plugged riser?

jimmythegreek

here goes trying to explain this.  I have a large one pipe system, 40+ rads 400k btus gas WMclain steam.  I bought the building 2 yrs ago.  Previous owner was a friend so I know lots of the history of this 1900s bulding, 4 floors and basically one branch does a series of rooms up from basement to top floor, about 15 branches or so from main.  Anyway, I have 2 risers I been working on as of late, that had NO heat whatsoever.  After coming here I have added an antler of gorton #2s on each main, have low pressure guages, new Tstat, and cleaned gallons of sludge from system and got rid of the wet steam and have dried things out a ton.  Thank you to all the help here.  My problem is the 1 riser has NO steam on all 3 floors above the main.  Last week I went to top floor and unhooked the rad and muscled off the valve from the floor nipple.  Upon doing this a small amount of steam leached out.  I wiggled and tried repitching the pipe and presto, tons of steam.  There is a visible elbow beneath the floor with a 2 foot nipple to another elbow and then down to the rad Toff in the lower floor.(there are individual floor boards here w carpet so I can see easily with a board removal)  Now after this all three floors lit up and had heat.  I replaced the rad vents w new and had heat for maybe 2 days and now nothing again.  PART #2.  The other riser has heat on the first 2 lower floors but not the top floor.  This top floor rad comes off an elbow on outside wall and comes into the room about 5 feet.  It then Tees off and goes into 2 short nipples with 2 small rads (2 section!) on both sides of a doorway, one in a room, one in a bathroom about 2 feet apart if not less.  Rad in bathroom slightly heats occasionally, room rad doesnt.  Upon muscling off the valves and replacing both valves and spuds(they had crappy packings and both leaked due to worn threads) I had super heat in bathroom but nothing in room?  I repitched as much as I could go and raised up (saggy building) and had heat.  Next day no heat in room but some in bathroom.  I removed rads and undid valve in room and found standing water in the elbow in the floor.  I shop vac and presto steam.  Then next day no heat in room, better heat in bathroom.  If I shake rad in bathroom she gets super hot, nothing in room.  Now a few days later bathroom is super hot working normal, room has nothing.  In short, I beleive I have a bad pitch off the T in that room letting one rad heat the other blocked w water.  Im gonna open floor and attempt to repipe/pitch, this room has T&G floor boards, easy fix.  The other riser that has nothing all the way up will work if i shop vac the top floor and then heat dies out the next day.  I think line is full of rust or gunk.  How do I go about cleaning this line?  I thought about snaking w plumbing snake, and thought about removing valve on top floor and pouring steam cleaner boiler clean down the line.  Any advice or suggestions?  thanks in advance, sorry so long just wanted to be sure I got all the info in.  Some of the pros may come up w some great secret info.............thanks.

BobC

Settling

I'll bet there is a short horizontal run that is pitched wrong bestowing you with a water trap. the fact you can get it to work fine for a while indicates removing the water lets the steam flow.



An old building like that may have settled over the last 80-90 years. Maybe a 1/2 - 3/4" shim under all the radiators (both valve and vent sides) on that run will help, just check the pitch on each radiator as you go to see if you have to add a bit more under the air vent end. Be careful so you don't crack anything.



good luck,



Bob

jimmythegreek

did that

I did lift all the rads on the lines as much as possible and then repitched.  The one little line is def pitched the wrong way but my concern is the other riser has been lifted to the max the piping will allow.  There has to be corrosion or something in the line.  How do I go about it? chemicals or snaking?  any ideas