Perhaps if you've already done that and it still overheats, the boiler is furring up with limescale inside allowing too much pressure to build up when the house is up to temperature and hence some TRVs are closed. So it could be in need of a defurring (if such a thing is possible)?
Although this is where my knowledge of such matters swiftly declines.
Perhaps if you've already done that and it still overheats, the boiler is furring up with limescale inside allowing too much pressure to build up when the house is up to temperature and hence some TRVs are closed. So it could be in need of a defurring (if such a thing is possible)?
Although this is where my knowledge of such matters swiftly declines.