groaning copper tube boiler

Dave_61

I have a Lochinvar boiler with Ergomax tank which acts as a buffer. It has been practically silent until tonight. I heard this kind of groaning as the boiler was trying to heat DHW. I went downstairs and boiler was definitely making the sound, and I could feel vibration in copper pipes to Ergomax tank.
The only thing I noticed that was weird was that our system pressure was lower than normal (about 12-15) even though the water was at temp. It normally is about 22. Also, the specs for the boiler say that the pressure must not get below 12 psi.
Could the low pressure cause the vibration we were hearing? What would cause the pressure to be low like that besides a leak? We have 50:50 water and glycol and have no leaks anywhere. Thanks.
Dave

kevin coppinger_4

sounds like...

there is a flow issue...is the circ on its way out? kpc

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Unknown

boiling water

Shut her down before someone gets hurt.

Got flow? Need more info.That slimy glycol could have went after the gauge and you have no pressure. No PSI,,, no pressure differential,,, boiling water and GROANING.

Glycol needed?

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Dave_61

there are

3 gauges....One on the Ergomax and a gauge on the inlet and on the outlet of the boiler. All were reading low pressure. The pump is only about 3 months old. The temp differential between the inlet and outlet of the boiler was about 10 degrees and the water temp at that point was about 160 coming out of the boiler, so I would think we had adequate flow.
Could the low pressure cause the groaning?
And what would cause the pressure to be low besides a leak?
Once or twice in the past few months, I had noticed the pressure to be on the low side, but then it would increase on its own. (Our water supply valve is always off as we have glycol in the system). So this is the first time I have added water in about 4 months.

steve gates

How old is the glycol? Going bad, causing foaming.

Dave_61

groaning copper tube boiler

Glycol is only about 4 months old. We had added the Ergomax to our copper tube boiler about 4 months ago because of the racket it was making as well as the short cycling. Since then it has been very quiet. It was noisy again today. I went downstairs and water temp was about 170...delta t between inlet and outlet was about 10 (so good flow) and system pressure was about 20. I pulled the PRV on the Ergomax and hot foamy water sot out, but that could just be because it was under pressure as it came out of the PRV that it was foamy.

Tony_23

Low pressure

Check your exp tank. You can lose air from that and not know it, lowering your system psi. Try filling to 20# and see if it goes away.

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hr

Was the pump sized to the 50% glycol?

could be the circ is undersized?
What is the static pressure without the pump running? Is the pump on the return (pumping into)to the boiler, as it should be?

Was the system cleaned and flushed before the glycol was added? Was the glycol blended with DI or DM water?

If it has started over a period of time I would suspect hardness in the fill water is putting a thin coating on the HX tubes. If the circs are sized and installed properly I'd check water quality.

Chemical Specialities in Denver has a product to help quiet boilers with hardness build up. Works very well on glycolled copper tube boilers. It loosens the deposits and keeps them in suspension. CST-50 (closed system treatment) 24 ounce bottle will handle 10 gallons of glycoled system capacity and lock up up to 1000 grains of hardness.
An alkline chelate product, basically.

I'd still prefer the system be cleaned and the hardness kept out of the system however. Instead of treating it once it's in there

It could just need a pressure boost if the fluids are clean and ph is good. Certainly the easiest thing to try first Good idea to keep a glycol fill system in place for at least a few months to replace any air that may burp out. Or look for a leak if the pressure continues to drop on a regular basis.

Also check with Lochinvar, some of the copper tube boilers only allow glycol to a 35% mixture. same with mod con boilers.

hot rod

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Dave_61

The pump is

a Taco 0010. It was definitely sized for the current situation with the glycol.
Its job is to pump from the Ergomax to the boiler (it is on the return to the boiler).
The static pressure (I assume you mean with everything off) is between 5 and 10 psi depending on whether i am reading the boiler gauges (10 psi) or Ergomax gauge (5 psi).
I isolated the expansion tank from the system, and its pressure is reading 20 psi.
I will have to send a sample of the water/glycol to Noble co (NoBurst manufacturer). Yesterday is the first time I have heard this, and system was repiped and filled 1/06.
The sound is definitely coming from the boiler heat exchanger.
We did not clean the system before refilling it, but at the time it was only 5 years old. Probably should have done that, but now we have $400-500 worth of glycol in it.
Do you think it sounds more like mineral buildup?

hr

sort out your gauge snafu

first. If the tank is located next to the boiler you should not have that much of a pressure difference. one, or both, gauges are fibbing

Lochinvar wants a minimun 12psi fill pressure. The expansion tank should be set to the fill pressure before it is installed. 12 psi fill= 12 psi fill pressure at the tank schrader valve.

Did you recently check the fluid %? Do you know you have a 50% mix for sure? 50% is max for the MiniFin, but check with Lochinvar on your exact model if the manual does not tell you.

Again hardness and TDS is a number you need to know for your fill water. The manual gives you the acceptable spec.

No reason the fluid could not be purged and saved while the system is cleaned out properly.

Good idea to send a fluid sample for a check to Nobel.

There comes a time where the cost of inhibitor boost chemicals out weighs the cost of starting with new fluid, if it is compromised. The product I mentioned above is a boost and cheleate. Best check with Nobel before you start blending their product with "fixes"

Get some new gauges, adjust the expansion and fill pressure and see what happens.

Keep in mind if the HX is coating with deposits, in addition to noise issues you are dropping efficiency. Possibly considerably. Even a couple of thousands of build up starts to hammer the HX efficiency.

If the deposits get bad enough you will ruin that HX as it cannot do it's job properly with a film build up.

The factory will know that if, or when, it is sent in for warranty claim

hot rod

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Jerry_15

All good advice, but make your life a little easier and make up a test gauge that you can simply screw on to the any boiler drain/hose bibb to get an instant cross-check. You can check your gauges, system pressure, jack it to 15 and see if that solves the problem, without getting out the wrenches. I keep several with different pressure scales and use them constantly. What a time saver. Good luck.

Dave_61

The pressure this morning

was about 25 psi, where it normally is with the boiler hot. (our highest air vent is about 35 feet above the boiler). Instead of groaning, it actually sounds more like a semi-truck is idling in the basement. This is noticeable most in the living area (not so audible in basement). I also noticed that the needle on the pressure gauge on the inlet of the boiler is vibrating (like a seismograph). Maybe a bad gauge? But the sound I thought was a groaning is more like a vibration.
When I opened the bypass at the Ergomax tank, which is normally closed, the sound became much more high pitched and audible in the basement (more like a groan).

Unknown

good luck

Good luck finding a exorcist today, they are usually off on mondays after busy weekends...

Drew_2

Additive

Watch out for what you add to system that is heating DHW. The toxicity of some of these are very high.If you have a failure, you'll be drinking this fluid.

Ike Gatlin

help

Dave,
I assume you are still having this problem.
All the suggestions posted here are viable. It my do good to get a service guy out there that has a clue or two.

From what I have read, flow seems to be the issue here. The air from the ergomax is also a good indicator that you are boiling the water on the tubes of the boiler. You also mentioned that you had 50/50 glycol... how do you know that? Are you sure it isn’t actually higher? More glycol than water?

Shoot me an email at igatlin@lochinvar.com I can help you find a good heating contractor locally.

Ike Gatlin

Jerry_15

Oh oh - pressure higher when it's hot? Almost surely ex tank trouble. I spend a little more and get a potable water type when there's chemicals involved. Cop tube jobs have a nasty habit of developing a film in the tube that causes this kind of problem. Teledyne sells a rotary wire brush to "cure" it, RPITA. The manufacturers always have a tech support line, and while it may not have the same ambience as the Wall, they are pretty knowledgable about their own product line, especially in regards to recurring problems (although it is NEVER a defect, or poor design). Local reps are occasionally very knowledgable, and may be able to steer you to a clever local techy, which is really what you need. Letting it continue is stressing the boiler, and cop tube boilers don't like stress. Good luck. PS 10 deg delta is really sailing, but usually ok. Try restricting flow to 20 if you have a valve on the DISCHARGE SIDE of the pump, also over-firing will definately cause this problem on cop tubes.