Heat output tests – six fuels on three appliances
Back in February Defra published their response on their cleaner domestic burning of solid fuels and wood consultation. In conjunction with the announcement was a BSRIA report commissioned by HETAS (on behalf of Defra). The report identifies the useful heat output of a series of solid fuels selected from typical fuels available to the public.
The summary of this report should be read in conjunction with Defra consultation response, which was summarised by HETAS back in February.
The research found significant regional variation in prices but that manufactured solid fuels are in fact cheaper to burn on an energy density basis. Government understands that it is important that householders are provided with this information and supported in making a change which may save them money over the longer term.
There had been concerns about the comparative costs of burning house-coal, a less expensive fuel per kg vs smokeless fuels and whether there was an issue for fuel poor customers? The report shows that the cost of using smokeless fuels versus house-coal and expresses this as “Average £/useful kWh output”. The report shows that for both varieties of Manufactured Smokeless fuel (MF1 and MF2) the cost per useful kWh which can displace the use of house-coal in open fires, are slightly more cost effective for the user.
There were similar concerns about the cost of buying and burning wetter wood fuel versus processed (seasoned, kiln dried or briquetted wood fuel. The report uses the same measures as in (1) above and demonstrates that the useful heat output of dry wood exceeds that of wet wood due to the moisture contained in the fuel. Again, the usual extra cost of buying dryer wood fuel is countered by the increase in Average £/useful kWh output.
Note; there may be a period of time during transition where the user has to learn to vary the refuel load using less smokeless fuel or dry wood than they were used to when burning house-coal or wetter wood fuel.
The report details a bespoke test procedure covering tests carried out on three different appliance types to identify the useful heat output of a series of solid fuels. The results of the testing were then used to calculate the costs associated with operating each appliance type with each fuel type across five pre-defined regions in England. The general test procedures and practices set out in the standards listed in Section 6 were followed where relevant with deviations as noted to enable a practical application in achieving the objectives. Testing was carried out on the BSRIA solid fuel appliance test rig in Bracknell, Berkshire during March, April and May 2019.
The objectives of testing were to assess the heat output, and subsequent regional cost/useful kWh output from three solid fuel appliances consisting of an open fire, an old stove, and a modern Eco-design ready Clean Air Act compliant stove, using the following fuels:
- Bituminous house coal
- Smokeless manufactured solid fuel (MF 1) which meets 2% sulphur and 5g/hr smoke test
- Smokeless low cost manufactured solid fuel (MF 2) which meets 2% sulphur and 5g/hr smoke test
- Kiln dried wood (<20% moisture content)
- Seasoned wood (<25% moisture content)
- Wet wood (>30% moisture content}
- Wet wood (>40% moisture content)
Costings for the fuels listed above were to be researched in both bag and bulk quantities across the five following pre-defined regions in England:
- North East
- North West
- South East – including East of England
- South West
To view the full BSRIA report, Summary of responses and government response, visit the Defra website.