Water Hammer (?) during cool-down

Al Letellier_9

You didn't indicate what you did to eliminate most of the hammering so far, but with a single pipe system, the problems are usually limited to venting, pitch of piping and radiators and partially clogged returns. There isn't a lot left. Is the pressure set low? Have you checked all of the above? Is the water clean and properly adjusted for PH?
Are the mains insulated? All of these are things I would check first. It is unusual that something "exotic" could be happening to your system. Hard to guess anything else without "eyes on" diagnostics.....get a pro to look at it.

Chris R.

Water Hammer (?) on cool-down

After lots of reading and lots of work, I have been able to eliminate most of the water hammer in my 1-pipe steam heating system. It now heats up and runs perfectly quiet. But that was just to lull me into a false sense of security. Now I'm getting bangs from the radiators 30-60 minutes AFTER the boiler stops firing! This has me completely stumped. The radiators are cooling off at that point and are only mildly warm to the touch. The bang goes around the house like a game of musical chairs, jumping from radiator to radiator every minute or two. Does anybody have an idea on this?
Thanks,
-Chris R.

Chris R.

Well, so far I have insulated all the steam pipes, leveled all the radiators, relaced all the air vents, flushed the dry & wet returns, skimmed the boiler, reduced the pressutrol to 2.5/1.5 lbs, made sure all the radiator valves were fully open. That eliminated all but this cool-down banging. What else should I try?

Al Letellier_9

banging

Reduce the pressure as low as it will go. Assuming you have a Honeywell pressuretrol, set the cut in at the bottom of the scale and the differential wheel at 1. See if that does the trick. What did you use for radiator vents and do you have vents at the ends of the mains?

Chris R.

Banging

The vents are NO. 1 Vent-rite and adjustable with a plastic wheel #1-8. I have them set btw 5-7. The vent at the end of the main is also new. I will try reducing the pressure as low as it will go! Thanks!

SusanC

the phantom in the radiator

This year I have this also; on warm days when the burner is off for a long time, it can happen even 1 1/2 hrs after the cycle. Also happens when burner has just started firing.
It's at the radiator location, not down at the Hartford Loop. I mention that because a while ago in this forum someone said if the H.L. is too high, you can get a snapping sound after the heat cycle is over.

I notice the sound I get from these 2 radiators is not the real resounding pipe banging sound of a full-fledged water hammer - could almost be described as snapping. I'm thinking it's more like some expansion and contraction of metal. The 2 radiators in question are in enclosures which also make some of their sounds; I don't think all the sounds are from these; someday I will remove an enclosure and see what happens. In the meantime I will relax and enjoy my steam symphony in which percussion is by far not the only component.

Steamhead (in transit)

That does sound like expansion

try pulling the covers and see if that helps. I'd leave them off, the usual design reduces the radiator's output by about 33%- and guess what that does to your fuel bills?

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