# Rotten old boiler



## futz (Sep 17, 2009)

Back in late December I got a leaky boiler call. Went out expecting the usual pinholed expansion tank or something similar. This is what I found:

I get there and it's an old Allied MG100. The blue return fitting is leaking from two out of three connections. Things look pretty grim, so I warn the homeowner that things are very likely to get very expensive very soon. He says go ahead...










So I take it apart to see what the problem is... and find this. :whistling2:









What used to be threads are now coil springs. :laughing: Non-oxygen-barrier Poly-B heat loops have done their magic once again and corroded everything ferrous, including the crappy steel boiler, down to tin foil. Sigh...










Flashlight inside the nipple. You can see right through the threads. The pipe is paper thin.









HO decides to get a second opinion, pays me for my time up to there and gets someone cheaper to replace it. I didn't want the nasty little job anyway.


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## droptopgt (Dec 17, 2008)

Does boiler flushing or chemical treatment help prevent corrosion from the poly b pipes? Almost identical damage happened at my inlaws. A new heat exchanger alone was around $700 vs $3500 for an all new boiler setup. They went the all new route.


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## ShtRnsdownhill (Jan 13, 2016)

if you use the proper pex with oxygen barrier in it, you wont have any problems like that..


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## futz (Sep 17, 2009)

ShtRnsdownhill said:


> if you use the proper pex with oxygen barrier in it, you wont have any problems like that..


No kiddin!? :laughing: Ya, I know. Switched to oxy-barrier loops many, many years ago - probably sometime in the 90's.

It's about twenty-some years too late for this house. No homeowner ever is very interested in blasting out all their floors (and some of their walls) and replacing the heat loops and the floors. The proper fix at this stage is to isolate the loops from the rest of the heating system with a stainless heat exchanger. Works pretty well, though it is a bit expensive.



droptopgt said:


> Does boiler flushing or chemical treatment help prevent corrosion from the poly b pipes? Almost identical damage happened at my inlaws. A new heat exchanger alone was around $700 vs $3500 for an all new boiler setup. They went the all new route.


I think chemical treatment *might* slow the corrosion down some if you re-treat the system religiously every couple years. 

Boiler flushing, on the other hand, is probably the worst possible thing you could do to an old rusted boiler. When you flush you clean out all the (protective?) muck and put in fresh oxygenated water for a fresh burst of corrosion on old thin metal. It's a terrible idea.

But even a steel boiler lasts a good 25 years with non-oxy-barrier loops, so it's not *so* terrible to have a worn out boiler at that age. A cast iron boiler probably lasts even longer.


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## Tommy plumber (Feb 19, 2010)

Top picture shows polybutylene crimped to copper. I even see the old plastic fittings. Wow. Is there a lot of PB installed where you are?


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## paultheplumber1 (May 1, 2014)

I run into it once in a while. Never have I seen it on heat though. Mostly mobil homes and home run systems. I have one customer who still thinks he's going to see some money in the class action suit against vanguard. He's got 3 baths and I think only one has all 3 fixtures working.


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## futz (Sep 17, 2009)

Tommy plumber said:


> Top picture shows polybutylene crimped to copper. I even see the old plastic fittings. Wow. Is there a lot of PB installed where you are?


Yup, crappy acetal fittings. When PB was new I remember us stopping using those horrible things very quickly (in the first six months to a year) and switching to brass/copper fittings. Had too many failures on new houses. They're such trash.

There is tons of old PB out there still. It's gradually getting replaced during renovations and after failures, but there's a lot of it that just keeps on working and never gets noticed.


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