De-scaling a steam boiler

thfurnitureguy_4

<<A surface blow off while the boiler is busy surging really seems to shorten the process of calming down the water level.
Ok I'm not sure of what a surface blow off is? Is this the same as skimming? The rest seems OK, thanks

thfurnitureguy_4

Boiler cleaning /de-scaling

My boiler has been run for years prior to me purchacing the building with leaking radiators and returns. So, lots of makeup water. After much repair My system is tight. My concern is with cleaning a Burnham v-905A. I have no King valves, so I assume the only way to build up the 5 lbs of pressure they call for in the blowdown will require the closing of all the radiator valves? I would guess this was never done. How much of an invitation for failyer is this to old pipes? of the 2 drains in the mud legs one gushes and the other is much slower. If I remember the boiler is calling for a 2" tapping for this? I have standard 3/4" boiler drains. Seccond,to clean, is vineger a good way to de-scale? If so what kind of gal/ gal of water do you use and do you boil ect. As always Thanks T

t. tekushan

descaler

I've used a couple of local products (Cleveland Ohio) like ScaleX and State Chemical's Acidine. You can usually find this kind of stuff locally at commercial supply houses. The products I've used have been (going from memory here) about 1 gallon cleaner to 30 gallons boiler water. Go to the boiler manufacturer's website to find what the approximate volume of water the boiler holds WHEN FILLED TO THE MIDDLE OF THE SIGHT GLASS.
There won't be any scale to speak of above the water line. The risk you run is that all of that fresh water brought in oxygen, allowing the sections to rust at the water line.
Soooo... THIS IS IMPORTANT: Use a descaler that is composed of inhibited phosphoric acid. The phosphoric acid dissolves scale and loosens rust but the inhibitor part prevents it from attacking clean metal.
The next thing is that you must really clean the heck out of the boiler after rinsing this stuff out. The boiler will surge like crazy if you don't get the PH back up above 7 (neutral). I've always found myself having to skim and blow down a number of times after several cycles of the boiler. A surface blow off while the boiler is busy surging really seems to shorten the process of calming down the water level.
I'll defer to other's judgement on whether it is really necessary to build up the 5 lbs of pressure. I've never done it since I'm prone to avoiding catastrophe on someone else's heating system. The descaling worked fine in my experience.
-Terry