Return water too cold- crack the boiler?

Feb 22, 2006 24 Replies

OK, I've heard this, and at the moment may be a victim of it.



My Weil-McLean boiler appears to be leaking, so sayeth the service folks. They believe its got a cracked boiler (they can't get the side panel off because the hot water tank is right next to the boiler).



How prevalent is this as a problem?



Could running the water through the boiler backwards help to cause this problem?



The circulator pump doesn't have an arrow on it, but I'm pretty sure its pumping water into the top of the boiler, and out the bottom. This would be bass-ackwards, would it not?



Dave



Just turn the boiler upside down and keep the piping the same. This should cure everything. Bubba

Thanks for sharing your limitless knowledge.

Fucktard.

Dave

Update- on a 43 deg. day (today) there was a 30deg. temp drop feed-return, spec calls for 20.

The previous owner assed a bunch of other stuff up, I bet.

D

Bubba's a big swingin' dick over at alt.hvac, he can take it.

D

That may be backward but it would induce less stress on the tank because now the coldest water is not directly entering the hottest part of the boiler (bottom). I would expect thermal stress cracking to occur if you poured very cold water into a very hot section of the tank (which should not happen if the tank is filled) The leak is probably due to age and rust like is common in a residentail hot water heater

That only says that your boiler lacks the capacity to heat your home efficiently. What are the absolute temps. If water is coming out at 80C and returning at 50C. That would not induce a temperature stress crack. Low efficiency could be accounted for by a thick buildup of scale (lime or rust) in the tank. Can the tank be purged, have you ever?

Have they measured the pressure of the inlet water supply? Is the pressure relief valve on the boiler functioning properly (excess pressure could have bulged the tank and cracked a seam). Are there obstructions in the water loop reducing flow rate and increasing outlet pressures at the pump head?

PipeDown, I don't know what the absolute temps are, and if this boiler gets replaced (as opposed to a section replaced) I'm going to be very involved to make sure the right boiler goes in, not just a same-for-same replacement.

I moved in this past May, don't know if its ever been purged. I do know my water is fairly hard, and still haven't cleared up issues involving the water softener.

This leak started immed. after a full service/cleaning, and everything tested OK. After the service the relief valve dripped, and I though that was causing all the water on the floor. It wasn't, the valve was leaking and the boiler was, as well.

I do know that the boiler typically has 180 deg. F at 10-15 lbs pressure, according to the guage on the unit.

The service co. could not fully remove the outer shell because of space issues, I checked with them and they OK-ed me (from the potential warranty perspective) to go in there with the nibblers and cut the sheet metal covering to expose the leak, so we can see what's actually leaking.

Thanks for the input, and on a few more things to check.

Dave

wrote

Well that'll f****ng GUARANTEE that it will work properly!

You a GOTT DAMN GENIUS!!

I wish I could get you to come to all of my jobs and make sure they are right!

Just from reading your original post, you don't know WHAT the f*ck you are doing! And you are going to make sure you get the right boiler??!!

Go ahead. Stand right over top of the person that's installing your equipment. They'll just LOVE you and your "expertise"!

F****ng moron....

"Red Necjerson" wrote

Red NecJerson?

What are you? A Southern Swede?

Last week you were Red Neckerson. I guess rednecks can't spell...

;-]

Excuse me you stupid, m**********ng, daddy's-c*ck-sucking, best part of you ran down your mother's leg piece of s*it, but the service co might just assume that whoever installed the thing previously had done the goddamn calculations (that's assuming the bastard that owned the house didn't put it in himself), and if I ask the co "what size SHOULD go in" that is hardly standing over them.

Being involved and asking questions is not the same as strutting around and 'supervising'. I was a professional mechanic, and I know what that's like.

There's a big difference between an involved customer that wants to understand what's going on, and someone that's telling you what to do (service rate is double for the latter group).

You are another alt.hvac retard, ain'tcha, that needs to s*it on people to make themselves feel big, so tell me, how's that working out for you? You feel big now, you f***er? Gonna head on over to alt.hvac and tell 'em how you flamed an arrogant stupid thinks-he-knows-it-all ho-moaner? Well, go have fun, scooter, and remember if you keep the beer warm ain't no one gonna want any so you can have it all to youreself, on those rare occaisions when someone actually visits your fleabag sour-stink-of-failure singlewide.

So GO F*CK YOURSELF and head back to alt.hvac and flame the homeowners who mistake it as a group of and for dedicated professionals, as opposed to the pissy little playground for the disgruntled retards that you and others like you have turned it into.

Dave

S*it, apologies to Red there, I thought he was an alt.hvac retard, turns out he's an equal-opportunity retard across many groups. So where I put alt.hvac just read whatever group you like to go to, whether it be home repair or cigars...

Red, you should go to alt.hvac you'll fit right in.

Dick.

Dave

The old "I serviced it and now its suddenly broken" scam. Seen it happen to many an automobile, especially when you clean the carb.

probably knocked the chunk of lime scale that was plugging an ancient leak loose when you purged the tank. Given the entirely unknown service record, its safe to assume, it has never been maintained.

Might be SOL.

I understand, Due diligence is not the same as micromanagement. Just let the guy work in peace once you make up your mind - right.

Spam,

If you're saying that the boiler water is at 180 deg and the return water is at 150 deg then no, the return water did not "shock" your tank into leaking.

Dave M.

Exactly. Cold water shock would be if the water from the street is 40 or 50 degrees it can cause problems, usually over some time. That is very unlikely in a closed system. Industrial steam boilers that run at 300 to

350 degrees are typically fed with water that is about 220 to 225. Yes, they can crack when fed with 70 degree water.

PD, I don't *think* they purged it as part of the service- it wasn't on the invoice, and they didn't mention doing that.

They had trouble getting the cover off, but when I went home it was 4 screws and the section of cover came right off.

There's a crack in the front section of the boiler, on the side, just above the cast-in boss for the upper-right hinge pin for the burner door/assembly.

With the unit not running it looks like a pinhole, soon as it fires you can see its a 1/2 inch or so horizontal crack. It does show evidence of having been a slow leak for awhile, not enough to drip but wet enough to rust a fair amount.

Dave

This is really excellent writing. I may make it into a text file, and insert it into emails when words fail me. Well done!

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