electrical heating is putting a strain on the supply network and most schools were not setup for intensive use of electricity. With individual heating systems in each classroom, there is less control of the heating source (electricity).

For schools that still have the original heat plant setup of a boiler and hot water heating network, there is an environmentally sound option for using this plant. These boilers can be converted or replaced to run on wood chips or wood pellets, which are carbon-neutral fuels.

Converting from fossil fuels to wood-fired boilers

Existing coal boilers are very suitable for a fuel swap to wood pellets. The main fuel feed and existing grate are similar to a modern wood pellet boiler. The main requirement in a conversion is to build a steel fuel bunker and feed system to reduce any man-handling of the fuel. Once the fuel is delivered to the boiler, the combustion characteristics must be changed to burn the wood pellets effectively and efficiently. In most cases this requires the installation of over-fire air.

Once the combustion side is tuned the existing control panel with time clocks is removed and a modern Programmable Logic Controller PLC [MA1] is installed to increase the flexibility of the system. This also allows safety options such as temperature probes to detect and contain burn back.

Gas and oil boilers are simpler in design and therefore require a different approach for conversion. The gas or oil combustion head can now be swapped for a wood pellet burning head that accomplishes the same output. The main consideration when changing from a liquid or gas fuel to a solid fuel is the requirement for fuel storage. If undercover storage is available then a bunker can be installed. External fuel bunkers are also an option if space is limited. For boilers that are at the end of their service life, a complete replacement boiler may be an option. With a replacement boiler the existing heat transfer medium (hot water) is still in use. This reduces the capital expense of changing heating systems. Once the piping network is removed and heat pumps are introduced there is almost no chance of returning to the original heating system in the future.

Environmental impact

All combustion releases emissions into the environment. The benefit of changing to a biomass-based fuel, such as wood chip or wood pellets, is that the carbon released during combustion has already been accounted for in the growth of the tree. These fuels are known to be carbon neutral and sustainable, when they come from responsibly-managed forests. For schools that have an environmental focus, this is the best option. Other reductions in emissions are CO (carbon monoxide) and SO2 (sulphur dioxide). For conversions from coal to wood pellets the particulates count has been halved.

Other health issues relate to the handling of coal by the caretaker. This day-to-day contact with the coal dust can have serious effects on the health of the caretaker. Once combustion is complete the ash created by burning wood is able to be removed and placed on the garden as a soil conditioner. The ash produced by combustion is also reduced to 10% of what is produced in a coal boiler. The formation of clinker is also reduced and once the boiler is tuned well, clinker will be a thing of the past.

Contact details for suppliers

Ernslaw Bio-Energy
Contact: Murray Cowan
Office: 021 393 141 Sales: 03 444 9971
Email: info@ernslawbioenergy.co.nz

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Fogarty Industries Boiler Manufacture
139 Crinan St
Invercargill NZ
Email: johnfog@southnet.co.nz
Ph: +64 3 2144316
Fax: +64 3 2144315
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"HotShottzz" from Golden Strand Wood Fibre Products Limited - Auckland
PO Box 71-091, Rosebank, Auckland
Telephone: 64 (0)9 828 4859
info@pineshavings.co.nz
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Inset Firelogs (NZ) Limited
Contact: Duncan Wattie
Manchester Street, Flaxmere, Hastings
PO BOX 2401, Stortford Lodge, Hastings
Tel: 64 (0)6 879 8151
Fax: 64 (0)6 879 8151
Mobile: (025) 628 7891
firelog@xtra.co.nz

Living Energy Ltd
Contact: Rob Mallinson
Main Office: Auckland Business Centre, 6 Clayton St, Newmarket, Auckland
Postal Address: PO Box 125195, St. Heliers,Auckland, 1740
Office :  64 (0)9 377-9007
Mobile : 64 (0)27 257-9001
info@livingenergy.co.nz
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Nature’s Flame - Christchurch and Rotorua
Christchurch showroom at Hoskins Road, Rolleston
Freephone: 0800 PELLET (0800 735 538)
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Wood Pellet Fuels Limited
Contact: Bruce Clow
364 Lumsden Rd, Ohinewai, Huntly
Freephone: 0800 4 PELLETS
Tel: 64 (0)7 826 4033 or 64 (0)7 826 4040
Fax: 64 (0)9 236 0057
brucec@pelletfire.co.nz
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Southern Wood Pellets
Contact: Aven Erskine
207 Branxholme-Makarewa Rd,
Branxholme, Invercargill
Tel: 64 (0)3 235 8424

Spark Energy Limited
Contact: Eduard Ebbinge         
Email eduard@sparkenergy.co.nz
P.O. Box 32-283,
Devonport,
Auckland 0744,
New Zealand
Tel: +64 21 766 110

The Green Lucifer Company - Auckland
Christchurch - coming soon
Tel: 0800 451081
Tel: 64 (0)9 889 0971
info@greenlucifer.co.nz
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