two (2) pipe steam radiators

bill_26

I have a radiator in my kitchen and another in my nook using the same feed and drain lines. The radiators only heat on about the top third of the radiator (fed from the top). The rest of the radiator is cold. I replaced the valves and the traps to no avail. I removed the radiators and blew air through them. There was a little water in them, but not much. When I hooked them back up, they worked for about a day (heat coming from the entire radiator) then back to the top third. They sit over a crawl space so I elevated the drain line sufficiently so it drains back to the boiler. Still nothing. All the other radiators in the house work fine. Does anybody know why this is happening and what I can do about it? I would appreciate any advices. Thanks.

Steamhead

Could be a couple things

Check the traps on the other radiators to see if they are letting steam into the dry (overhead) return. If they are, this will pressurize the return and some radiators won't heat well.

Also check the air vent on the dry return to see if it is working. If this vent quits, it can cause the same problem.

If you're not sure what you're looking at, take some pics and post them here. Also, have you located any manufacturer's info on the various parts of your system?

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