Pilot light can crack a steam boiler?

duke_john

Sunday I checked the low water cutoff for a steam boiler in rental property in anticipation of winter.  It did not work when the float dropped.  I talked to the tenant, who told me that he noticed this all last winter (after I checked that it worked properly before the last heating season) and he kept adding water as needed.  He did not inform me of this, or last year I would have called the utility company with whom I have a service contract.



The utility company came out today, Tuesday, and said that the boiler is cracked because the pilot light was on with a low to empty water level.  The water level I left while testing it was enough to drain the boiler through the low water cutoff valve but no other drain valve was open.  The boiler did not show any signs of leakage all year, it isn't a piezoelectric pilot light and the water feed is manual. 



Could the pilot light flame heat the boiler enough to form a crack with a low or empty level, or was my careless tenant the more likely prospect?



Could this be repaired without replacing the boiler?

ed wallace

pilot lite and cracked boiler

Yes in my opinion it could happen that the bboiler runs low on water and pilot light can heat the cast iron to the point when water was added it cracked as to fixing the crack can't be fixed time for a new boiler as to blaming tenent it's not his boiler most tenents do not tell the landlord about issues until it's a major problem

ed wallace

pilot lite and cracked boiler

Yes in my opinion it could happen that the bboiler runs low on water and pilot light can heat the cast iron to the point when water was added it cracked as to fixing the crack can't be fixed time for a new boiler as to blaming tenent it's not his boiler most tenents do not tell the landlord about issues until it's a major problem

duke_john

oh, no!

So I take it that the pilot light can heat it up to the point of boiler failure but only if water was added.



The pilot light needed to be shut off, with the boiler allowed to cool, before water was added, right?  So the utility service man may well have done the damage when he came in to check it out.

Steamhead

I'd say it's a stretch

a pilot light generally doesn't produce that much heat. 

nicholas bonham-carter

Who is to blame?

In my opinion, for a pilot light to crack the section, the boiler would have to be completely dry, with the pilot located improperly under the section, instead of under the passage between sections. Sometimes the pilot supply can supply too much pressure to the pilot and make it burn too hot.

It seems that the tenant was having to add water during the last heating season, otherwise how would he know the lwco was malfunctioning, possibly there has been a slow leak, which has now got worse. Can you see that the crack is close to the pilot?

As you change out the boiler, add up the radiator capacity so you are certain the replacement is the right size, and make sure the installer follows the mfg's piping diagram at a minimum.

Lastly, take the handle off the water feed valve and put in your pocket to check it and add water yourself. If properly installed, with no steam leaks, it will not need much make-up added.--NBC

TomM

cast iron

while I am no expert on the subject:

The critical temperature of cast iron (the temperature where a recrystallization change would occur) is 1330F.  Once it hits that temperature, it undergoes a crystal structure change to become an austentite, while the surrounding unheated iron is still ferritic.  When it cools (usually too fast) the heat treated area is now very hard, and is a different crystal structure than the surrounding metal, and it is prone to cracking.   

http://steel.keytometals.com/articles/art112.htm



Do you think the pilot light heated it up to that temperature when the boiler was empty?  That's your call.   Otherwise, i'd fill it up and see if it leaks.