That means they have iron content.
Originally Posted by kodo
Flat black is the worst color for radiating heat. White or silver is best and a gloss is better than a flat color.
Can't see the rivets in the picture and no, I have no clue as to who made them.
anybody know what kind they are? looks like some kind of pressed steel to me (notice the rivets).
Why do you care? If the house heats evenly and the rad's not leaking, why mess with it? On the other hand, if you're going to replace it, put the room or rooms to receive new heat on a separate zone and just do a Manual 'J' calculation to determine the needs of each room. Install heating elements to match and you're done.
how do i estimate the BTUs emitted by each section???
If YOU want change, YOU have to first change.
If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!