The home owner had gone to the doctors as was feeling unwell. After a blood test it was shown to have Co (Carbon Monoxide) levels in their blood stream. This alerted them to have all the appliances tested in the home. The boiler is a Glowworm Ultracom 38cxi combi boiler. The home owner never had the boiler serviced since it was fitted about 10 years ago. Very Lucky escape!!
The boiler was repaired and a complete service carried out.