forced air coils in a one pipe system

Brad White_9

You have two competing principles here, mass and less mass, coupled with the cyclical nature of steam.

Steam is fine for reheat in a two-pipe or district steam system provided that in a two-pipe system the pressure can remain constant within a range.

With one pipe steam, traditionally applied to cast iron radiators, the radiator mass allows the space heating to withstand the pressure-based cycles of the boiler.
Copper tube/aluminum fin coils will heat and cool practically instantly between these cycles. The chances of those cycles coinciding consistently with your space requirements for reheat are threefold: Slim, Fat and None.

Remember, the cycles are needed with one-pipe steam to allow the air back in to allow the condensate to flow back to the boiler.

With two-pipe steam, district steam or other on-demand source, the pressure can be maintained constantly and allow the condensate to have their own path back to the source.

I would suggest a water system off the boiler below the waterline, with a plate exchanger to keep things simple. Truly.

Dave Grabowsky

forced air coils in a one pipe steam system

I am installing a 10 ton forced air cooling system with steam reheat int an existing one pipe steam system.There will be 4 steam coils with capacity of 33,000 and 50,000,and 57,000 and 88,000 btuh.How do I control this system. I realize that I cannot have a metering device at the inlet(or can I?) because it will restrict the steam condensate.This will have the condensate running counterflow to the steam.I am planning to provide a coil with an enlarged opening at the bottom to allow the flow of steam/condensate. I will also have a tapping at the opposite top far side of the coil.I was thinking that I would install some type of air emmitance valve to regulate the steam.I don't think that this will work because it will not stop the steam from entering only slow it down. I may need cooling on some zones and heating on the others.Also it will not be fast acting enough to provide the full heating or cooling when required.
Will some one tell me how I can regulate these coils to operate off of a wall thermostat to provide the necessary heating or cooling when it is required?