Last two days I had a small VAV system to fire up. 6 VAVs with HW and a two heat/cool VAV RTU. Figure I would start with the VAVs to make sure all the dampers are open before messing around with the RTU.
First VAV. Nothing special until I get to the checking the hot water valve. Some tiny JCI actuator on the valve I'm not familiar with but its clearly a 0-10v actuator. Step one, I need to sort out is 0v open or 10v open. Coil is valved off by the manual isolation valves. Rather inconvenient. Pull the actuator off, cycle the signal just to see if it even moves and it does. Linear action that pushes on the valve stem. Actuator works, still don't know which way is open. Decide to slowly open one of the isolation valves in series with the valve. Turns out the control valve was open and I can hear water going through. Second later its pouring out of the strainer someone left the cap off. Well that's kinda odd. For giggles I put the cap back on and slowly let the coil fill up. 15sec later, I can hear it leaking inside the duct. Well we must have a frozen / burst coil. Kinda a big blunder to have that happen. Whatever, close it back off and move to the next VAV, and the next, etc.
All six coils are valved off. Some with enough water damage to the tile, ceiling grid and drywall that its clear several of the coils have burst. Wow, large space and there is no secondary heat except for a stretch of fintube along the exterior walls. Go to check that valve, sure enough its also valved off. Not messing with that at this point.
Clearly something has gone seriously wrong with this system at some point. VAVs done, lets see what this RTU has to offer. Get to that, disconnect is off. Flip it on and the supply fan starts instantly. Seen this story already on every other unit that has a VFD on the roof. Open her up, yup more of the same. VFD failed, so it was replaced with three wire nuts and left as is. Now the full picture is coming into focus. That VFD bypass also bypasses the freezestat, smoke detector and any other safety in the unit. Its disconnect straight to the motor basically. Whatever, carry on. Well nothing in the unit is power up besides this fan. Turns out the control tranny is also burned out in the unit. Power for the course at this point. Hearing the air noise near the unit, have to wonder if the duct work is still intact. Enough of this, we're done.
End of the day finishing up silly UHs, CUHs, etc on small DDC controllers. Least 50% of them have one issue or another. Tons of them valved off. Wondering how the hell nothing freezes (well besides the VAV coils) and I get to the sprinkler / water main room and find this little guy protecting it from freezing. Yup, also valved off.
- Sprinkler Room UH.jpg (2.38 MiB) Viewed 1079 times
Total dumpster fire. One of the worst off memory.
