coils-btu capacity steam to hot water

creger.robert

have house with many in wall heating units with horizontal steam coils -want to convert to hot water looking for charts for btu capacities

Jamie Hall

The heat output of any radiator or convector is related to the area (referred to in steam work as "EDR" -- equivalent direct radiation) and the temperature. At steam temperature, the heat output of a convector such as you have is 240 BTU per hour per EDR. At typical hot water heat temperatures -- say around 170 or so -- it will be about two thirds of that. There are charts for this -- I can't find mine at the moment but someone will.

This is one -- but only one -- of the problems with changing steam to hot water. Unless there was a lot of extra capacity in the existing radiation, you will be cold.

There are other problems as well. There is the possibility of leaks, since hot water works at pressures up to 30 times as great as steam. There is conversion of the valves and removal of all the traps. There is rerouting or replacing most if not all of the pipes. And there is the necessity of a new boiler, of course.

Against which, there is little real gain. Steam is (or should be, if it is done right) quiet, has no pumps, has simple controls, and is very close in efficiency to the best (and most expensive) hot water boilers.

The bottom line? We generally do not recommend that a steam heating system be converted. Rather, we recommend that the system be gone over thoroughly and any problems corrected.