My home's heating system uses hot water baseboard. We had an old oil boiler running for many years. The system was getting old and started to have small problem and I decided to convert it to gas combi boiler.
However, right after the conversion, it sometimes makes single big bang noise when zone valves turn on. It happens randomly, and around 2~6 times a day. My plumber who install the new Bosch Greenstar 151 Combi boiler system couldn't figure out the reason.
The bigger problem is, I believe, this water hammer has lead to two failures on the boiler's pressure relief valve and leaked a lot of water in my basement.
Here is the diagram of my heating system:
I also capture a video showing the banging noise when the zone valve turns on. My in camera microphone may not do a good job capturing the big noise, but it is loud.
Can you help?