problem solved...was groaning copper tube boiler

Dave_61

I was the guy who posted that my copper tube gas-fired boiler was groaning 4 months after a repiping job. We have a 50:50 glycol mix, and I sent a sample to Noble Company to have it tested. Some of you had said that it was a flow issue, but the delta t between the inlet and outlet on the boiler was 10-15 degrees.

Well, my neighbor the plumber stopped by tonight and ran some water through the boiler and out the boiler drain because he thought there might be some air that had been trapped in the heat exchanger when the pressure was low.

The noise stopped immediately. I don't understand how air could possibly get in the heat exchanger 4 months after the repiping. He also recommended leaving the autofill valve open so if the pressure transiently drops, it would replenish the water. He says that we would notice any type of leak that would be substantial enough to dilute our 40 or so gallons of antifreeze.

I just don't understand how air could possibly get in the heat exchanger 4 months after the repiping.

Jeff Elston

Think like Air

> I was the guy who posted that my copper tube

> gas-fired boiler was groaning 4 months after a

> repiping job. We have a 50:50 glycol mix, and I

> sent a sample to Noble Company to have it tested.

> Some of you had said that it was a flow issue,

> but the delta t between the inlet and outlet on

> the boiler was 10-15 degrees.

>

> Well, my

> neighbor the plumber stopped by tonight and ran

> some water through the boiler and out the boiler

> drain because he thought there might be some air

> that had been trapped in the heat exchanger when

> the pressure was low.

>

> The noise stopped

> immediately. I don't understand how air could

> possibly get in the heat exchanger 4 months after

> the repiping. He also recommended leaving the

> autofill valve open so if the pressure

> transiently drops, it would replenish the water.

> He says that we would notice any type of leak

> that would be substantial enough to dilute our 40

> or so gallons of antifreeze.

>

> I just don't

> understand how air could possibly get in the heat

> exchanger 4 months after the repiping.

Jeff Elston

Think like Air

Thanks for the line Dan!

Dave_61

Could anyone tell me the best way to flush air through the boiler hx in case this recurrs? We have a draincock on the otlet pipe.

Brad White_74

Spirovent

or one like it. Is the boiler piped P/S? IOW will there be constant flow through it -as well it should be- to keep "polishing" any developed air out of it.

Dave_61

The noise seems to be starting again...definitely quieter, but it seems to be recurring.
What is the best way to purge air from hx? We have a draincock on the outlet pipe and one at the base of the Ergomax. We do have a Spriovent, but the air seems to be trapped in the heat exchanger.
How do we then stop the antifreeze from foaming and the problem from recurring?

marc

copper fin tubed boilers

we use Lochinvar for snowmelting systems, the groaning can be attributed to the following:

1- low system pressure
2- low flow
3- high glycol mixture

try to elevate the system pressure to above 50 psi or thin down the glycol mix, 50% seems high.


marc

Dave_61

The sound this morning is quieter than it was but still present.
We have no evidence of a leak at all. The only thing I can think of is the following....
All winter, the system worked well with no noise.We have 3 air handlers as well as DHW and radiant floor in master bath. As the warmer weather started and the heating zones stopped running, the system pressure dropped and air entered through one of the air vents in the attic (The highest vent is about 35 feet above the boiler though that one was shut off, but there was another about 22 feet above boiler).
Now we seem to have a foaming problem in boiler. Not sure why it hasn't worked itself out of hx and through Spirovent, but it is still rumbling, just not as much.
Does the above scenario seem plausible?
What is the best way to get the foam out of HX and prevent ir from recurring?
Dave

Brad White_9

Of course you are pumping away, right?

Air entering through high point air vents leads me to believe that you are pumping toward your expansion tank. Have to ask.

hr

Have you checked the glycol% yet

I still feel this could be the root of you problems. Since you are asking... if it were me I would drain the whole system, run a cleaner for a few days, get the glycol test results, and start fresh from square one.

You have too many unknown variables right now. It really should be cleaned and started correctly to protect your investment and provide years of trouble, and noise free, operation.

Until you have some solid data all we can do is throw guesses out to you, based on past experiences. You could spend time and money walking the wrong path.

Sounds like Lochinvar wants to get involved. Take Ike up on his offer. He wants it fixed as much as you do

hot rod

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George_10

If you decide to clean the system

you could use our hydro-solv 9100. We have had great success using it in similar situations. As Hot Rod said, you could drain the system, save the fluid and reuse it when you have the cleaning done.

Also check the glycol percentage. Drew should be able to give you that answer from the sample you sent him.

If we can be of further help, call Rhomar at 800-543-5975.

George

Dave_61

Hot Rod,

If we drained and cleaned the system, would I save the glycol and reuse it after cleaning?

Duncan_2

Glycol and low mass copper

Dave, it's hard to answer your purging questions without knowing the system configuration. But marc sums it all up nicely.


I start with the least intrusive way by raising the system pressure and lowering the boiler temperature if that's OK with your heat emitters - maybe not with hydro air. Gotta be OK with your boiler relief valve, too. Also look for ways to increase flow.


Speaking in generalities, if I have the opportunity to re-pipe, I try to increase flow through the boiler by using a bypass or a larger circ (within reason).


Also, I pump INTO the boiler, but away from the expansion tank. Lots of copper fin tube manufacturers recommend this arrangement, and from experience I can say it avoids problems, assuming your pressure relief valve is sized appropriately.


If you have snowmelt and it's not isolated with a heat exchanger, the auto fill is a no-no. I've seen systems freeze from makeup water replacing glycol and raising the freeze point if the system leaks.


If it were me, I'd save the glycol and test it to see if it can be re-used.

Kevin Koenig_4

Harmonic Resonance.

This is no mistery. I have seen this many times in copper fin tube boilers. All systems are different. In some systems a thin film or scale layer can forme on the inside of the tube wall, usually on the end of the second pass where the water temperature is high. Water trapped between the layer and the tube wall will flash to steam at a particular frequency under certain conditions. Spacific frequencies will set up harmonic resonance on the many fins protruding fron the pipe wall. This causes the groaning sound you are hearing. The only perminant fix is to rod out the tubes and eliminate the layer of material that isolates the water traped under it from the main water flow in the tube . Monkeying around with pressure will have some affect on the problem but usually will never fix it completely. K.K.

Dave_61

This is from Drew Longnecker at Noble Co, maker of NoBurst:

The freeze protection of the fluid is +14 degrees F. The pH was 9.2 .
This seems to be a combination of antifreezes. We do not do water
hardness testing. If done,this test would have to be done on the water
alone.

hr

The ph looks ok

but a + 14 doesn't equate to a 50% mix. I don't think anyways without having the Nobel product lit in front of me. So probably not a rich glycol solution problem.

I'm not sure I would break down the boiler to rod it out just yet. That product from Denver has worked for me and many others to handle small build up. It would not require a drain down.

I don't think the HX can take 50 psi. I doubt the relief valve is more than 30 psi. And 45 psi may be the max the manufacture allows.

Cleaner from Chemical Specality and a slight pressure increase would be my next steps.

If it does need to be taken apart to rod out, consider a new HX if the thing is 10 years old or more.

Or better yet replace the whole thing with a Lochinvar Knight mod con and save 30% in fuel costs

hot rod

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Dave_61

Hot Rod,

I spoke with Drew, and he said that +14 deg = about 30% mixture.
The prv on the boiler is 30 psi...currently, it is running at about 25 psi.
Do you know of the chelating agent that they used in Denver?
Would it possibly be scale if all the plumber did yesterday was run some water through HX and the noise is 50% better?
It is definitely a harmonic type noise that starts within 10 seconds of burner firing and stops as soon as burner shuts off. I actually have only 1 burner running (140K btu vs 300K btu), and it made no effect on decreasing noise.

hr

I wouldn't rasise the pressure anymore

Those boilers can, and do run just fine at 12 psi with glycol. Hundreds of them scattered across the Intermountain west. All brands all sizes.

And you should not have to lower the temperature to mask a problem. That boiler should be able to run glycol at 180 or so without a problemn. If your system needs 180 that you should get 180. The Ergomax reallys needs that temperature to perform to spec, at least for the DHW production.

You need to go back to when the noise started. Sounds like the addition of the glycol. How old is the boiler? Comes a time when they wear out

It could have been partially scaled and the glycol was just enough to put it into a moan.

The CST 50 treatment I have used is probably the same stuff Eatherton uses. Seeing as it comes out of Denver. Contact the fellow Mark mentioned dennisbellanti@ferguson.com to purchase some.

I'm curious how you got from a 50% down to 30%. Has additional water been added. You are positive there is no leak in the system? Every time additional water is added, so is the hardness that adds to the problem.

hot rod

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Steve M_2

Why the Glycol?

Hey Dave,

I don't believe I read why you even have glycol in the system to begin with? I think Kevin is right especially if the glycol was funky before you did the re-piping. I'd get rid of the glycol if you don't have any exposed pipe or anything. You can try cleaning the innerds of the heat exchanger but it doesn't always work. It's a fairly easy job to replace the heat exchanger and I think they're still available.

Steve

Dave_61

The system was repiped and

glycol added the last week of January (about 4 months ago). I heard no noise from it until this past Saturday. It struck me today that it sounds like an oil burner (although it is natural gas).
When it was overheating (before the buffer tank was added), it sounded like a howl.
The boiler itself is about 5 years old.
I also notice that the needle on the pressure gauge on the inlet to the boiler is steady at 25 psi when the pump is running, but as soon as the burner comes on, the needle starts vibrating. The needle on the boiler outlet pressure gauge never vibrates.
As far as the % glycol, we just guestimated how much to add when we filled the system. I then shut the water fill off manually, so I can't imagine that it would have run for 4 months without us noticing if there were a leak.
I'm just at a total loss with this thing.
Instead of emptying the heating zones that go to the 3 air handlers (a total of about 15 gallons), what would you think about my dumping the glycol water mix from the boiler and Ergomax (maybe 80 gallons), and treating that loop with TSP and refilling with glycol. Would that work OK?

Dave_61

We have 2 air handlers in attic spaces as well as

some radiant tubing under a cantilever that is exposed to cold temps in winter. We live in Northern CT so it gets down below 0 in dead of winter. I would love to get rid of the glycol if possible.

hr

Tough call on the glycol need

If the pipes are onn the top side of the insulation in the overhangs, I'd not worry too much.

They do make freeze stats for attic mounted air handlers. Dan Foley turned me onnto those a few years back in Memphis

In your case glycol is not mandatory, as it would be in a snow melt or possibly a garage.

It's insurance! YOU need to decide if it is worth the cost IE the problems you are encountering. Typically on a zero day your system would run darn near non stop so a freeze up should not occur. Plenty of systems in cold climates without glycol.Many BB systems have pipes in the outside walls.

Extended power outages could be an issue, but then again your water lines do not have glycol in them.

An argument for glycol could be made in either direction in your case. Looks like you are getting first hand experience with the pros and cons

hot rod

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[Deleted User]

What your neighbor did...

was wash off a little of the scum that affects the fluid to copper interface. The noise WILL be back, I guarantee it. Air does not cause a moaning sound. It causes a distinct gurgling sound. Sounds like marbles rolling through the pipes.

As for inadvertent dillution of your glycol, it's your system. Freeze it the way you (or your neighbor the plumber) wants it to freeze.

For me and my money, we install low pressure cut off backed up with a low water cut off and DO NOT MAKE ANY WATER MAKEUP CONNECTIONS to the system. But, we like doing it right the first time... Especially when dealing twith the ick of glycol.

The only time a relief valve leaks anc causes inadvertent dillution is whe no one is watching....

Make sure you drop a buck or two off at the Wall. Purchase some bricks or books to help keep the Wall strong.

ME

Drew_2

Cleaners/Chelates

Most Chelates use EDTA as the chelating agent. This works very well in steam boilers that are flushed after their use.But you should watch where you use them in hydronic systems because of the multi-metals that are used in these systems. Ask the manufacturer of the Cleaner/Chelate if the product contains EDTA.
I've attached a document from DOW Chemical on the metals that it should not be used with.

Kevin Koenig_3

Easy to rod.

The Mini-fin is easy to rod /brush out if the rear of the HX is exposed and accesable.. Remove the 3/4" plugs that are screwed into the HX. (this is the hardest part)This gives you a clear shot down each of the eight tubes. K.

Dave_61

This sound is different from

the howling that the boiler made in a low flow situation. It is more like a rumbling sound. I spoke with a Lochinvar rep who thought it might be a combustion problem (either a high gas pressure or a low draft or a cracked burner).
Does this sound plausible?
Dave

Steve M_2

funny sound follow up

Checking the manifold gas pressure would have been one of the things a real service person would have done. Regulators do go bad and it could be over fired. Also I would have pulled the burners to clean and examine and to also get a look the the exterior of the heat exchanger. If the flue gases where condensating before the repipe job, it could have dripped onto the burners causing damage such as splitting. I've also seen burners split if the exterior of the exchanger is clogged causing them to overheat but usually a rollout switch would have opened before that would happen. As far as the interior or the heat exchanger tubes, I've tried removing the plugs to clean the tubes without alot of success. I think if you removed the plugs when the boiler is new and before it's fired and tefloned taped and doped the plugs, the plugs might come out easier down the road. Chemical cleaning is iffy too.

I haven't read all of the posts on this but you need to get an experienced boiler man to look at this. Ask the Lochinvar rep to refer someone.

Steve

Steve M_2

funny sound follow up

Checking the manifold gas pressure would have been one of the things a real service person would have done. Regulators do go bad and it could be over fired. Also I would have pulled the burners to clean and examine and to also get a look the the exterior of the heat exchanger. If the flue gases where condensating before the repipe job, it could have dripped onto the burners causing damage such as splitting. I've also seen burners split if the exterior of the exchanger is clogged causing them to overheat but usually a rollout switch would have opened before that would happen. As far as the interior or the heat exchanger tubes, I've tried removing the plugs to clean the tubes without alot of success. I think if you removed the plugs when the boiler is new and before it's fired and tefloned taped and doped the plugs, the plugs might come out easier down the road. Chemical cleaning is iffy too.

I haven't read all of the posts on this but you need to get an experienced boiler man to look at this. Ask the Lochinvar rep to refer someone.

Steve

Dave_61

Steve,

I'm having someone come next week. I cranked down the gas flow incrementally until the boiler was struggling, and the noise continued. So, I'm totally at a loss.

Duncan_2

Cleaning HX tubes

Kevin, what kind of cleaning tools do you use to rod out Minifin boilers? I've got a few out there that could probably use it at this point. Thanks.

Duncan

Dave_61

Guys,
I have no clue.....Here's what i did.
I closed the valves to isolate the boiler and relieved the pressure. I replaced the bad T&P gauge and then let some more water run through the boiler before recharging the system and restarting it.
It is completely silent again.
And I closed the boiler outflow valve about 10%. The DDT reads between 20-25. It seems like the DDT decreases on its own from 25 to 20 as the boiler nears operating temp.
Any ideas why the sound would have gone away?
Only time will tell whether it comes back.
The pressure needle on the new inlet gauge does move back and forth a little but not vibrating like the old one did. Is that normal to see a few psi of movement?
Thanks again. I will be making a donation to The Wall for all your help.
Dave