Peerless Boiler makes a large boom

[Anonymous]

I have a Peerless natural gas boiler the very intermittently when it lights makes a large boom.

[stanhvac1]

Can you smell raw gas prior to ignition? You could have a leaking gas valve allowing excess gas build up in combustion chamber, a cracked heat exchanger or an improperly adjusted ignition/air mixture. In either case you need to have it checked by a technican trained in gas burners unless you have the knowledge required to repair the system.