for those experts of the Hartford loop (2025)

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steamhouse Member Posts: 41

August 2017 in Strictly Steam

My understanding is that the Hartford loop needs to be 2 inches below the water line, and the Gifford loop is above the water line. My question is does it matter if you are any where in between?

unclejohn Member Posts: 1,833
August 2017

That would be the Giffhart loop.
5
steamhouse Member Posts: 41
August 2017

Perhaps someone can tell me why 2 inches below the borderline is stipulated in the instillation guide?
ChrisJ Member Posts: 16,132
August 2017

steamhouse said:
Perhaps someone can tell me why 2 inches below the borderline is stipulated in the instillation guide?
To keep the system from hammering in normal use. If that section of horizontal pipe is partially full steam can mix in with the water and cause hammering.
I would do as the rules say and either keep that area totally full or totally empty under normal conditions just to be safe. Doesn't mean it won't work, it just means it may not if you go in between.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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Charlie from wmass Member Posts: 4,357
September 2017

seldom is there a noticeable difference. The idea is for the water to return above the minimum safe water line yet still remain full of water during normal fluctuations in boiler water levels during a call for heat. If the loop is high as the boiler runs it will slowly become dry and it has a potenial to bang, seldom witnessed in the wild though. The higher inlet height will slow the return water, usually not perceptible in most smaller residential steam systems. Larger systems expand effects of mistakes sometimes seemingly exponentially.
Cost is what you spend , value is what you get.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
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steamhouse Member Posts: 41
September 2017
See Also
hartford loop 6" too low Steam Boiler: Does the installation of a "Hartford loop" matter?

My reason for asking is that I have a slow return and when steaming the loop is above the waterline. I feel like the loop being lower (2" below the normal waterline) would help in some regards.
Charlie from wmass Member Posts: 4,357
September 2017

no it will not. flushing the return will help. or replacing the return piping
Cost is what you spend , value is what you get.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
1
New England SteamWorks Member Posts: 1,521
September 2017

Charlie from wmass said:
no it will not.
Agree completely.
Other issues in play. Not this.
New England SteamWorks
Service, Installation, & Restoration of Steam Heating Systems
newenglandsteamworks.com
Charlie from wmass Member Posts: 4,357
September 2017

Normal water line is a height that is dictated in the manual of your boiler it is not necessarily the height in the water goes to when the boiler is running. What is the make and model of your boiler
Cost is what you spend , value is what you get.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
Jamie Hall Member Posts: 24,126
September 2017

A bit of a comment. The Hartford Loop is designed to be below the running water line, and thus always full of water. Full of water, no hammer. The Gifford Loop is designed to be above the water line, with just the condensate running in it. Nowhere near a full pipe, and very little velocity. No hammer. However, if the running water line is very near the top of the loop pipe, but slightly below (almost a full pipe), in principle you could get some hammer as the water line fluctuates in normal operation, pushing a nice slug of water into or out of the loop nipple. Does it happen? I'll take @Charlie from wmass 's word that it's pretty rare.
Both types must be vented to boiler pressure (not the atmosphere) to prevent siphoning. and to equalize pressures on the wet return.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
HVACNUT Member Posts: 6,053
September 2017

I'm not a steam installer, but is the Hartford loops reason for being to control hammer? I thought the close nip took care of that, but the Hartford loop itself was "invented" by someone, and required by the Hartford insurance company to prevent dry firing in the case of a broken return.
Is there a benefit of using a Gifford (Giffhart) loop over a Hartford loop, or does it depend on the job?
Danny Scully Member Posts: 1,434
September 2017

You're right @HVACNUT, the Hartford Loop was designed by the Hartford insurance company for the very reason you detailed. The Gifford loop, however, advertises a more stable waterline.
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Fred Member Posts: 8,542
September 2017

The Hartford loop was designed to keep the water level in the boiler up to where the loop connects into the equalizer, in the event a wet return, below that level were to spring a leak.
The Gifford loop, by design does a better job of maintaining a stable water level in the boiler.
Jamie Hall Member Posts: 24,126
September 2017

And no, neither of them will control water hammer, nor are they intended to -- indeed they can occasionally cause it. I wouldn't care to declare for sure, but the Gifford loop, being above the water line, probably does a better job of stabilizing the water line because it decouples the water in the wet returns from that in the boiler. With longer wet returns and a Hartford loop, there can be some "sloshing" back and forth. Shouldn't be a major problem.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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AMservices Member Posts: 610
September 2017

I was working with another heating tech installing a mega steam and we were talking about controlling the water level.
Before I could say "Giffordloop" he started telling me that he noticed when the return tied in above the water line, the water in the gauge glass would be much more stable. That's when I told him about Mr.Gifford and shared the attached article with him.
Then I told him how impressed I was that he was able to make that observation and not only that, keep piping your boilers that way, in spite of how it's been done for the last 120 years.
That was the first steam job i did after reading about the Gifford loop. Made so much sense to me I had to try it and haven't stopped.
Just because something works and people have been doing it that way forever, doesn't mean it's the only way it should be done or that it the best way to do it.
Off topic, look at how I've seen a false water line installed.
Haven't had to try that one, but I can say (on that job) it works.
HPACGiffordLoop.pdf 152.7K
ChrisJ Member Posts: 16,132
September 2017

Isn't the main reason for a Gifford loop to raise the water line, aka create a false water line?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
AMservices Member Posts: 610
September 2017

A false water line is designed to keep a wet return from going dry.
A Gifford Loop does a better job keeping the water in the boiler.
A Hartford Loop is connected 2 inches below the normal water line, so when the pressure inside the boiler is pushing down on the surface of water, the water can start backing out of the boiler. Water can't back out through the return if it's tied in above the normal water line.
ChrisJ Member Posts: 16,132
September 2017

AMservices said:
A false water line is designed to keep a wet return from going dry.
A Gifford Loop does a better job keeping the water in the boiler.
A Hartford Loop is connected 2 inches below the normal water line, so when the pressure inside the boiler is pushing down on the surface of water, the water can start backing out of the boiler. Water can't back out through the return if it's tied in above the normal water line.
Please explain how a Gifford loop would not raise the water level in a wet return.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
AMservices Member Posts: 610
September 2017

The pressure from the steam will be pushing back on the returning water, but not enough to overcome the weight of the water.
When it's pushing down across the surface of all the water in the boiler and there is an exit hole lower than the normal water line, that's when the waterline can start lowering.
ChrisJ Member Posts: 16,132
September 2017

Sigh.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
2
JUGHNE Member Posts: 11,204
September 2017

Chris, perhaps this is only for high dry returns that drop into a wet return at the boiler.
Charlie from wmass Member Posts: 4,357
September 2017

Gifford raises water level only amount equal to the height ut is above waterline. That said pressure is suppise to equalize through out the system. Steam pressure pushing at supply equals steam pressure at return. This of course only applies to systems that close all the steam vents during their cycle
Cost is what you spend , value is what you get.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
ChrisJ Member Posts: 16,132
September 2017 edited September 2017

Charlie from wmass said:
Gifford raises water level only amount equal to the height ut is above waterline. That said pressure is suppise to equalize through out the system. Steam pressure pushing at supply equals steam pressure at return. This of course only applies to systems that close all the steam vents during their cycle
A system that closes all the steam vents during a cycle?
What kind of evil sorcery is this which you speak of?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
1
unclejohn Member Posts: 1,833
September 2017

Small apartment buildings. Valves shut windows open.

for those experts of the Hartford loop (2025)

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