Blocked Hot Water Radiator Return Line

[Joe Jor]

Howdy gang!
I have a 100 year old house in NY.  After draining the hot water radiator system over the summer to replace a number of values, I was able to represurize the system without leaks.

Once the heat started being used this winter, the tenant reports that a single radiator that will not get hot; all the other radiators work perfectly.  I called a plumber out.  He diagnosed that the return pipe is blocked.  His suggestion was to rip out the plaster walls to trace the pipe to either replace the piping or determine the location of the blockage so it can be addressed.

This sounds very drastic and expensive to me.  Has anyone heard of another way to jar a blockage loose?  The pipe is a 3/4 inch; there are no drains on individual radiator runs in the basement ... only a master drain for the boiler.

Joe

[Jim K.]

@Joe Jor

Thanks, Joe. Here's what I would try for this: drain the radiators on the third floor. Buy a basic 25-foot 1/4 in. drum plumbing auger for drains, here's a link to one:

Basic drain auger

Disconnect the radiator on the return side. Cut the thicker augering element off the auger with a hacksaw or a disc on a rotary tool, use pliers to stretch out the next three or four spirals of the auger spring line. Feed the 1/4 in. auger line into the return line. You should be able to feel if there's a blockage and if there is, you should be able to auger through it with the auger modified as I've described.

You've done a lot of work on this system, replacing all the valves. You clearly understand how this thing works. If the solution I've described doesn't get you anywhere, yes, the next step is busting out of the line and replacing it, but let's cross our fingers.