38 CXi with thermostat problem ?!?

I have a 38 CXi and all has been working well, but it was moved recently due to house extension work. Now, irrespective of whether the central heating is on or not, the boiler will kick in regularly. I suspect that it is monitoring the temperature and the anti-freeze is working, but it can be on all day / night. Can the anti-freeze setting be wrong / faulty - can it be adjusted?