Posted by Tom Brown on September 12, 2001 at 02:34:22:
Need help with a job in which I have installed qty 8 HVAC fan coil units with steam heating coils and chilled water cooling coils. When in the heating mode, the fan coils make a loud "clicking noise" comming from the steam coil. This noise comes and goes while the units are running.
The boiler feeds steam to these eight fan coils through one large steam valve. There are no individual valves at the fan coil.
While in the heating mode, you can feel the steam coil is hot at the steam inlet, but as you move your hand across the coil, it cools down. The coil is a 1 row coil.
All the fan coil units are tied into one room thermostat, so as long as the thermostat is calling for heat, the system steam valve is open.
Even with the thermostat in the heat mode, and with the steam valve open, you can feel the steam coil cool completely down, which would indicate that there is no steam flowing through it.