John F. Kennedy High School

The condensate receiver/vacuum pump located in the pit did not appear to be holding or pumping condensate. Additionally, both vacuum pumps were running constantly and failing to pull a vacuum. After isolating different portions of the system to try to find the vacuum leak we removed a plug from the top of the pump to see if we had suction. Upon removing the plug we found no vacuum and noted the pump was empty and had lost its prime. An adjustment was made to the water level control for the vacuum tank to solve the issue and help the pumps maintain their prime. SMI discovered that the vacuum in the boiler room was sucking all of the condensate out of the receiver preventing the tank from maintaining a vacuum. In order to stop the problem the boiler room vacuum pump upper limit was reduced. After multiple adjustments SMI was able to get both condensate receiver and vacuum pump sets to satisfy the vacuum switches and pump condensate normally.

While troubleshooting the vacuum pumps a cold call came in for room 108. It appeared that the coil was flooded and was confirmed by cracking the union on the steam trap. To determine if the cause of the problem was related to the steam supply/condensate return system or contained within the UV itself SMI went into the crawl space. When a blow down valve on the strainer below the room was opened, steam immediately poured out, which indicates that there was steam supplied to the unit. A union was then cracked on the return side and there was an immediate vacuum showing there was no condensate back up on the return side. This is pointing to an issue within the UV.

Mepham High School

The reported problems all reside in one corner of the building. The steam supply and condensate return for each room is piped in a riser formation coming up from a single steam and a single condensate main in one crawl space. The condensate main from this area drops underneath the floor to reach a single condensate receiver/vacuum pump. It was observed that the receiver tank had an abnormally low temperature and after approximately 20 minutes of observation the condensate pump had not run at all. As a result, the piping configuration of the return system was investigated, which led to the determination that the condensate line from the problem area drops below grade and then has a lift in order to enter the receiver tank.

When this piping configuration is used there must also be an overhead line or “dry line” to break the vacuum or allow air to vent. Without this line minimal condensate will drain as it becomes partially air bound and cannot make it through until enough pressure builds to overcome the airlock. Another issue is that vacuum from the pump set cannot adequately transit the flooded below grade line to make it to the devices on the other end. To verify the potential issue a plug from the return side was removed from the end of the line drip trap in the problem area and there was little to no vacuum on the line.