no heat travelling from one main pipe off boiler

ScottJ

We have a steam system ... had house for 20 yrs and never had this problem.... one of the main lead steam pipe off the boiler is stone cold hence 9 of our 18 radiators will not heat....  there are no vents on the radiators and it is a 2 pipe system... Ive called our oil company who has serviced the system and they said that he cant imagine why this is happening... ( but cant come out for a week)... boiler was replaced 9 yrs ago....  any ideas as to what is happening?  he said that we do not have steam traps in our system....

nicholas bonham-carter

suddenly-no heat!

if you have a 2-pipe system, with no traps, it is likely that you have a vapor steam system [the Cadillac of steam].

small valves, or orifices control the amount of steam going into the radiators, so that no more steam is admitted, that can be condensed. thus, only condensate will leave the radiator-not steam, therefore no traps are needed.

in order for the steam to get into the line, and the radiators; the air must be let out. i suspect that there is some sort of vent on the non functioning return which is not letting the air out. there could also be a sag in the pipe which pools water and prevents steam or air from moving easily.

if you can find a vent on the return line, tell us what type it is or take a picture. also examine the supply/return pipes for any sagging, checking it with a level.--nbc

Rod

Vents and Pictures

Hi - As NBC mentioned look for vents along the return pipe leading from the radiators on the problem main and also look along the problem main for vents. Vents could be located on the return line near the boiler and/or after the last radiator on the main. I've attached a picture of a main vent. This one is copper so has turned green. They will generally be this shape (bullet shaped) but may look like a can of tuna on its side and they may also be colored chrome or bronze (or could have been painted by a house painter)  Pictures of the piping around the boiler and of the radiator (inlet /outlet piping) is a big help. If there are any other "weird contraptions" on your steam piping take a picture of them also. All this helps us identify what type of 2 pipe system you have and give us a better idea of what the problem might be. Where are you located? We may know of a good steam pro that services your area who could help you.

- Rod