Slurping and odd sounds on closest steam radiator to boiler, banging not an issue

Joshmarc77

I have a one-pipe steam system in a 1920 house in the Boston area. I have replaced all the radiator vents with Hoffman adjustables and balanced according to distance from the boiler. My pressuretrol is set at 0.5 psi with a diff 1 psi. The boiler is running at 2.5 pounds which is an improvement from 4 psi, before I replaced the steam vents. The boiler supplies the first floor apartment, with 6 radiators. The boiler is about 15 years old, and has a copper expansion tank on the outlet steam header.



My issue is in my bedroom, the radiator which is closest to the bolier, makes this odd slurping noise upon initial cause for heat. It's almost like the vent is breathing in and out it sounds like water sloshing back and forth. This radiator is probably half the distance to the next radiator in the bathroom and about 1/10th the distane to the further radiator. The boiler level is good. This sloshing is very annoying and lasts for about 5 minutes on initial call for heat. A sparkly noise (best I can describe occurs), almost a million little droplets hitting the radiator. Wet steam?? Not sure how to check or control that. I have yet to have a heating professional take a look. I have some basic understanding of steam. All I can guess is that the steam is condensing on the cold iron and becoming water and that water is sloshing around some how due to a fluctuation in pressure. Any help or suggestions is appreciated.

Jamie Hall

That sort of noise

is very often caused by water -- condensate -- lying in a steam main or the runout to the radiator affected.  It may not cause a water hammer, but the water makes the incoming steam collapse, forming a bit of a vacuum and sucking air in at the vent, then the stearm comes on a little more and so on.  Check all your mains and runouts for correct pitch for starters.



I'm curious about the "expansion tank" -- what on earth might that be for?  And I wonder if there might be condensate in there causing the problem...



Also, how are you judging the system pressure? 2.5 psi is still too high, and higher than it should be with the pressuretrol set as you describe it.  However, if that is based on reading one of the 0 to 30 psi gauges...

Joshmarc77

Thx for the reply....

I'm not sure of the purpose of the expansion tank, or maybe more a chamber. My friend recently had new steam boilers put in and they removed his similar expansion tank. It is about ten inches tall and maby 8 inches round, a cylnder, mounting vertically on the steam outlet.



The pressure is 2.5 # on the 0-30 psi scale of the gage on the boiler. There is a slight pitch on the pipe similar to the other radiators. There is a 90 bend with a pitch.



Your idea of the water causing incoming steam to collapse makes sense. Is it possible since its the closest radiator water could have fouled the pipes due to overfilling in years past (I got the house 1.5 yrs ago) and has caused the condesate flow back to be hindered and thus the steam collapse?



Also, how can I lower the pressure when I'm at minimum on the pressuretrol, perhaps I need a full servicing of the boiler?

Joshmarc77

Thx for the reply....

I'm not sure of the purpose of the expansion tank, or maybe more a chamber. My friend recently had new steam boilers put in and they removed his similar expansion tank. It is about ten inches tall and maby 8 inches round, a cylnder, mounting vertically on the steam outlet.



The pressure is 2.5 # on the 0-30 psi scale of the gage on the boiler. There is a slight pitch on the pipe similar to the other radiators. There is a 90 bend with a pitch.



Your idea of the water causing incoming steam to collapse makes sense. Is it possible since its the closest radiator water could have fouled the pipes due to overfilling in years past (I got the house 1.5 yrs ago) and has caused the condesate flow back to be hindered and thus the steam collapse?



Also, how can I lower the pressure when I'm at minimum on the pressuretrol, perhaps I need a full servicing of the boiler?

BobC

An old fix

That sort of setup was used back when the first "modern" steam boilers were being installed, I think they were trying to create a larger steam chest to compensate for modern boilers lack of same.



Check this problem radiator and the pipe feeding it to make sure everything is sloped to allow any water to flow back to the boiler. is this a single pipe steam system?



Post some pictures of the boiler, the pipes around the boiler , the pipe feeding this radiator and anything else you think might be pertinent.



Bob

Joshmarc77

Thx Bob

I unfortunately sans camera phone for a few days. I can say the pipe is at slight pitch, but I just took another look and there is a spot coming out of the first floor where the pitch approaches 0 degrees for about a foot. I think it was caused by a piece of wood used to brace the pipe and a second floor pipe, and maybe over the years caused a loss of pitch.



Should I try to adding a piece of wood further up to try to recreate the pitch?

BobC

Worth a try

You mighty try a shim under the vent side of the radiator if you suspect it might not have enough pitch. If your trying to correct for something further down shim both ends of the radiator up with 1/2" or 3/4" blocks. use a lever and a block to GENTLY lift the radiator, we don't want to break anything. radiators are heavy, try to get some help.



Don't trust your eye, use a level.



Bob