Return Pipe - Loud Banging / Water Hammer

Giants9890

*12/31 - Photo's Added of boiler, return to boiler, and problem area.

12/30: Original Post

Hi Everyone, thank you in advance for any help offered. I am a homeowner with three years under my belt, so I am a newbie when it comes to steam heat. I did my best to simply describe my issue--I hope this is enough to go on for now. (this is my first post to this website)

My equipment: Crown boiler, steam heat, one pipe system, three floor home (not including basement), home built in 1893.

My problem: loud banging from a collision of cold and hot in my basement return pipe.

When my boiler is fired, an area in the final third of my return pipe almost immediately gets very hot, and collides with the cool water flowing down the return pipe causing constant, loud banging. The area in question is near to the boiler and is right below a steam main. It is almost as if steam, or very hot water is forced downward to the return pipe.

A plumber came recently to diagnose the issue. He replaced some steam main/return pipe valves in the basement (I'm not certain of the exact part name) and ran water through the return pipe which deposited a good amount of 'mud' into a bucket. The job is certainly not finished as this has not stopped the banging in the area. I am being told the crew will be returning to give a quote to replace an area of the return pipe, valves, etc.

The radiators above seem to be working fine, though the room in the middle floor is cooler and I assume the radiator is underperforming.

What can I do? I can post pictures and/or videos if helpful.

Thank you,
Tom

mattmia2

we're going to need to see some pictures but usually this happens when someone replaces a boiler and the new boiler has a lower water line than the old boiler and the connection of 2 returns to the return to the boiler that was below the water line is on longer below the water line and there is no longer a water seal between those returns and steam can flow from one pipe to the other and get someplace it shouldn't be.

pressure that is too high can do it too

Derheatmeister

Make sure that all of the piping has a pitch so that all of the condensate can drain back to the boiler...If Steam hits a puddle of water/condensate due to a sag in the pipe it can cause a waterhammer. Any Rads replaced in the last couple years ? Pictures may help.

Giants9890

I posted some pictures. That same area in the return pipe had a leak, probably from the pressure of the water hammer.

Jamie Hall

Giants9890 said:

I posted some pictures. That same area in the return pipe had a leak, probably from the pressure of the water hammer.

You did? Don't see them...

KC_Jones

Banging is steam picking up water and slamming it into the nearest fitting.  It’s not really a temperature related thing.

It appears that you have a return pipe that gradually crosses the boiler water line and those can be problematic.  The horizontal pipes should either be well above the water line, or well below.  The pipes that cross the level of the boiler water line should be vertical to prevent what you are encountering.

So an over head return pipe should, roughly speaking, be slightly lower than the steam main, when it drops to be a wet return that drop should always be vertical and go basically to the floor until it gets back to the boiler.

If the new pipes are the ones in the wall, relatively low, with the gradual slope, I’d suggest the person you have working on this does not understand what they are doing as they look wrong.

You’d need to measure to be sure.  Measure the height of the boiler water line to the floor.  You want any “dry” return pipe to be at least 28” above the boiler water line.  All the wet returns should be well below the water line, basically at floor level.

Just because a pipe was there, doesn’t mean it’s correct.  Many times the original boilers were much taller, with a much higher water line, once that changes all the piping needs to be looked at.

Also, it looks like the steam piping on the boiler is incorrect, but we’d need a few more pics to know for sure.

Giants9890

Jamie Hall said:

Giants9890 said:

I posted some pictures. That same area in the return pipe had a leak, probably from the pressure of the water hammer.

You did? Don't see them...

I added in the original post.