fourth year
The pump is a water moving device, it does not change to total pressure of the system. If the pressure is normal when the system is cool and high when it is hot, then you do not have enough air in the system, notably in the compression tank as opposed to a comment that you have too much air. Air, being compressible, is used as a moderating medium in heating systems to keep the pressure from making large changes as the water is heated. Your pressure reducing feed valve may have lost its adjustment, in which case you can back the adjusting screw out a little, or it may need to be replaced.
