Boiler percolating

BobSers

Customer has a Small Slant Fin cast iron boiler attached to an old gravity radiator system with large pipe diameters, two pipe reverse return. Boiler is twenty years old and started percolating. In my experience this only happens when a system has a leak and feeding make up water. No leaks here. What cleaning solution to use to mitigate the deposits? I'm thinking of flushing like a tankless water heater with something a bit stronger than vinegar. Thoughts? Percolation sound telgraphs through the piping and is loud at first floor radiators. Boiler temp is below 180.

Jamie Hall

Almost certainly scale buildup in there. I do steam, so I have no idea what -- besides vinegar -- might work, although I do know there are a variety of products out there.

JUGHNE

If this has an open top expansion tank at the top of the system that could be a source of oxygen introduced into the system.

GBart

Is it percolating or thumping, we had some SF boilers that had funky castings and they trapped air inside the water jacket, there was no way to get it out. As the boiler ran it started thumping like drums, it reverberated in the chimney and upstairs, changing the block was the only recourse.

In your case, an old gravity system hooked to a small boiler, you may have cleaned the pipes into the boiler and filled it with mud, mud doesn't transfer heat well and takes a lot more btu's.

ch4man

GBart said:

Is it percolating or thumping, we had some SF boilers that had funky castings and they trapped air inside the water jacket, there was no way to get it out. As the boiler ran it started thumping like drums, it reverberated in the chimney and upstairs, changing the block was the only recourse.

yep, saw that twice about 3 years ago or so

lchmb

had my own boiler do that.. bottle of 8 way and quiet as a mouse...

ChasMan

I used the Rhomar water treatment in my Slant Fin. The product was Hydrosolv 9100. I ran it for a month and then flushed it and ran it again for another month. I did a 25 to 1 mix. It did not fix it 100 percent but 95 percent. I suspect the noise now is bits of stuck scale, stuck in passages. You need to put your ear against the jacket to hear it.