Christine Goodall died of multiple injuries when the cast iron boiler behind her fireplace burst, causing burning wood and shrapnel to rain down on her, an inquest into her death heard.
The 65 year-old woman had been told the open fire in her Twyning home was safe to use when the boiler was put out of service in 1999. However, after lighting her fireplace on November 11, 2007 for the first time since the boiler was put out of service, the boiler heated up and exploded.
The boiler had not been fitted with a venting valve and the residual water expanded to bursting point, the coroner at the inquest heard. The back boiler was decommissioned by Matthew Lee in 1999, for a contract from Severn Vale Housing.
On Thursday, October 29, before recording a narrative verdict, Gloucestershire coroner Alan Crickmore said inadequate guidelines provided by Severn Vale, and heating engineer Matthew Lee's lack of understanding, left Mrs Goodall at risk.
Laurence Aston, contracts manager at Severn Vale Housing Association, told the inquest at Shire Hall, Gloucester, he was happy with work completed in the past by M & T Plumbing. He said although the work completed at the retired woman's home was not inspected, this was not unusual as only a selection of homes were visited.
Last May, the HSE issued a safety alert for homeowners, tenants, landlords and the plumbing/heating industry to highlight the potential dangers of lighting a solid fuel fire when a redundant solid fuel back boiler has been left within the fireplace. When a fire is lit in front of a redundant back boiler, left in a sealed condition, it can heat up and the internal pressure can cause the boiler casing to explode.
In its safety alert, the HSE stated "Previous advice recommended that a redundant back boiler left in situ must be in a condition such that an unsafe level of pressure cannot build up in the unit. Thus, at the decommissioning stage the system should have been drained and redundant pipework removed along with, ideally, the back boiler itself. If not removed the boiler should have been left in a 'vented' or 'open' condition. If the pipe connections were plugged, at least one 6mm diameter hole should have been drilled in the water jacket, preferably in a vertical or near vertical face.
"In some cases, the decommissioning may have been carried out by an individual, or heating or building organisations that were unaware of the potential problem, or had not seen the advice".
Since the explosion, Severn Vale Housing Association has visited about 1,700 homes to make sure its residents are safe.
The housing association said in a statement "Severn Vale Housing Society offers its profound sympathy to the family of Mrs Goodall.
"We are very grateful for the tremendous amount of advice and support received from HETAS and the Health & Safety Executive in designing a solution to the problem which is also relevant in the national context.
"This type of back boiler was not only fitted in housing association and council homes, but also in thousands of owner-occupied properties across the country. There is consequently a significant public interest issue connected with the case".
A spokesman for HETAS, the independent UK body for the official approval of domestic solid fuels and solid fuel burning appliances, said "The only positively safe and reliable way to proceed, when a solid fuel back boiler is no longer needed and the customer wants to continue using the fireplace, is to totally remove the back boiler installation by breaking up the chamber that used to carry the hot water system and removing any pipe work. When an open fire is left in use (or could be brought back into use) a replacement Milner fire back needs to be installed to ensure that the fire can be safely used".
HETAS added "Similarly, a "wet" solid fuel room heater or stove with boiler should not be operated after the water supply to the boiler has been disconnected. These appliances are not designed to be used without water circulation".
In tests carried out in 2002, it was found that the top and sides of a solid fuel back boiler, without circulating water, reached temperatures in excess of 700°C. Within 2 hours the temperature in some areas had reached around 480°C. This compared with normal system maximum operating temperatures of 124 degrees Celsius.
Mrs Goodall leaves behind three sons and three grandchildren.