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[dexterdan]

I have an outdoor wood boiler that I have used about 10 years.  I shut it down a couple of weeks ago and now I have an interesting situation.  Water and brown slime are coming up out of the water vent pipe at the top of the furnace and dripping down the roof of the unit.  I have checked and double checked that no new water is getting into the system.  My only guess is that the slime is actually growing and expanding in the boiler.  Has anyone else ever run across this problem?  Any ideas on what it could be?
Thanks.

[RSI]

Do you have a sidearm or plate for DHW? Any chance it failed and it passing water into the boiler?
Not sure about the brown slime. it is think or just rust residue or something like that?

[MattyNH]

Could it be the yrs of a mineral build up(iron for example) from your water? Rust?..Do you keep up with the water chemicals?..

[dexterdan]

I do have a loop for hot water.  I don't have a way to isolate it, but it is worth checking.  If that failed I could be crossing my boiler water and my domestic water.  I will admit to not putting in chemicals/conditioner last fall.  I think I will drain the system, check the hot water loop, fill it up again with new chemicals and see what happens.  Thanks for the ideas.

[artbaldoni]

Slime sounds like biofilm. Bacteria that grows in the water. You might want to check into a biocide like they use for cooling towers for HVAC. I don't think the regular stove treatmens have the biocide. That biofilm is nasty stuff and can harbor Legionella. If you are draining the system wear a dust mask to avoid any splashing water mist from getting inhaled I know blah, blah,blah, but a good friend of mine is now at 50% lung capacity from working around cooling towers.

[RSI]

Slime sounds like biofilm. Bacteria that grows in the water. You might want to check into a biocide like they use for cooling towers for HVAC. I don't think the regular stove treatmens have the biocide. That biofilm is nasty stuff and can harbor Legionella. If you are draining the system wear a dust mask to avoid any splashing water mist from getting inhaled I know blah, blah,blah, but a good friend of mine is now at 50% lung capacity from working around cooling towers.

I was just reading about Legionella and wikipedia says temperatures above 158 degrees will kill it instantly. Unless the boiler has been shutdown for a while that probably isn't likely to be in there.

[artbaldoni]

You are correct 160 F kills them little buggers. But I shut it down a couple of weeks ago and now I have an interesting situation. means low temps for a couple weeks. Probably not likely, but I thought it was worth the mention.

[DmdJoe]

I have an outdoor wood boiler that I have used about 10 years.  I shut it down a couple of weeks ago and now I have an interesting situation.  Water and brown slime are coming up out of the water vent pipe at the top of the furnace and dripping down the roof of the unit.  I have checked and double checked that no new water is getting into the system.  My only guess is that the slime is actually growing and expanding in the boiler.  Has anyone else ever run across this problem?  Any ideas on what it could be?
Thanks.

If it smells bad it is aerobic bacteria. Dump it and rinse it out. Check out your system to make sure you do not have any underdeposit corrosion. Metals will rust under bacteria.

If it does not have a really bad odor, it is probably bacteria, rust, and debris. Dump it.

Which either one make sure to inject a corrosion inhibitor chemical program to passivate your metals and all will be fine.

[victor6deep]

Has anyone dealt with this on a regular basis or do most users flush the system every 2-3yrs?

[slimjim]

Obviously it needs to be drained, I would do a water sample and have it checked to find out what it is that is causing it, and then find out if it has affected the heat exchangers, better to clean and repair now than in the middle of January.

[Scott7m]

Has anyone dealt with this on a regular basis or do most users flush the system every 2-3yrs?

Certified labs a co we deal with says its probably a good idea to drain every 3-4 years and start over in case anything is settling out of the water