Trouble with your heater or cavity wall? The worst noises often occur when pipes are laid in shallow notches cut in the floor joists, and the floorboards are screwed down tightly on top of them. The traditional way to prevent this was to wrap the pipes in felt where they passed through the notch; a more modern solution is to use polypropylene pipe-joist clips from Pegler Yorkshire Fittings, which have the additional benefit of strengthening the notches. Where pipes run parallel to the floor joists, they should be fixed with plastic clips rather than metal ones, at the manufacturer's recommended spacings. Finally, you could lessen the amount of expansion and contraction by running your boiler at a constant low temperature - as recommended regularly in this column - rather than having it constantly cycling on and off from very hot to cold again. Q: I am wondering how much it would cost to have cavity wall insulation (mineral wool fibre) removed from my semi-detached bungalow. It has made it damp and all the windows are wet every morning. I am a pensioner and wondered if the Government would contribute to this. EN, Sunderland A: Most cavity wall insulation victims do eventually succeed in getting it removed by the installing company. Don't expect them to give in without a fight, though. They will insist that cavity wall insulation cannot cause dampness, and that your problems must therefore be self inflicted, due to "lifestyle condensation." They will then tell you that your walls need repointing and/or waterproofing. You should resist paying for any extra work of this nature, which will be ineffective. Your local authority environmental health department might be able to help you, by putting more pressure on the installing company. You will not get any government assistance though, because the Government - through its quango the Energy Saving Trust - is still trying to persuade yet more householders to have cavity wall insulation installed. If the Government were to finance the removal of existing insulation it would first have to admit that retrofit cavity wall insulation is actually not a good idea. Q: With reference to your comments on British Gas service engineers (January 8) how can I find a reputable local gas service engineer? LS, Leicestershire A: Independent local heating engineers can be found from the Gas Safe Register, by calling 0800 408 5500 or at gassaferegister.co.uk - where you can find engineers by typing your postcode into a search box. I suggest you call a number of firms in your area and sound them out. Tell them you are interested in an annual boiler service, and someone reliable you can call in an emergency. Some small firms charge a modest retainer for this service; others provide it as a matter of course for their regular customers.