Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

How do I unclog a return line on this 2 pipe steam system?

Stardance Member Posts: 23
The return line on this radiator is stopped up and prevents radiator from heating. There are 6 radiators on this line. Two before this one and three after. All 5 of those work fine and have new steam traps also. This radiator works fine if I disconnect the return line after the steam trap. This radiator is on the second floor of the house. What's the best way to clear the return line for this radiator?


  • pecmsg
    pecmsg Member Posts: 3,879
    edited May 20
    How can you remove the piping after the trap with removing the trap? (Just clarifying)
    Remove the ell on the right and run a threaded rod through it. If not blocked there remove the ell on the left and do the same. If not blocked their good luck!
  • Steamhead
    Steamhead Member Posts: 15,991
    You might try removing the trap, installing a hose connection on the return and flushing it out under street pressure. If that doesn't work, you'll have to take pipe apart.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • leonz
    leonz Member Posts: 779
    Another way would be to use a drain clog buster sized for a bathroom sink drain by removing the steam trap and attaching a reducing bell and long pipe nipple which would be used to hold the drain blaster in place and slide the drain clog buster in the nipple and use a garden hose to apply water pressure to the clog and flush out the blockage.
  • Mad Dog_2
    Mad Dog_2 Member Posts: 4,869
    Do you know for sure its clogged?  Thats very rare on dry returns.  Usually Air-locked.  Did u locate the Main vents?  Mad Dog 
    STEAM DOCTORJohnNYmattmia2
  • clammy
    clammy Member Posts: 2,912
    I would suggest first dis connect and see if you can blow through it w no restriction if there’s some restriction then I would suggest to disassemble the horizontal return piping from the return to where the vertical drop is ,I ve run into a few where there’s just a blockage of rust at the elbow going from hortizontal to vertical . Last one I ran into I was told they had used a air compress and the line was clear yet refused to heat ,I disassembled the dry return and found it jam packed w rust ,took a pic and sent to building owner ,flushed it out very well snake the vertical piece and reflushed ,fired her up and all was good . This is the best advice other wise you’re wasting your time .i highly suggest not to use a drain cleaning product it will possible clear it but who would add drain cleaner to a steam return not I said the tin man . Drain cleaner is what it says drain cleaner not steam return pipe cleaner it a cheap attempt which will usually garner no rewards and will definitely need to be complete flushed out a steam it would drastically alter the ph of the water in the boiler and possible cause excessive corrosion in any pipe that it is no to completely flushed out of . Just a bit of small advise
    Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
    Mad Dog_2Larry Weingarten
  • jringel
    jringel Member Posts: 11
    have you tried running the system with the other radiators closed just to be sure its not an issue with one of the other traps keeping the steam from passing through this radiator?
    John RingelEnergy Kinetics
    Mad Dog_2mattmia2
  • mattmia2
    mattmia2 Member Posts: 7,736
    It is possible to be clogged but far more likely that there is a pitch problem and it is trapping water somewhere(assuming all of the traps on the system really are working properly).