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Wet Return:Replace?

vaporvac Member Posts: 1,520
Firstly, I'd like to apologize for putting all these questions in separate posts, but as a homeowner, I felt it might make it easier to find an answer to a specific question, without it being buried in a long post.

My wet return is so clogged I don't even know how I was getting any heat. It's truly a testament to the robust and elastic nature of these systems and the old boilers. However, I know these new SF TR50s won't be as forgiving.

So...do most people replace the wet returns or just clean them out? If replaced, what type of piping should be used and how large should it be? If I can just clean it out, how does on go about that.

I'm attaching two pics to show them and their clogged remains. Really, what is this sludge? Most people only seem to want to show the beautiful new system, but I'm really getting into how grotty it all was.
Two-pipe Trane vaporvacuum system; 1466 edr
Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF


  • Jamie Hall
    Jamie Hall Member Posts: 23,272
    I'm following your adventures

    with considerable glee and delight -- you are writing an epic for us all!

    On the wet return... if you have a handy way to get into it (them?) at one end, and empty the water into something convenient at the other end, something which doesn't mind getting a little grubby, you can probably just flush them out with a hose.  They do get a remarkable amount of gunk in them... mostly iron oxides of one kind or another.  They usually look a lot worse than they really are.

    On the other hand, you can replace them and, in the process, provide nice convenient cleanout plugs and T's here and there as needed.  Furthermore, you can replace them with either copper or black iron, as you please.  Black iron is a little more elegant, in my view -- but entails a good deal of threading usually.  Copper is just fine, though, anywhere below the water line of the boilers (but not above!).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    I found out I had to replace my wet return in November.

    That's not a good time to find that out, especially when most of it runs behind drywall. Fortunately I was able to patch it up to make it through the winter, but I was nervous. The trouble is, it rusts out worst at the threaded ends--where the threads cut halfway through the walls--and if you try to replace one part, the stress on the pipes can break the next weakest joint in the system, even if it's 20 feet away and behind a wall.

    If you have any doubts about the integrity of the pipes, April is a much better time to start thinking about replacing them than November.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Rusty returns

    In retrospect, after Hap's story, I probably would advise replacing the returns rather than flushing. They could be run in copper, more easily than iron pipe, and will not be a source of future problems. Put in some full port ball valves to enable any flushing which may be needed in a few years or so.

    Here is a thought on the subject of an auto-self-skimming port:

    If the skimming port would be connected with a vertical pipe to the returns, with a tee and ball valve, then all the oily water will collect in that vertical pipe at the same level as the waterline. Six inches below that waterline height the ball valve could be opened to flush out the crud floating on the surface. If during any firing, one percent of the surface oil is thrown into the skimming circuit, then after a couple of weeks, all of the oils will have been trapped in that pipe, ready to be drained out. Because the bottom of the skimming circuit is connected to the return, the pipe will never fill, and overflow it's oily contents back into the boiler.

    Since you will have 2 boilers to clean, this would double your advantage.--NBC
  • vaporvac
    vaporvac Member Posts: 1,520
    Brilliant Idea!

    HH, thanks for giving you experience. I'll probably replace as it will make it easier to run into the new boilers as well.

    NBC, Brilliant idea on the auto-skim port. I'm going to have to diagram that out see if I'm understanding you correctly. Thank you.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • vaporvac
    vaporvac Member Posts: 1,520
    Could you draw me a picture?

    Could you draw me a picture NB-C, take a pic and attach as a pdf? I've been trying to wrap my head around this. It's sounds ingenious so i don't know why it's not done. I would be most appreciative.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • MDNLansing
    MDNLansing Member Posts: 297
    Clean Out

    If its feasible you can tap into the house water supply and pipe it into the end of the return to help with clean outs. On the boiler end of the return, use a valve to isolate the pipe. Just before the valve install a clean out of some kind (T with a boiler drain, or T piped into a floor drain). On the non boiler end of the return, plumb in a pipe feeding fresh water. When it's time to lean it out, close the valve, open the drain, turn on the water and flush until its purging clean water. If you really want to keep it clean, you could use a Y on the supply line to allow a garden hose to be used as well. This would let you flush with hot water from the WH as well. Keep in mind code might require a check valve on the water supply.
  • Auto skimmer?

    Here it is. When the pipe is connected like this to the return, the oily water splashed up into the port will remain there with the oil on the surface in the vertical, and never overfilling as the level remains at the boiler waterline. Once a month when the LWCO is flushed, the skimming valve can be opened as well and all the surface oil will drain into a bucket.

    One great advantage of the drop header, is in its separation of more oily water from the boiler, and there should be a valve in the equalizer to drain any accumulation off there as well. If 5% of the surface oil is trapped in there every firing! over a period of time, all the oil will be removed.

    Looking forward to receiving your email when your installation has finished.
  • MDNLansing
    MDNLansing Member Posts: 297
    2nd Valve

    This is great idea! Thanks for sharing this.

    Would it be advisable to add a second valve below the skim port valve so you could still manually skim and isolate it from the return?
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