Anyone who has had a central heating breakdown in the last few weeks will know how difficult it is to get a decent engineer round to fix it, I was out late every day last week, the earliest finish was 7pm, the latest was 10pm, this is because people turn the heating off completely for around 3 months, and expect it to work when they switch back on, well, you wouldnt park your car for 3 months and expect it to start would you!
So, in summer, turn down the room thermostat, if you dont have one, turn down the boiler thermostat, this means the heating will start all the moving parts regularly, and not actually generate any heat, and there is more chance that it will start up when you turn the heating back up in the wintertime, and every man and his dog wont be ringing at the same time wanting assistance!
And will save you time, trouble and expense!