Two Radiators Don't Heat In System

Dale

Sometimes with a 2 pipe system the problem is in the trap of the rad that's getting hot not the one that isn't. I would shut the inlet valves to the other "good" rads and see what happens. If your problem rads get hot one of the steam traps on the ones that do get hot are leaking through and putting steam into the return. Or you could change the trap element in all your traps and start afresh. If you have cross over traps in the basement they vent air and should not pass steam, change them also. Good luck and let us know what you find. If you want a supply test on the bad rads take out the trap element and shut off the inlet. No steam should come up out of the bottom of the trap piping, If the inlet valve works and you are a little bold, leave the element out and let the steam in, if the rad heats right up the problem has to be in the return.

J_9

Two Radiators Don't Heat In System

I have a two-pipe steam heat system that isn't heating properly and I've checked the steam problems faq here and I've had a Holohan devotee out to my house and we still can't figure out the problem.

Here's the issue. Two of the upstairs radiators on the system only heat approximately one third of the way down the radiators. One of the radiators is a massive one and the other is a small bedroom heater. The massive radiator is the very last one in the entire system, but the bedroom one is next-to-last on one of the steam lines (coming out of our boiler there are two pipes, one goes one way for one half of the house, the second pipe goes another direction and heats the other half of the house). For clarity we'll call these two lines "massive" and "bedroom" in relation to their problem radiators.

No other heaters on the massive line have this problem save the massive one. The bedroom line has one more radiator down the line after the faulty bedroom radiator. This last radiator on the bedroom line heats perfectly, but the preceding radiator, the bedroom one, heats one third of the way.

We've tried adjusting the pitch, we've checked the incoming steam trap valve and we've checked the condensate outflow trap. All the incoming lines are clear and all the outgoing lines appear clear (we even blew two carbon dioxide cannisters down the outgoing pipe to make sure there wasn't a plug of some kind). We've tried throttling back the downstairs radiators so the boiler would fire longer. We've turned the thermostat up to 85 to make the system run longer. When the thermostat is up, the massive radiator heats 2/3rds of the way down and the bedroom heater heats all the way down like every other radiator in the house.

You can see why that option won't work.

With the downstairs radiators throttled back, there is no upstairs improvement and the downstairs always feels colder than normal. Our thinking here, when the radiator guy and I put our heads together, was that pressure wasn't reaching the massive radiator before the others were fully hot and bringing up the temperature downstairs where the thermostat was. We thought if we cut back on how much steam the downstairs radiators got then we could get more steam pressure upstairs before the thermostat cut in. Didn't work.

I plunked down $200 and there's been no improvement so I thought I'd pick the collective brain trust here for any ideas whatsoever.