Flushing of return lines

Jon Sobel

I have a 75 yr old house with a one pipe steam system and a new gas fired burnham boiler was just installed with an automatic water feeder. I was having trouble getting heat to the second floor radiator at the end of the line, and changed the main line vent and radiator vent with some success( still not great). While troubleshooting, noticed the water level was very high in the boiler, and drained it for approx 12 gallons (capacity is approx 4.5). The boiler installer advises that the return lines are probably cloggged and that condensate is being slowly returned and thus the water feeder is adding water to the boiler.

He suggested connecting a hose to the where the main air vent attaches and flushing the returns through the boiler. He said to remove the dirty water a bucket at a time from the boiler drain and flush till clear. I have several questions about this procedure.

Is it feasible to expect the flushed in water to travel down the return pipe as opposed to retrograde through the main line?

Do I want that old corroded water flushing through my new boiler? There is no flush out valve as described on this website. Are there any parts that need to be removed from the boiler before flushing, such as the LWC probe or pressure gauge?

Is there enough pressure from a garden hose to effectively de-clog a return line?

Can I fashion a new return line with PVC piping and does a return line need to be pitched back to the boiler?

If I can't use PVC, can I use rubber/clamps to attach a flush out valve in line, or do I need to thread new connections?

Any advice would be greatly appreciated.

Jon Sobel

Still looking for advice on flushing the return lines.

Thanks