guts of a marsh boiler return trap (with pics)

moneypitfeeder

So now that the heating season seems to be over (knock on wood), I've decided to slowly start tackling the problem of condensate not returning to my boiler in a timely fashion. This is my second year in a house with steam heat, and with research I've determined it is a Marsh Vapor system. The Boiler return trap has not had water in the sight glass since I've moved in here, and the piping (near boiler and returns to the trap/ air eliminator) are most definitely wrong. Before I give up and throw in a boiler feed pump, I'm going to try to resurrect the beast. When I got the piping to it removed, and pulled the top housing off, (very nice of Marsh to attach all moving parts to the housing) it was all caked in what I can only describe as red clay. And it very well could have been clay, my house flooded at least to the first floor in 72, and our soil around here does have clay. This will be a painfully slow process, I'm a homeowner, not a pro, but if you'd like to follow along I'll keep posting pics and status updates.

icesailor

Crud in traps:

Is your house on a well?

If your house is on well water, and you are getting fines in the water and you aren't filtering it out, if you are adding water to the system, you could have what you seem to have. But if not, I can't imagine how that stuff got there.

I once saw a building drop 12" over time when they dug a cellar in clay and water. They put in 12" of crushed stone and poured the cellar floor on top of the gravel. Because of the water, they put sump pumps in the cellar to lower the ground water. The flowing water allowed the clay fines to be pumped out of the clay and into the storm drains. They had sump pits for the pumps. If you looked into the pits with a flashlight, you could see something simmering. Then, the 4" drains that carried the water away became totally blocked with a talc like silt. Like what your fittings look like.

Have you ever tried boiling off some water until it is gone to see what is left?

I/we need more info.

Steamhead

You won't need a boiler-feed pump

Change the Pressuretrol to a Vaporstat and set it for a maximum of 8 ounces or so. This will keep the boiler pressure from getting high enough to overcome the "B" dimension.

moneypitfeeder

no dice

We've got city water, and from what I can tell it always has been. As far as I can tell the system was installed circa 1925, from then till the 70s I don't know how many boilers the house went thru, and in the 70s it flooded, and I think the house might have gotten a new boiler then. I'm guessing they abandoned the return trap and air eliminator in place. The system works, i.e. there is heat to all rads, it just takes over an hour to get heat to them and the water takes a long time to come back to the boiler causing my lwco to kick on and add water while its running, and then it is almost flooded or actually flooded if its off for awhile (several hours) till the water returns. I know the near boiler piping is wrong I have no header/ or equalizer, and the Marsh return trap even if it weren't ceased up is piped wrong now with a shorter boiler, the measurements don't match what the manufacturer called for. I'm slowly making progress on her, I added new Gordon vents to both my mains up on antlers 15" back from the end and 6" up, added insulation to the mains where the old asbestos was removed, installed a vaporstat and low pressure gauge. Next up after cleaning up the boiler return trap and air eliminator if they can be saved will be adding a drop header to dry out the steam, and possibly all new wet returns (some areas are really looking corroded, and if I can see corrosion I can't imagine how much of the wall thickness of that pipe is left). Then possibly lowering the return trap to meet Marshes' specs with a modern boiler. If you look in the library the diagram is there the guys at Marsh Steam were nice enough to dig up a schematic for me

moneypitfeeder

hope?

In your opinion would you try to make the return trap/ air eliminator function as advertised if you could? or should I just leave them abandoned? I did just this morning get my vaporstat in, still took a very long time over an hour for the water to return to the boiler and my system never climbed over .05 psi

Steamhead

Of course clean it out

and also the two check valves in the piping below the Return Trap. Make sure the water can flow freely thru that piping.



When you start up the system after putting it all together, feel the steam line going into the Return Trap. It shouldn't get hot right away. If it does, you've found the problem- the Return Trap is leaking steam into the return lines.



The system will work fine with the Vaporstat and no Return Trap or check valves. But if you want, I believe Tunstall can rebuild the Return Trap... www.tunstall-inc.com .

moneypitfeeder

new pics

Well took apart the air eliminator today and acid dipped both assys. Now they don't look they they just came out of the titanic. They're soaking in penetrating oil till tomorrow when I'll try to disassemble the return trap mech and get all the pivoting action working smoothly again. We have definitely reached the point where my husband thinks I'm nuts.

crash2009

That acid dip

 looks like it cleans brass and copper very well.  Is that a process you do yourself or do you send it out?

moneypitfeeder

Diy job

I just used a half gallon of muriatic acid I had left over from cleaning concrete. You can get it at most hardware stores. (note, only if the part to clean is all metal and no plastic or gaskets etc) It is nasty stuff so use precautions, well ventilated, respirator, gloves, goggles etc. and be sure to neutralize it before disposal. At this point I've got all the bushings reamed and pins polished up and everybody is free floating. the return trap is sitting on the floor, and I'm digging crud out of the elbows to the check valves.

patrick linhardt

change out the wet return

From water you describe, you have a clogged wet return, which is very common for a circa 1925 system. Please see pic of wet returns that built up crud on the inside through the years. Your water is taking an hour to return because of the build up in your wet return.

moneypitfeeder

been there

Already pulled all the lines from the traps to the boiler, between the float mech being seized and the return elbows being clogged I can see why condensate was not returning. I haven't gotten to pulling the long length of wet returns from the end of mains to the traps yet, I'm contemplating running copper for those. But my husband had opened those last year when looking for a leak and they appeared to be clear of obstructions and free flowing (in the area of the leak). The only reason I'm considering rerunning the wets in copper is to reduce the possibility of crud buildup and to raise them off the floor about 1" since we are in a flood zone, and I occasionally have a small bit of water that enters the basement near the walls (and don't want iron sitting in a tiny pool of water rusting away). Thanks for all the replies!

patrick linhardt

anything under water

The crud will build up in any portion of the piping that is always under water, which is any piping below the waterline of the boiler, what is termed the wet return.

The wet return is pitched back to the boiler, so the crud will naturally follow the pitch and accumulate the most at the lowest point. It can also build up anywhere there is a turn in the pipe, an obstruction on the inside, etc.

It is OK to use copper pipe on the wet returns, but not on the steam carrying portions of the system.

niftyc_2

did it work in the end

Dear moneypitfeeder, did cleaning the air eliminator work in the end? (Were you able to return it to functioning?) I'm thrilled by your cliffhanger story, as I am contemplating cleaning my dunham air eliminator as well. Christian

niftyc_2

clarification

EDIT: To clarify my question, I saw your follow-up post here: http://www.heatinghelp.com/forum-thread/137940/Ive-got-heat-again but you say the jury is still out on whether cleaning the air eliminator worked in the end.

moneypitfeeder

Not quite as advertised

Sorry it took me so long to reply. I don't think my system ever builds a vacuum, so I wonder if maybe that's part of the problem. I did not lower the return trap/air eliminator to the dimensions that the diagram shows to my new water line, so the return trap never fills with water. I did a test where I timed the how long it took for the first floor rads to fill with steam, first I ran the test with just the air eliminator as the return vent to get a baseline for that. (Before attempting I verified all my rad traps were working so I knew I would not have live steam in the basement) Then I ran the test with the the vent on the eliminator completely removed and just as a open 3/4 pipe. Big difference much faster heating, in order to get the same timing, I added 4 Gordon No 2s in the return line that feeds to the eliminator. Now my rads start heating basically immediately when the heat  hits the risers. We are having a real cold snap, and my house is comfy and warm.