30 years of deteriorating pipes - 2 pipe steam

ProblemSolver

30 years ago - a library was added to this customers home, but the library was 3 steps down from the original home's floor level; so the heating company had to drop the steam and return lines about 27" in-order to get below the steam radiators they added in the library. (the library, and most of the house is built on a crawl) They were not careful about the pitch of both lines; thus, both lines have been holding water in pockets and the pipes have been rotting from the inside - out. I cleaned the boiler and sight glass about 2 weeks ago, and returned this last Friday to evaluate the system. I had to clean out the boiler and sight glass again!!
I told this customer, his problem began 30 years ago, and now the pipes are too rotted away to even think about servicing them. The only fix is to remove the library from the loop and put the piping back the way it was originally.
Here is a drawing of the two loops in the crawl space. The boiler is a Weil Mclain EGH105. There is actually one more loop for their green house.

jumper

Would have been easier to mount radiator on wall of library than dig tunnel?

ProblemSolver

I told the customer the library should have been constructed a step up from the rest of the house, instead of 3 steps down. It would have had a taller crawl space too. It's a belly crawl space now.

nicholas bonham-carter

They could have done a hot water loop off the boiler.
Those pipes have probably been in the sealed damp atmosphere of the crawl space, and therefore rotted from the outside in. I have been amazed at the interior cleanliness of dry returns, and supplies, where all maintenance was up to date.
It's a case of no oxygen-no rust. This is why a completely clogged steam radiator is such a rare occurrence. It is possible that in a bad new installation, the oily surging of a knuckleheaded system will fill some radiators with sludge. --NBC

ProblemSolver

This Boiler needs cleaning/purging once a week. That is how bad the lowered piping is. There are 5 very large column type radiators connected to that "lowered" piping. The piping for the 3 radiators in the library does not / has not have a good pitch, thus holding puddles of water and over the last 30 years the pipes are rotting from the inside - out. What I have not done in this trade, but need to do to this system, is get the mud/dirt out that has been traveling through all 3 loops because of this one rotting away loop. I sure can use some advice on the best way to approach a full system cleaning.

EBEBRATT-Ed

What's wrong with fixing the piping and installing a condensate pump? You can dig a pit to put it in

ProblemSolver

Two pipe system. Both have been dropped to a level that is not acceptable for the dimension A, and the installers did not keep a good pitch. For the steam line, it would have to be re-routed above the radiators which puts it running across the windows. A condensate pump for the return is OK. All-in-all, no good.