Banging Hartford Loop
Hello to all. Has anyone actually encountered a banging Hartford loop ? All of us here were taught about the importance of a short nipple on the Hartford loop. I do strictly residential work and I have seen endless Hartford loops, with nipples of all sizes and lengths. I have never ever encountered a Hartford loop that had any banging noise. On one of the more recent boiler installations that I did, I deliberately installed an excessively long Hartford loop nipple. It was a mixture of convenience and experimentation. It was something like 18 to 24 inches. Not a sound. Zero banging in the Hartford loop or anywhere else for that matter. Would love to hear about everyone else's experiences.
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I have not, and I have not been able to understand how the short nipple matters since the whole thing is submerged anyway.
The wet return has a very long horizontal also
NJ Steam Homeowner.
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Not really sure. Maybe under extreme circumstances, such as a boiler with water that is boiling violently, steam bubbles can get forced into the Hartford loop nipple. Steam bubbles would never end up in the wet return, because steam bubbles will not go down in water. They will go horizontally or up. A longer Hartford loop nipple, means more room for those steam bubbles to congregate. The More Steam in that nipple, the increased likelihood of banging. Not really sure if this thought process holds water (pun intended).
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The HL is usually 2-4" below the normal water line so it should be submerged unless your low on water.
Probably if you ran with the water level lower you could get banging as you would then get steam and water in the horizontal nipple.. The reason for a close nipple is to minimize the banging in the horizontal which is where the banging would take place.
We all know many of the old boilers had 1 return in the back 1 supply out the top no header and no equalizer and no Hartford loop and worked fine. Things evolve over time.
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the way i see it the only way the equalizer won't be filled with air so steam can't even get down there is if the equalizer has to actually let steam in to the return to equalize the pressure between the supply and return.
on a 1 pipe system, unless it is piped very wrong or there is some sort of false water line or something, the supply and return are connected together somewhere so there can't be much of a pressure differential, so on a 1 pipe system the steam can't even get down there.
on a 2 pipe system it is possible to get enough differential that steam pushes down the equalizer so you could maybe get water hammer there but it would be the same situation with a boiler return trap or with the close nipple. i don't see where the surface in the nipple is significant compared to pushing the whole loop of water out of the way.
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oh so you think the water very near the boiler is still hot enough to be boiling. i kind of think the temp of the water falls off rapidly as you get away from the boiler block but it is an interesting theory.
you could try heavily insulating the equalizer and hartford loop and see if that would make it bang.
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Steam goes down the equalizer until it hits water. The air rises up and goes out with the supply steam. If the equalizer stayed full of air it would be cooler and they are always steam hot.
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Mine has given a few pings recently when water level was pathologically low (carryover issue) but otherwise no. I did suggest the installer go with a close nipple and bring the condensate in from below ( he had other ideas). Vacuum also seems to be involved.
Steward to 1923 Spanish revival near Chicago - 2 pipe steam 650 EDR shiny new Peerless 63-06
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Mine stays pretty cool, I'll have to double check it. I think on a normal call for heat there isn't enough time for the steam to mix with/replace the cool air down there.
NJ Steam Homeowner.
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It's hard to imagine that steam goes down The equalizer. The equalizer is unvented. It would seem like it's pretty much impossible for steam to get past the last main takeoff. A hot equalizer is probably because there is hot water going down the equalizer. And maybe there is steam going up the equalizer
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i was going to suggest the same, that it was the condensate and carryover from the header that was heating it.
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Either way. On a cold start there is air in the equalizer. Steam comes in the header some condenses and rolls down into the equalizer. The only place for the air to go is back into the header and out into the supply pipe.
I hope no one thinks the air that is in the equalizer when the boiler is installed and filled with water stays there for 100 years.
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Hey there @STEAM DOCTOR is there an obstruction, or a partial obstruction in the piping?
This one's a head scratcher.
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true but the amount of condensate is very tiny. It doesn’t replace the air, it flows past it as a skin against the pipe. The air stays more than it goes I feel
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
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You already have temperature sensors.
Feel the equalizer all over and see where it's steam hot and not.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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isn't the water in the boiler going to be really close to the temp of the steam so they will feel the same?
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Yes but the return water isn't.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Not 100% sure that I understand the question. There is an obstruction in The equalizer, and in the header piping beyond the last takeoff, that will block the steam. And that obstruction is air. Steam and air don't mix
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I'm hazarding a guess here… How long has this been going on? Is water chemistry used? Is there sludge buildup or even metal flakes acting as a check valve?
Had a similar issue on a light commercial boiler years ago. Did a lot of blow down and boiler cleaning/ chemical use. This seemed to quiet the boiler hammering some.
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