Steam coil detail

Brad White

their recommended piping hook-up arrangement in their literature. A Wing VIFB coil is piped differently than a so-called freeze-proof side-piped coil. Those with face and bypass control may differ from those with steam valve control.

I assume that this is 2-pipe steam.

For valve control this is what I like to see in order of steam flow:

Gate or ball isolation valve, wye strainer, eccentric reducer to control valve size, nipples and union to control valve, both sides, increaser to coil connection size, tee for vacuum breaker, tee for pressure gauge. A flexible braided metallic pipe connector is a nice thing to do to avoid expansion stresses and vibration.

If the load is large enough, I like to split the control valve into (2) parallel valves, 1/3-2/3 capacity. This allows the 1/3 capacity valve to act as a "base load" valve and to reduce freeze risk while the second valve fills in as needed.

On the outlet (condensate) side, I like to see a full-size dirt trap at least 6" deep below a tee. The tee branch goes to the trap assembly consisting of a gate valve, optional wye strainer, nipples and unions to the trap and on both sides, trap outlet check valve and gate or ball isolation valve. A flexible braided metallic pipe connector upstream of the last isolation valve is also a nice thing to do.

If face and bypass damper control is used, the detail is similar except a single control valve is most often used. It stays 100% open when it is below 38F outdoors to minimize freeze risk and the FBP dampers do the controlling.

Mike K.

Steam Coil Detail

Does anyone have a good source for a generic steam coil detail. I have several air handlers that will have steam coils for heat. Smaller applications 1000 to 3000 cfm. Conection to LPS and condensate.