I just moved into this 100 year old home (and in great condition for it's age). Came with a Galaxy GXHA-120 EDPZ previously installed. Here are some specs to give you an idea:
Fuel Type: Natural Gas
Steam Pipe Insulation: About 65% of the visible basement pipes are covered. I look in my crawlspaces and seems like all in there are covered (asbestos of course...
Please note: this is a one-pipe steam system
I live in Pennsylvania and now that the weather is really starting to kick in (Highs in the teens and less), I have three radiators that are acting up
RADIATOR#1 (doorway entrance): Located on the first floor about 12 feet from furnace in the basement. Wouldn't warm up, so I gave it a little more slope and boom, nice and hot
RADIATOR#1 (1st floor living room): Located on the first floor about 18-22 feet from furnace. Same issue, gave it a little more slope and it fired up. There is a similar radiator in the same room without any issues.
RADIATOR#3 (1st floor bathroom): Located about 35-40 feet from furnace. Changed the airvent on this one and worked for about 3 weeks, then dead. Take the airvent off and only the first cell get hot. Put the vent back on, the whole thing goes cold. Not even an aggressive slope toward main did anything.
Apart from adding a slope toward the main on all three radiators, I have switched out variable airvents from other working radiators with the airvents of the radiators that don't work. The radiators that didn't work remained not working and the good rads continued to work despite the different airvent.
When I manually down the thermostat or the furnace turns of cause it reached temperature, the main pipe for RAD#1 and #2 suddenly gets got (just the pipe, no sections). But RAD#3 remains dead.
I'm eventually going to call an HVAC tech, but i've gotten a good handle on things and have been able to fix many issues already, but this is one that has stomped me. NOTE: My house is 3,680 sq ft. with 14 RADS. I can post the rad types if helpful (size etc..)