Why is my boiler making a banging noise? Here is the honest version: what you can safely check yourself in the next five minutes, what a technician usually finds when it is not that, and exactly what it costs to find out.
By Full Swing Plumbing Heating & Cooling, Greater Boston, MA. Updated September 27, 2026. Rated 4.9 out of 5 across 874 reviews.
If one of these fixes it, you owe us nothing and we are glad. If not, the next part is what the visit is for.
Noise. Popping and percolating in the sections is water boiling against scale: mineral deposits laid down by makeup water, or water whose pH has drifted. The water sits long enough to boil because it is not moving: valves not fully open, or a circulator too small for the loop.
Cold radiators. A radiator that stays cold while the rest heat has air trapped in it, or the system pressure is too low to lift water that far. Air keeps coming back because water keeps going out: the manual sends the technician looking for the leak whenever the pressure is low.
These are the causes in the manufacturers' troubleshooting charts and the trade handbooks our technicians train on, in plain words. The visit proves which one it is with a meter before anything is replaced.
A combination fill valve and backflow preventer meters the makeup water and keeps the loop from refilling with fresh oxygen and minerals, which is what the manual says wears the sections.
A combination fill valve and backflow preventer meters the makeup water and keeps the loop from refilling with fresh oxygen and minerals, which is what the manual says wears the sections.
$59 on weekdays, $159 evenings and weekends. Published and final, pre-tax, and the price is the price whether we find a loose wire or a bad motor.
Book the $59 visit online Or call (781) 424-0700Real arrival windows, including evenings and weekends. Paying is what confirms the slot; the office calls to confirm the window.