Gifford loop and slow returns

ubipa

Can slow returns cause pipe banging with a Gifford loop on a wet return? I have a one pipe steam system that has been running ok for the last 2 years and now is getting a little fussy. It's starts about 10min into the cycle with both mains closed and the pressure starts to fluctuate 1-2kpa with a slight fluctuation in the water line. Touching the leg of the return to the Gifford loop (8-10" below), I can feel it get real hot then cool. So I'm guess steam is getting past the loop and the water level is fluctuating there too.

I'm also noticing the B&J vent on one of the mains is burping a bit, which maybe part of the cause of the pressure fluctuation. Dang steam system... always needing so much attention. Any help would be greatly appreciated.

Jamie Hall

Is there an equalizer on the Gifford Loop? To the header?

ubipa

Yeah, an equalizer is there. I’m wondering if there is a blockage somewhere... causing Poor return flow or routing

ethicalpaul

I would be real shocked to have a blockage in such new looking pipes. My decades old return has some stalagmites and stalactites in it but still had plenty of passage available.

ubipa

The returns are original up to the copper and the mains are original up to the header. The system was a real train wreck until we bought the place. Steam is now going to places it hasn’t been for a long time I have also removed some lines/radiators after figuring out there was too much radiation. This was right before buying a new boiler (so the system is sized appropriately).

It’s in the back of my head that those rusty old rads that haven’t worked for awhile or something in the line I wrenched on broke some crud loose or something.

I just drained some water out after a cycle and there does seem to be quite a lot of precipitate. Maybe it’s just the dirty steam? I was really trying to limit draining the boiler to the beginning of the season.

ethicalpaul

What is dirty steam? What’s your definition of precipitate? I don’t know that term

ubipa

Rust particulate that is suspended/dissolved in the water to such a great concentration that it precipitates out. I believe it also carries the particulate through the state change and makes some dirty steam which isn’t very stable. This is all from my rudimentary understanding, so I could be wrong here Could the drop header be filtering a lot of this out and it’s flashing back in the equalizer?

Hap_Hazzard

A precipitate is a solid that forms in a solution. These solids can either stay suspended or settle to the bottom. This can happen in boilers when water is heated if certain dissolved minerals exist in concentrations greater than their solubility at higher temperatures, but it could also happen if a chemical is added that reacts with other chemicals already in the water.

Chris_L

@ubipa, are you sure the banging is in the Gifford loop? You should be able to tell by standing next to it while the banging occurs.

As for precipitates causing banging, I was recently getting banging inside one my boilers on startup (though more muted than water hammer in a pipe). I think it may have been caused by precipitates. In any case, some boiler cleaner seems to have fixed it.

The water in your sight glass doesn't look very clean from your photo (unless the discoloration is from some kind of boiler water treatment).

ubipa

I’m hearing flashing, but it occurs a little sporadically in single shots. I’ve heard it down by the Gifford loop/equalizer area, but sometimes louder instances coming from the header. Usually by the time I get close enough, the moment passes.

I do get a little boiling noise from stirring up the pot on startup.. the water is part SteamMaster pink (9-9.5ph) and half rusty orange. The condensate in the return is reasonably clear.

I decided to drain it, closed off the return and steamed off a good bit of the water. Now cooling with the air scrubber...

ethicalpaul

Thanks! OK so chunks of rust in the bottom of the boiler?

Could the drop header be filtering a lot of this out and it’s flashing back in the equalizer?

I don't think so. I mean if your steam is carrying over boiler water into the header then some chunks might be washed through there, but I don't see these tiny particles ganging up to make a blockage.

ubipa

I’m not too worried about the precipitate creating a blockage. Thinking more about the dirty steam not making it through the drop header and condensing into really hot water in the equalizer then flashing back. As the water boils down and if the return is slow.. the concentration of the particulate becomes high and there’s more dirty steam.

ethicalpaul

What's dirty steam again?

ubipa

Kinda like what happens after eating a bean burrito...

Fred

That's not a Gifford loop. It looks like a Hartford loop to me and if it is above the boiler water line, it can cause some hammer when steam hits the condensate. Have you dropped the water level in the boiler? As a test, fill the boiler to about 3/4 up the sight glass and see if the banging goes away. If it does, lower your Hartford loop to about 2 inches below the normal water line.
Nice boiler installation BTW!

ubipa

Thanks. I worked with a really good guy and it’s taken some tinkering. I think it’s the angle of the pic. The loop is above the waterline, basically at the top handle of the sight glass. It would be really hard to get it under the waterline without flooding the press gauge and vapor stat.

I ended up draining/flushing the boiler. It was pretty mucky.. Two cycles now and no banging. The cycle seemed to be a lot shorter with the clean water. Pretty crazy.. Seems to address the initial issue. The combination of whatever is mucking it up and the slow return feels like the real issue.

EBEBRATT-Ed

@ubipa
I agree with @Fred that is a Hartford loop and it sure looks too high to me. Measure from the bottom of the nipple coming out of that tee horizontally to the floor. The bottom of that nipple should be about 2" below the middle of the gage glass.

Check the install manual to see what they say. The piping looks good.

Maybe you need to skim the boiler

Fred

@ubipa said: "The combination of whatever is mucking it up and the slow return feels like the real issue. "
You may not have slow returns. With that Hartford loop up that high, that vertical pipe that creates the Hartford loop plus any other vertical drops you have on the returns is holding more water than they should before dumping it back into the boiler. The water in all of those verticals will find their own level, which, in your case is a few inches above the boiler water line. I guess I'm saying it is a "created" slow return.

acwagner

I understood the Gifford Loop to simply be a Hartford loop that is above the waterline. This article defines the elevation as at least 1/2" above the low water trigger point.

https://heatinghelp.com/assets/Uploads/HPACGiffordLoop.pdf

ubipa

Gifford vs Hartford, I thought the distinctive difference is that one is fully above the water line and the other fully below. Anything in between has a higher likelihood of creating noise. The loop on my system starts 3” above my water line (attached pics). Why are we saying it’s a Hartford?

The system went through the night without any noise. So looking back at the conditions when the noise was occurring.. the water was dirty, the boiler had pressure (1-2kpa), one of the main vents was burping, and the leg of the return loop was untouchable(possibly steam). Was the steam backing into the return, collapsing and causing pipe hammering?

acwagner

Any recent work to the system that would have introduced oil to it? Piping fixes, etc? It doesn't take much oil/debris in the boiler water to throw things out of wack.

If it worked fine for two years without problem I suspect the Gifford loop isn't the problem.

ChrisJ

Fred said:

That's not a Gifford loop. It looks like a Hartford loop to me and if it is above the boiler water line, it can cause some hammer when steam hits the condensate. Have you dropped the water level in the boiler? As a test, fill the boiler to about 3/4 up the sight glass and see if the banging goes away. If it does, lower your Hartford loop to about 2 inches below the normal water line.
Nice boiler installation BTW!

@ubipa and @acwagner are correct.

A Gifford loop literally is a Hartford loop above the waterline.
It should only cause hammering if it's partially above the water line.


Where is the actual hammering? Can you pinpoint it?
Does it seem like it's coming from the Gifford loop?


Can you give us a video of the water line? Is it really moving up and down a lot or just a normal amount?

ubipa

acwagner said:

Any recent work to the system that would have introduced oil to it? Piping fixes, etc? It doesn't take much oil/debris in the boiler water to throw things out of wack. If it worked fine for two years without problem I suspect the Gifford loop isn't the problem.

Nothing recent... unless it was building up. I was using the garage radiator over December, which is usually turned off. Maybe some additional rust from there. I don't think the Gifford loop is the problem, I'm more trying to understand it's behavior in the situation.

ChrisJ said:

Where is the actual hammering? Can you pinpoint it? Does it seem like it's coming from the Gifford loop? Can you give us a video of the water line? Is it really moving up and down a lot or just a normal amount?

The noise isn't like a few rounds on an impact hammer, just single shots ~10min into the cycle. I have heard it down by the loop and equalizer, with louder shots emanating throughout the header. Right now, the kettle is clean so the water line is rock solid. When the noise was occurring, the boiler water line was dropped by 1-2" and there was probably about 1" of movement. So it wasn't close to the loop.

Seems like the Gifford loop, being above the water line, would be sensitive to the volume and pressure equalization of the wet return. Low volume, slight negative press and steam backs up into the return? Is this just part of the character of this setup? Maybe my returns are getting anemic

Fred

@ChrisJ and @ubipa A Gifford loop uses a Wye fitting, not an elbow. I'm sure if the inventor could have gotten by using an elbow with consistent results, he would have. Show me, in the Inventor's documentation where he says a Wye and an elbow are both viable options and show me where any boiler manual says to install a Hartford loop above the water line. Some manuals do recommend a Gifford loop and they all require a Wye.

ubipa

Looking at the patent filing, it doesn’t state the connection type. The image in the patent looks like a close nipple though. Where is this wye requirement documented?

ChrisJ

Fred said:

@ChrisJ and @ubipa A Gifford loop uses a Wye fitting, not an elbow. I'm sure if the inventor could have gotten by using an elbow with consistent results, he would have. Show me, in the Inventor's documentation where he says a Wye and an elbow are both viable options and show me where any boiler manual says to install a Hartford loop above the water line. Some manuals do recommend a Gifford loop and they all require a Wye.

I'll do better than that my friend.

@HGifford Mr Gifford, I'm sorry to bother you, but can an elbow and a tee be used with a Gifford loop, or must it be a wye?

Do you see any problems with the way your loop is used in the pictures posted by @ubipa ?

Fred

Thanks @ChrisJ , anxious to hear his response. @ubipa The Wye replaces the elbow or, in most cases the close nipple that goes into the equalizer.

ubipa

Haha.. is there really an account on here, just for that?!

I can see how a wye would be better. Not sure I’m going to change it though..

KC_Jones

ubipa said:

Haha.. is there really an account on here, just for that?!

As far as I know it's the account of the inventor.

Hap_Hazzard

It's my understanding that a wye can be used in either Hartford or Gifford loops. The reason for using a wye is, as I understand it, that it reduces the likelihood of water hammer, just as a close nipple is preferable to a 1" nipple. In the article @acwagner references above, Mr. Gifford seems confident that Gifford loops never hammer anyway, so the argument for using a wye in a Gifford loop appears weaker than in a Hartford loop.

Hap_Hazzard

KC_Jones said:

ubipa said:

Haha.. is there really an account on here, just for that?!

As far as I know it's the account of the inventor.

Yes, it is. He's posted twice. Didn't mention a wye in either one. Or in the patent. Or in the article. I kinda think it's down to personal preference, just like it is in a Hartford loop.

Chris_L

I think a lot of the confusion here relates to the way the Gifford paper defines the water line. It is not the normal water line (NWL) as we know it. It is the lowest water level before which the automatic feeder is trigger--if you have one.

The installation manual for my boiler has the NWL at 26". It recommends the Hartford Loop at 24". But the lowest permissible water level--based on the mark on the MM67 low water cutout--is at 20.5". (No autofeeder for me.)

So according to Mr. Gifford, I have a Gifford Loop, and according to Burnham, I have a Hartford Loop. And I really don't care what you call it, because I don't get any hammer in it at any water level seen in the sight glass.

What I would like to know, @HGifford, is how did you get a patent for something in 2002 that Burnham was recommending in the 1980s?

ChrisJ

Chris_L said:

I think a lot of the confusion here relates to the way the Gifford paper defines the water line. It is not the normal water line (NWL) as we know it. It is the lowest water level before which the automatic feeder is trigger--if you have one.

The installation manual for my boiler has the NWL at 26". It recommends the Hartford Loop at 24". But the lowest permissible water level--based on the mark on the MM67 low water cutout--is at 20.5". (No autofeeder for me.)

So according to Mr. Gifford, I have a Gifford Loop, and according to Burnham, I have a Hartford Loop. And I really don't care what you call it, because I don't get any hammer in it at any water level seen in the sight glass.

What I would like to know, @HGifford, is how did you get a patent for something in 2002 that Burnham was recommending in the 1980s?

I'm not an expert on it, but if my understanding is correct what you suggested could hammer sometimes.

The connection must either always be completely full of water, or completely empty. Never partial.

So a Gifford loop would need to be completely above the highest water level possible in the equalizer.

Hap_Hazzard

A Gifford loop is partially full when the boiler is running and the condensate is returning.

ChrisJ

Hap_Hazzard said:

A Gifford loop is partially full when the boiler is running and the condensate is returning.

This is true.
But very little, no?

I picture it being like a steam main or radiator run out. Very little pouring over into the boiler side.

Chris_L

ChrisJ said:

Chris_L said:

I think a lot of the confusion here relates to the way the Gifford paper defines the water line. It is not the normal water line (NWL) as we know it. It is the lowest water level before which the automatic feeder is trigger--if you have one.

The installation manual for my boiler has the NWL at 26". It recommends the Hartford Loop at 24". But the lowest permissible water level--based on the mark on the MM67 low water cutout--is at 20.5". (No autofeeder for me.)

So according to Mr. Gifford, I have a Gifford Loop, and according to Burnham, I have a Hartford Loop. And I really don't care what you call it, because I don't get any hammer in it at any water level seen in the sight glass.

What I would like to know, @HGifford, is how did you get a patent for something in 2002 that Burnham was recommending in the 1980s?

I'm not an expert on it, but if my understanding is correct what you suggested could hammer sometimes.

The connection must either always be completely full of water, or completely empty. Never partial.

So a Gifford loop would need to be completely above the highest water level possible in the equalizer.

Perhaps it could hammer--in theory. But I have lived in a house with 2 boilers piped this way for 26+ years, and they have never hammered--whether the nipple was full or empty or somewhere in between.

And that is what Mr. Gifford says in his paper. His loop doesn't cause hammering.

But maybe it has something to with the unique way my loops were piped . For example:

EBEBRATT-Ed

@ubipa

Call it a hartford, call it a gifford it dosen't mater. The only difference between the two is the height of the tee.

Dosen't anyone see the problem here...look at the pictures, it's right there.

The bottom of the Gifford/Hartford is 32". The top of the sight glass is 31"

And close nipple ,street elbow or Y fitting is not a big deal. Any of those 3 will work.

The difference is which fitting presents the least amount of water surface exposed to the steam in the equalizer.

You can't run a boiler with the top of the sight glass is 31" with a return connected at 32", its just common sense loop or no loop

ubipa

> You can't run a boiler with the top of the sight glass is 31" with a return connected at 32", its just common sense loop or no loop

That was a true Jerry McGuire moment until the end, then I started thinking about the stock options I’d loose what do you mean you can’t run a return higher than the top of the sight glass?

Hap_Hazzard

ChrisJ said:

I picture it being like a steam main or radiator run out. Very little pouring over into the boiler side.

It's the total output from all your radiators and piping, so it could be a lot, but I'm not really sure what it looks like. Dang pipes—can't see through 'em. Hey, @ethicalpaul, how 'bout putting a glass Gifford on that new boiler?

ChrisJ

Hap_Hazzard said:

ChrisJ said:

I picture it being like a steam main or radiator run out. Very little pouring over into the boiler side.

It's the total output from all your radiators and piping, so it could be a lot, but I'm not really sure what it looks like. Dang pipes—can't see through 'em. Hey, @ethicalpaul, how 'bout putting a glass Gifford on that new boiler?

I had looked into doing pyrex piping when I installed my boiler.

It was a little too expensive, even for how much I'd like it.

ethicalpaul

Well I have a sight glass on my return so I know how much water is returning. The boiler manufacturers usually tell how many gallons per minute.

It’s more than very little!