January 22nd 2009. A CO {Carbon Monoxide} alarm had gone off in a private residence in South Liverpool. It was sited outside of a compartment, on the first floor landing, which housed the central heating boiler. Adjacent to this cupboard were four bedrooms. Directly above it the loft had been converted into a fifth bedroom. All rooms were occupied.
The householder rang Transco to report the incident. Their engineer duly arrived, isolated the boiler and attached a warning notice. He advised the householder to call a C.O.R.G.I. registered gas installer to check the boiler. I received that call at about 10.00pm that evening and arranged to visit the property the following day.
Upon arrival we first looked at the generally installation of the appliance. The boiler was a room sealed model with an extended flue system. The flue rose vertically up into what had previously been the loft. It had originally terminated at roof level. When the loft had been converted the flue had been rerouted beneath the new floor of the loft conversion to terminate horizontally to the rear elevation of the property. This work had been carried out by unregistered installers. The flue terminal was now passing through the timber soffit and touching the plastic gutter. The minimum distance it should have been from the timber soffit was 200mm. The minimum distance it should have been from the plastic gutter was 75mm.
Next we looked to see if there was any service history with the appliance. The householder said it was last serviced three years previously. The service engineer hadn’t noted the incorrectly routed flue and terminal which suggests he wasn’t very thorough. We noticed some staining around the flue hood of the appliance suggesting leakage of combustion products.
We reinstated the gas supply to the boiler, restarted it and carried out an ambient CO test in accordance with British Standard 7967 using our flue gas analyser {pictured above} taking readings from around the compartment area. Within less than two minutes the gas analyser was warning us of high levels of CO in the atmosphere at above 50 ppm {part per million}. These products of combustion were escaping from a perished gasket joint on the flue hood of the boiler, where we had noted staining. This is what had triggered the householders audible CO alarm.
The manufacturers servicing instruction of the appliance clearly stated that 3 gaskets needed to be changed during a service. This hadn’t been done. The price of the gaskets was just £12.00.
Readings taken from the appliance sample point showed it was producing potentially deadly levels of CO of 9874 parts per million {PPM}.
At 6400ppm severe medical symptoms can occur within 1 – 2 minutes and fatal consequences within 15 minutes. At 12800ppm immediate medical symptoms and fatal consequences can occur within 1 – 3 minutes. This appliance was mid way between the two. The industry category would be IMMEDIATELY DANGEROUS.
As well as being very dirty due to lack of regular servicing the appliance had a damaged burner. This coupled with the incorrectly installed flue convinced the householder to replace it with a modern equivalent high efficiency appliance.
Correct controls on central heating systems are vital. Everyday we see systems with inadequate or incorrect controls which do not conform to the building regulations. Gas and oil which are the main fuels for heating systems are expensive. Incorrect or inadequate controls mean increased fuel bills.
