Banging Boiler

[oilman52]

gas fired boiler banging..my sister-in-law lives in NYC and I'm in Ma. Already told her to check for pipes hitting anything. Boiler is one zone and bangs 2 or 3 times a day. Had a tech. from where she is look at it. One said "I don't know". The other one changed out HSI. Hard to explain to her what delayed ignition is. I asked her to look at PSI,all this over the phone,it was only 10psi. I had her pick up on water feed to see if water could pass thru,it did. Water feed valve(quick fill,whatever you want to call it)is bad. It will let water in but only manually. Would the pressure loss be a source of the banging?

[Dof3]

oilman,if it is low on water it will bang. If it is a copper boiler it will flash and make steam,this makes a hell of a racket.

[hot wired]

try checking the high limit on boiler maybe it is bad causing temp to go above 180 or 200 degrees causing water bang which is when steam hits water.

[MikeJ]

Single story, two story house?
Expansion tank checked?
10psi seems a bit low. Radiators bled recently?

[git-r-dun]

I agree with everyones input, water hammer is probably due to low water or overheating. If water pressure regulator is not making up water it should definately be replaced.