Boiler Failure After Two Years

HeatingHelp · December 2018

Boiler Failure After Two Years

The boilers (and there were 20 of them) were laying out there in the parking lot, not far from the boiler room door. I could see them as Joe and I drove up. “Nobody knows what happened,” he said. “All twenty of them cracked, and they’re only two years old.”

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liveto99 · December 2018

That did not cause them to all fail the same day. In the spring they shut down and the relief valves got sealed with the lime. It may have happened to one at a time but the last one sealed shut as the boilers sat idle. When they started up The pressure tanks probably had failed by this point due to the build up of lime cracking the diaphrag, because of the pump issue causing fresh water intrusion. As the boilers heated up all of the water in the building there was a large expansion due to the temperature rise and the pressure probably shut up past 200 psi or so causing a massive failure of all the boilers at once. I have seen this in a house with cast-iron baseboard and it blew out about eight sections at once. I don’t know why all the cast-iron sections break at once I assume there may be some flex when the pressure is completely relieved and it causes a cracking and failure throughout the system, on similar cast iron pieces.
A little water treatment would also be a recommendation.

BobC · December 2018

There is always a reason - you just have to figure it out.

Decades ago I was working on a new power supply design for the navy. This supply provided high voltage for a crt display and had crazy tight specs - 10 volts variance on a 10,000 volt output. I finally got the supply comfortably withing spec so we started to run temperature tsts to see how the supply worked across the full temperature range. To do this you write a data sheet at room (25C), cold (-55C), hot (+65C), and again at room temp. The two room temp runs were different and that put us out of spec.

I started measuring everything to see what was going on and it didn't make sense, sometimes everything worked and sometimes it didn't and I could not find out why.

My lab space was in a separate area and the bench was a little dim so I had a swing arm magnifying glass lamp that i used to put a little light on the subject. Also because I got some sun in through the east facing window; I needed the extra light mostly after lunch. After a couple of days of poking around I noticed something odd, the output voltage was different in the morning than it was in the afternoon.

I then discovered I could cause a voltage drop just my shading the supply from light, in a short time I located the area that was causing the problem. There was a small diode at the input of the error amp and it was light sensitive (clear glass over the diode junction) , it conducted more in bright light then it did when lighting was dim and this caused the output to shift.

The cure was dirt cheap, one drop of black epoxy was used to cover that little 1N4150 diode so light could not reach the diode junction. I talked to the manufacturer and the started shipping the diodes with a shielded junction.

Bob

ADEY_NorthAmerica · December 2018

Did anybody test the water quality of the system? The holes you’re talking about could be pitting corrosion. Pitting corrosion is usually found on aluminum or stainless steels metals and as a result, can cause various sized holes and can even pierce pipework. As ‘liveto99’ mentioned, water treatment chemicals are certainly a must for this system – cleaner and protector should do the job, but you also need to ensure that the water is flushed.
Another cause of boiler breakdowns or blow-outs is black iron oxide. As air gets into the system, it oxidizes to form black iron oxide sludge. This sludge, or magnetite as it can also be referred to, forms on black iron pipework and any cast-iron sections that are part of the whole system. It can block waterways, foul pumps, and even block heat exchangers, causing them to crack and as a result, the boiler blows. Not only do water treatment chemicals need to be used for a system like this, but also a magnetic dirt filter!
We’re seeing instances lately of sludge harming many systems, especially as new high-efficiency boilers and ECM pumps are being installed.
Even on new systems, black iron oxide is still present. We recently had a case where a filter was installed in a new home and even just within 3 months, that filter had a layer of sludge captured. Imagine what it would be like after 2 years!
It might not be the issue in this case, but it’s always worth checking and ensuring the system is completely protected.

NY_Rob · December 2018

ADEY_NorthAmerica said:
We recently had a case where a filter was installed in a new home and even just within 3 months, that filter had a layer of sludge captured. Imagine what it would be like after 2 years!

Would you mind providing a link to such a filter?
I do have a dirtmag on my system but am interested the the filter idea too.

Jackmartin · December 2018

That is like this system I repaired for a lady two weeks ago. I was doubting my sanity for awhile I would set the fill at 12 psig a
and within 15 minutes the pressure shot up.to over 32psig. It never did it before because the brains servicing the system never looked to see if it had a pressure relief so who cared how high the pressure went. It is a Crane Viking coal fired conversion with the high limit jumped out. I finally had to watch this thing for 6 hours and the magical fill pressure was 9.5 psig cold. Heating to 180 the pressure went to 15 psig. I have never had that happen before and yes the expansion tank was drained and connected to the system. Anyone have any thoughts? Wierd! All the best and Happy Holidays Jack

DanInNaperville · January 2020

NY_Rob said:

ADEY_NorthAmerica said:
We recently had a case where a filter was installed in a new home and even just within 3 months, that filter had a layer of sludge captured. Imagine what it would be like after 2 years!
Would you mind providing a link to such a filter?
I do have a dirtmag on my system but am interested the the filter idea too.

Might have been something like this: https://www.supplyhouse.com/Caleffi-120161A-000-1-NPT-FlowCal-Y-Strainer-w-Integral-Ball-Valve
I've been looking at adding one to my system.

Henry · January 2020

NY_Rob use the Caleffi Dirtmag. It removes all magnetite and acts as a strainer for larger particles.

hot_rod · January 2020

A mag sep is you best removal device for magnetite, any type of filter or membrane would plug quickly. You would be flushing and servicing a filter weekly

The magnetite particles can be tiny, .05 micron. The oxide needs to be attracted to a magnet out of the flow. You would need a microscope to see the fine particle size of magnet, it can look like ink, we refer to it as boiler ink.

Not air so much as O2 that causes ferrous metals to break down. The system can be 100%, air and fluid tight, hold a 100lbs air or water test and O2 can still get in. Heating water drives the O2 out, you have "dead" water in a boiler after some run time.

However O2, at the molecular level can still enter an air tight, dead water system. Even even barrier pex allows SOME O2 in as do seals, packings, etc.

retiredguy · February 2020

Many years ago I was starting 2 Bryan Flex Tube boilers in a nursing home that were replacing 2 H B Smith steam boilers. The new boilers were started and after a lot of study I determined that the Engineer had not done his job correctly. The boilers were grossly undersized but that was only 1 of the many problems. With-in 2 weeks the water tubes of the boilers were burning out due to near 100% make-up water. The engineering company that did the specs for the system did not realize that the steam return system was deteriorated to the point that almost no water returned from the radiators. The boiler tubes that I inspected and cut looked similar to the picture from @heating help and some were completely plugged. All the tubes in both boilers had to be constantly replaced until the return system was re-piped. ( 2 Weeks to plug the tubes)! SAD

MRC · March 28

Dan, being retired since 2015 I want to thank you for letting me tag along with you! Mike

MGREGORETTI · March 29

A water meter should be installed on all boilers
This problem could have been located long before the boilers failed with a water meter.
In addition to all the water loss, the energy use must have been 3X what it should have been.
Its great that you installed the relief valve but sell them a water meter and a maintenance / monitoring contract to prevent future failures . The boiler business needs to focus on the environment and energy consumption. There is money to be made being green and helping customers avoid problems like this.
All the best for the holiday
MG

Boiler Failure After Two Years

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