Cracked Boilers

JohnB62

The new steam boiler was installed 5 years ago. Worked great untill outside temp dropped into single digits. Then the block cracked. This scenario has repeated itself 4 times in the last five years. The old ancient boiler never had an issue. This is a very large, very old house with 33 radiators. Some radiators are freestanding, some are recessed sunrad type, all are single pipe. They all work fine when the system is operating. The boiler header supplies a giant loop with wet returns, and there are several drops from the header to the returns along the very long runs to either side of the boiler. The professionally installed boiler by a very knowledgable qualified company is a slant fin intrepid with a beckett afg oil burner, and they can't seem to figure it out.

The msnufacturer has been brought in to this as well, and still no answers... How do we stop this reoccurance of a cracked boiler every year?

Jamie Hall

Something is very seriously wrong there, and you haven't gotten to the root cause of it. Has this been the same make and model boiler each time?

I'm glad you are getting the manufacturer in on this -- I hope on good terms. I'd be looking at some aspect of the installation of the boiler causing restraint. We usually think in terms of the piping configuration, and that can cause it -- two or more risers, or even just one riser and the equalizer, with no swing joints, for instance, but it could also be something about the way the block is supported from the floor, as it must be free to move with only one point of support anchored horizontally (other points of support must be there vertically and with uniform loading, but must be free to slide horizontally).

Hard to say.

STEAM DOCTOR

Was heat off for significant amount of time? Possible that boiler water froze and cracked the boiler? Or maybe boiler was super cold and when heat went on, the thermal shock cracked the boiler? Opposite of putting cold water into hot boiler?

STEVEusaPA

You had 5 cracked boilers in 4 years. Probably should've started seriously investigating after the 1st or 2nd time.

EBEBRATT-Ed

I am with @STEVEusaPA
on this

Steamhead

Slant/Fin is a stand-up company, in our experience- unlike some others.

Where is this job located?

What model Intrepid?

Post some pics.

nicholas bonham-carter

Where was the block cracked-bottom, middle, or top?
Has there been a water meter on the system? Were there any LWCO shutdowns from time to time?
Was the boiler functioning normally otherwise after installation,-pressure low etc?
Without having seen the piping, and only with the statement, “replaced a very big old boiler”, I am going to hazard a guess based on a similar experience.
If there are any long horizontal elements in the returns, which are now not well below the waterline, (but instead slightly above it), they can suddenly hide the water, and almost empty the boiler, when the pressure rises. When the boiler stops firing, then, with the pressure drop, the water suddenly returns, putting the metal into thermal shock.
If that is the case then it is surprising that the boiler lasted a year each time!—NBC

JohnB62

JohnB62

Pressure set at less than a pound?

JohnB62

JohnB62

The piping has been checked by both the installing company and the manufacturer and has been deemed correct

JohnB62

JohnB62

Same boiler make and model each time.

JohnB62

JohnB62

Returns have been partially replaced and are pitched well to the boiler.

JohnB62

All components are working properly.

Lwco and auto feed have not lost power.

JohnB62

The system runs fine during normal weather.

The problem occurs when the temperature falls into single digit territory.

JohnB62

I do not fully understand why the system works fine then has the problem based on outside temperature.

A call for heat is a call for heat on the inside, and the temperature inside is consistant when the system is operating.

pecmsg

JohnB62 said:

When was the boiler in a flood?

JohnB62

after it cracked. this home is way up in elevation, no flood zone here.

EBEBRATT-Ed

The Hartford loop looks too low but it may just be the picture angle

JUGHNE

Just a long shot here, but is it possible that the floor under the boiler is unstable?
Could it be settling and having the boiler hang on one riser, putting uneven strain on the block? The strapping on the header looks to be cutting into the insulation.

Here we have ground heave and recede from frost. The reason footings are set below the frost line.
But it seems that you are no where near ground frost.

Also we have ground water that recedes and returns, as if the ground is slightly breathing.
Just a WAG.