What is the best value for money flue gas analyser I have seen a TPI 712 analyser for £487.49 with infra-red/bluetooth output and deferential pressures, differential temperature and flammable gas detection?
You can block the base of the chimney, fill with vermiculite insulation and cap the top of the chimney this method stops the heat going up the chimney and as there is no air in the chimney it won't need venting
electrics should be done by part p electrician as it is an extension to the wiring :D