CB corrosion issue

[dlabrie]

I have a 10+ year old Central Boiler, CL 4436 That has developed a pinhole leak in the fire box side wall. I assume it is from corrosion. I have not used any chemicals in it for over 8 years. It is connected directly to my FHW oil system in the house. The CB is elevated enough that my system in the house runs at around 12psi.

Can I assume that I am corroding the system in the house as well? ( I installed a new Buderus cold start boiler in the house about 5 years ago) After I weld the leak in the CB, would testing and adding chemicals be advised? Would I be better off adding a heat exchanger between the two systems? Any advice would be helpful.

Thanks,

David

 

[maple1]

I think I would do both - HX & treatment for the OWB. I think I have read of CBs or at least OWBs of some brand springing leaks even when treatment was regularly used. I would be quite concerned about my Buderus (and the rest of my indoor system - pumps etc.) if it has been exposed to open water and a rusting OWB, unprotected, for 5 years - I seem to also remember reading somewhere about leaky Buderuses. Which is also kind of worrying for me since my parents also put a new Buderus setup in about 5 or 6 or so years ago - although it is closed & pressurized.

Hopefully you can get the CB fixed - think some have also reported there not being enough good metal to weld to, once they got at trying to get it patched up.

 

[BadgerBoilerMN]

The minister has it right.

Buderus will void the warranty of any "open" system, as they should.

We always isolate conventional boilers and radiation from outdoor boilers used a SS plate heat exchanger.

We also insist on system flushing, cleaning and dosing with the proper inhibitor. In a closed system this should last a lifetime, for open systems annual chemistry treatment is the bare minimum.

 

[OH_Varmntr]

Is your CB unit properly grounded via ground rod?

 

[warno]

That's no good. I can't say about the rest of the system but I can tell you how I would go about fixing the hole.

Drain the boiler down, obviously, then take a drill bit about 3 times larger then the pin hole and GENTLY drill into the steel, do not punch through. You just want the drill bit to cut into the steel to get penetration for the weld not make a bigger hole. Take a grinder and again gently clean the surface around the hole, you don't want to go gouging the firebox walls since you are already questioning their integrity. Then do the welding to fill the hole. Personally I would grind down the reinforcement on the weld then put a small plate over the area and weld all the way around the plate. Just to be sure it doesn't try to pop back open. Then fill it up and give it a day to check for the leak.

Good luck with the boiler. Hope you get it fixed up.

 

[dlabrie]

Is your CB unit properly grounded via ground rod?

I don't remember them installing one but i'm not sure.

 

[OH_Varmntr]

If there isn't one installed, you should do so. It will bleed off any voltages not meant to be there that contribute to electrochemical corrosion.

Also, is this leak right where the return water is introduced back into the water jacket? Could also be the turbulent water washing out the steel in this area. I'm assuming it is internally baffled, but cannot be sure for obvious reasons. I've never seen the insides of the CB water jackets.

 

[mike van]

Rust never sleeps it's said - That one hole there,. there's probably 20 more right on the verge. When it's drained, i'd do a little sound testing with a hammer, unless someone shot a hole in it, it's not the only spot.

 

[OH_Varmntr]

It may not be corrosion at all. It could be erosion. I'm interested to hear the location of the pinhole in relation to his return port on the outer water jacket shell.

 

[dlabrie]

It may not be corrosion at all. It could be erosion. I'm interested to hear the location of the pinhole in relation to his return port on the outer water jacket shell.

It wasn't by the feed or return. It had also bulged out a bit where it was leaking. We tried to pad weld it today with no luck. Tuesday we are going to grind it smooth and weld a 3X3" plate over that.

 

[Buzz Saw]

Is 3x3 big enough?

 

[maple1]

Hope your scraping & tapping all around the whole firebox while you're in there.

 

[dlabrie]

Is 3x3 big enough?

I thought so. It's only a pinhole leak.

 

[dlabrie]

Hope your scraping & tapping all around the whole firebox while you're in there.

I am actually pretty frustrated with the whole ordeal. I think it might be time to look at a new system. I sent a query to Econoburn to ask what they would recommend.

 

[OH_Varmntr]

Not to be a you-know-what, but by not running any water treatment chemicals in it for "over 8 years", you were just asking for this type of outcome.