Inconsistent heat

BigBus33

I'm new to steam we just moved into a 1920s colonial. Everything seems to work ok except 3 radiators (coincidentally? All on the 2nd floor front wall) don't heat up. It's a one pipe system and the valves are all open. I just checked tonight and the pitch seems ok. Could there be any blockage in the pipes causing the lack of flow? The house was unoccupied last winter - could this factor in? One room seems to get a little bit of heat but my 2&4 year olds who share the room are waking up with cold ears in the am. We just got a glimpse of Boston winter and when the real thing comes, more than their ears will be cold if I don't figure this out.

nicholas bonham-carter

cold as charity

most cold room problems are because the main air vents are not working in the piping coming back to the boiler. this may be because they are too old,under too much pressure, or just not there. if the air is not able to escape, the steam cannot get into the radiator to warm it up. can you look on the pipes coming back to the boiler, and tell us if there are main vents?--nbc

BigBus33

Main valves

The other 10-12 radiators work well. Would this be the case if the main vents are the issue?

nicholas bonham-carter

cold radiators

i am thinking that these are on a separate supply main, which is having venting problems. can you trace out the pipe which may feed risers to these three. there may be a sagging line, which is trapping condensate, preventing the air from getting our, and steam getting in.

you could carefully make a test with someone at the boiler switch.

switch the boiler off, let cool, remove one of the air vents

turn up the thermostat

have your assistant turn on the boiler

observe the movement of air from the vent hole, by holding a tissue in front of it.

turn off the boiler, let cool, and reinstall the vent.

if there is air movement, then it is a main venting problem, if no movement, a blockage/sag.--nbc

MrDvorak

radiator vents?

I had the same thing in my 1930s colonial, two of my radiators upstairs were cold. It was bad radiator vents that would not let air out / steam in. I unscrewed one of the bad radiator vents for a few seconds during a heat cycle and the radiator got warm almost instantly. If that does not happen, there must be a plug somewhere between the boiler and the radiator.