Rotting from the top

john walsh_2

So. I'm just curious. The boiler sales rep tells me that he spoke to his engineer and they both agree that this boiler has rotted because of taking on too much new feed water over its relatively short service life of sixteen years. And I have no reason to disagree. but it does raise a question for me. How come This boiler only rotted at the inner top of the two outermost sections and not at the water line? The inner sections (to the naked eye) look brand new.

KC_Jones

Any answer is going to be speculation in large part.  My guess would be the turbulence of the boil was causing those areas to be affected more than the others, given they are end sections where the steam is exiting.

There are many factors, but the primary one is generally the amount of make up water bringing in oxygen.

Hopefully they fix the boiler piping and figure out the reason for the excess make up water. Was sizing verified with the replacement?

cross_skier

Your near boiler piping is not to standard but probably not the issue.  I am curious how much water you add per season and the pH of the water.

I saw a This Old House episode where the top of a newer Weil McLain. boiler rotted out so I guess it's not unheard of.

My 23 year old Pearless series 61 is still going strong.  I have not installed the VXT water feed but have spent a few hours tracking down small leaks over the years.  Its "double header" is similar to yours but each header services a different main.

ethicalpaul

Speculation: At the water line, the temperature of the iron is moderated by the sloshing boiling water. But up high it can get much hotter. That higher temperature combined with the oxygen that is getting released by the fresh makeup water might increase oxidation rate there.

john walsh_2

@KC_Jones
This is a boiler that was not closely monitored. It has an automatic water feeder so I don't have an answer. What you say makes a lot of sense. Regarding sizing of the new boiler, yes it was sized to the connected load. But so was the old one. Regarding the near boiler piping, Although it's definitely overkill having two three inch headers, I think that would only contribute to slowing the steam velocity out of the boiler and making drier steam.

john walsh_2

@ethicalpaul

Makes sense.

john walsh_2

@cross_skier

Yes. I thought that 16 years was a poor run. But in fairness, I'm sure that diligence was lacking regarding detecting leaks throughout the system over the years

EBEBRATT-Ed

@john walsh_2

Sadely in this day and age 16 years is not a bad run if the boiler is not maintained. It's not uncommon to see 6 or 8 year old boiler rotted out

pecmsg

john walsh_2 said:

@KC_Jones
This is a boiler that was not closely monitored. It has an automatic water feeder so I don't have an answer. What you say makes a lot of sense. Regarding sizing of the new boiler, yes it was sized to the connected load. But so was the old one. Regarding the near boiler piping, Although it's definitely overkill having two three inch headers, I think that would only contribute to slowing the steam velocity out of the boiler and making drier steam.

So all the radiators were measured and the EDR properly calculated?

cross_skier

I'm pretty sure 3 pass steam  boilers where the flue gasses stay under the waterline will last at least twice as long.  I am told almost all boilers rot at waterline or above.  

Intense heat against dry iron may be the problem.

Anyhow my next boiler will be the Megasteam with gas burner conversion.  I'm hoping that by then it will be manufacture option or at least well documented.

cross_skier

Looks like Slantfin Intrepid may be the only smaller 3 pass wet jacket steam boiler that is currently approved for use with a gas burner.

https://forum.heatinghelp.com/discussion/153026/new-slant-fin-intrepid-with-ez-gas-burner

If you are trying to avoid steam boiler rot this may be worth investigating

Hap_Hazzard

cross_skier said:

Anyhow my next boiler will be the Megasteam with gas burner conversion.  I'm hoping that by then it will be manufacture option or at least well documented.

You should be aware that the noise from the gas burner will take some getting used to if you're used to an atmospheric boiler. The efficiency is very attractive, but I'm not sure I'd want that much noise in my basement. I'll probably get a Peerless 63-04 when my 40year old 561 gives up the ghost, but I might consider a SteamMax, unless they show the same tendency to rot as the Independence series. The jury's still out.

cross_skier

Thanks for the noise warning on the gas burner.  I do like the 3" feeds and the 2.5" return on the Peerless 63-04. It is a solid choice.

But if the 3 pass Megasteam is going to last 40-50 years I will be ok with the basement noise.

mattmia2

Is that header arrangement a recommended arrangement? It looks like each riser has its own equalizer then the connection off each riser is tied together then tied to the main?

I think you are overthinking the rotting out thing, figure out the excess water usage and stop that.

cross_skier

I totally agree.  I kind of hijacked the thread and apologize. 

I am shopping for my next boiler.

I did find out in the last hour that the Megasteam is the only small 3 pass boiler where ALL of the heat transfer occurs underwater so it has the most potential to be extremely durable.

john walsh_2

pecmsg said:

john walsh_2 said:

@KC_Jones
This is a boiler that was not closely monitored. It has an automatic water feeder so I don't have an answer. What you say makes a lot of sense. Regarding sizing of the new boiler, yes it was sized to the connected load. But so was the old one. Regarding the near boiler piping, Although it's definitely overkill having two three inch headers, I think that would only contribute to slowing the steam velocity out of the boiler and making drier steam.

So all the radiators were measured and the EDR properly calculated?

Yes. That is correct.

motoguy128

I wonder if there was a lot of surging. So the water line at the outlet would drop, metal gets hot, then the water surges up and cools it…. Rinse and repeat with oxygenated water if there a lot of makeup.

Or, 2nd theory, water boils at the point of lowest pressure. the outlets would be the point of lowest pressure. So there’s a lot of steam flashing at that point combined with oxygenated water and high dissolved solid acting also an an abrasive. Added to surging.