Flushing Old Boiler From Relief Opening

Wcurtis

Is flushing from the top through the relief opening (valve removed of course) an effective method of interior cleaning?

My old boiler has one 1/2 drain that’s easily acceptable (one is welded closed overtime), this past fall I ran a borescope into this drain and it appears sludge is present on the floor just below the drain (hard to tell due to excessive moisture fogging up lense)

If a wand can be placed down the relief opening with a rotating head maybe the sludge can be thinned out enough to drain out the casing although it could take awhile.

Worth it?

Or is it better to backflush from the inlet side with a water hose in an attempt to flush out through the casing drain?

Long Beach Ed

Whichever way disrupts the usual flow of water should disrupt the sludge. Then lots of water will carry it off.

Wait until summer. Don't mess with unnecessary work during heating season.

If this is ancient, leave it alone.

pecmsg

(one is welded closed overtime)

Its there for a reason. Replace it and clean the boiler properly.

Wcurtis

extremely uneasy about attempting this plug removal as many years have passed before purchasing this home with sub-par upkeep and a lot of rust on the cap/threads, no attempts to remedy anything in my post will occur during the heating season

pecmsg

https://forum.heatinghelp.com/discussion/comment/1829682#Comment_1829682

3/4" is removable. Difficult but doable. Even if the threads get damaged it easy to chase new threads.