OK, without trying to get into a heated argument, (RCD's in the application in question) The regulations can be quite confusing, they are not a legal requirement, only guidelines for recommendation. so I would like to clarify something, which is, that whilst it is preferable for all circuits to be protected by an RCD it is not written in stone that they have to be, you have to consider the practical applications of the installation, so in my view, the exemptions to this are Freezers, Smoke Alarms & Boilers because all could be adversly effected by being on an RCD circuit, which again is why there are now High Integrity Consumer Units on the market to allow for this. however, having said that, there is nothing wrong with connecting to an RCD if so desired, you just have to accept the consequences of the end result, i.e smoke alarms not going off in the event of a fire were the batteries to fail, loss of food stuff if the freezer went off whilst away due to the fault of another circuit or burst pipes because the heating went off for the same reason. something to think about!
If I were to do the job for DESROB who asked the question on this, then I would suggest creating a new circuit, supplied by a non RCD protected CB as they are now known (Formerly MCB) of the appropriate size which is dictated by the boiler and cable size and then connect to a local 13amp fused spur, again with the appropriate fuse fitted.