radiator size?

alan_8

Two part question. How do you determine the right size of the radiator for a room? On a one pipe steam heat system, if the room is cold, pitched toward the supply, vent not clogged and radiator barely heats or not at all, what would be the problem? Would tapping in another vent lower help? thanks.

Mike T., Swampeast MO

The size of the radiator is determined by the heat loss of the room. However the old-timers who initially sized your steam system (presuming it's old) didn't have the benefit of our modern computer-generated heat loss calculations and often used various "rules of thumb" for sizing. So, to keep a new radiator in an old system in reasonable balance you have to account for the way the system was originally sized.

I believe that the old "Mill's Rule" was quite common and I think you'll find it here in either "Hot Tech Topics" or "Heating Q&A".

You didn't say if the radiator was cold as well as the room. Or perhaps not as hot as other rads in the system...

alan_8

thanks- room is cold as is most of the radiator. some times the top part of the radiator gets hot. You can feel the heat down by the bottom/value, but it just doesn't seem to make it way fully into the radiator.

Mike T., Swampeast MO

Air vent on that rad might be undersized or defective. Hand valve on that rad may not be fully open or defective. Main venting may be undersized, defective or not present. Branch to that rad may be clogged with accumulated goo.

Have you tried removing the air vent when the boiler is firing? If you do and you gets lots of air and then steam, it's probably as simple as an undersized/defective air vent.

Do you have Dan's books, "We Got Steam Heat" and "The Lost Art of Steam Heating?". If not, get them!!!

Steamhead

I'd say you have a main vent problem

the main must fill with steam in about a minute. Then all radiators will get steam at about the same time.

Measure the length and diameter of your steam mains and tell us what vents are on them. We can tell you what you need.

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