Steam Heat Conversion

drew_13

I am guessing you are converting from two pipe steam to hot water? If so why not do a mono-flow system with two proper sized mains with mono flow t's suppling each radiator.

Derek_13

Steam Heat Conversion - 1/2 Inch Return Pipe

We have a 2 pipe steam system. We are following all of Dan's suggestions on conversion in the article posted on your site. We are removing all piping in the basement and relocating the new boiler. We are going to zone the system into multiple zones - 1. Main Floor (4 rads), 2. Second Floor (5 rads). The existing piping to each rad on the first and second floor is such that the supply and return come back to the basement. My question is this. The return pipes coming back to the basement are 1/2 inch. The contractor wants to pipe each zone as a 1 pipe series loop. In reading Dan's article on steam coversion he talks briefly on small returns, I am concerned that the contractor's proposed piping system will cause to much restriction on the flow as you go down the loop. Your article mentions that a 1/2 inch line can carry about 15,000 BTuh, and cumulatively the rads in the series would put out more heat that this. I haven't done the calculation as to how much more heat and possibly this would be part of the analysis that needs to be done. However, I suspect that the rads down the line will be cool and not heating to capacity, leaving me with some cold rooms come winter time. Is this something I should raise with the contractor? Should I be considering the 2 pipe reverse return loop? Any suggestions would be appreciated.

klaus

black iron pipe

Actually for 1/2" black iron pipe you'd be closer to 20,000 btuh at 2gpm. That's figuring a 10 degree temperature drop across the radiator.

Series loop: verify the series loop itself is going to be larger than 1/2". The legs from the radiator to the loop only need to handle each rad's load requirements and the loop it's connected will need to be able to handle the entire load of the zone. For example one inch pipe could carry up to 80,000 btuh.

This may be plenty if you do a room by room heat loss and total it up by zone. Many of these old radiators were grossly oversized when installed as new. They had leaky houses with little or no insulation to overcome. Windows left cracked open at night, etc. Have you taken steps to tighten the building envelope?

Hope that all makes sense

Good Luck, Rich L

Tony_23

Loop

I'd do a "homerun" system. Completely balanceable and no downstream loss like a series loop.

Rob M

how would you do a homerun system,could you then run 1/2" to each rad.

Tony_23

Yes

Off a pair of manifolds. A "parallel" distribution system.