pipes banging and water coming out of vents

Snowmelt

went to a service call this morning , home is under construction , there where three rads moved. one was banging and water came out of the vent. I see it was moved from one location to another, there was a slight pitch going the wrong way and the rad was perfectly level. I pitched the rad and bang stopped a little other rad had a lot of water coming out of rad but that was level also. I pitched the rad to go back towards the boiler , it slowed down the water, no banging came from the rad. the air vents looked old and original, could they just be bad from time. near boiler piping was done at a minimum but still looked good, sight glass was NOT jumping but a little dirty. third rad was working just fine. my question is , if the rad is dead even with no pitch would it still bang.

Danny Scully

Well you pitched both rads and stopped the banging correct? So you answered your own question How big of a level did you use to confirm? Really you need a torpedo level to check section by section. What I’m getting at is that maybe the rad wasn’t in fact level the entire way across. The only rads I leave dead level are recessed cast iron radiators, because if you pitch them (on a one pipe system) you’re actually back pitching the supply. And yes, the vents could just be bad at this point. They have a lifespan and eventually require replacement.

the_donut

Pressure issues? Changing vent won't hurt but my experience is water is from obstructed valve. Was valve closed?

Fred

Check system pressure and make sure it is set correctly and that the pigtail isn't clogged.
Also make sure the supply pipe is sized correctly for the radiator(s).

Snowmelt

Thanks for listening, I was called to the job by a plumber who only likes to do rough ins. I pretty much told him every thing but the make sure pigtail is clean and pressure is corrrect. I will go there at the end of week to see if he fixed the pitches.