Plugged closed loop riser

[Mastercylinder]

The risere are plugged in the closed loop they are sch80 I used to use compressed air but they are so brittle they burst when I use compressed air now I was thinking using a shop vac to try to suck the debris out any suggestions?

 

[TugboatEng]

Use an acid. Phosphoric acid is the most popular option. It won't weaken the system, it only removes wasted material. This may expose existing leaks. Don't conflate this with the acid causing the failure.

Do you have a plan to treat the system after it's cleaned?

 

[Mastercylinder]

I don't have access to the shot feeder, the building is managed by 2 management companies I only have access to the 1st floor, I used to treat the system, but the management company I work for sold the 2nd thru the 5th floor, the boilers are in the penthouse, the only time anyone goes in there is a break down, it's very frustrating, there are frequent power failures and all the crap in the closed loop gets stuck in the first floor risers and it takes me a week to get them cleared out, I have 1 thats plugged bad, no flow at all

 

[georgeverghese]

Sounds like you've got very poor quality boiler feed water that is corroding the tubes in the boiler and this dirt / rust / scale is collected up at the low point on the 1st floor.