Condensate Return Pumps
Condensate Return Pumps are used for returning the hot condensate back to the feedwater holding tank in the boiler room. Pumps are required to overcome gravity, pressure drops from long piping runs, and back pressures in return lines. Condensate Return Pumps are either electrically-driven centrifugal pumps or pressure motive pumps (PMPs) that use steam pressure as the motive force to pump the condensate.
Boiler Feed Pumps are always electrically-driven centrifugal pumps that are regulated by the boiler control system to pump condensate from the feedwater holding tank into the boiler.
Pressure Motive Pumps (PMPs)
Pressure Motive Pumps (PMPs) are pressure-driven pumps which return condensate back to the boiler room; using steam pressure as the motive force. PMPs can be supplied as individual pump – which include a pump tank, the internal pump mechanism, and a set of inlet and outlet check valves – or as a packaged system which includes the vented receiver tank (to collect condensate) mounted on a common base.
Models of PMPs are designated by both their Inlet and Outlet check valve size. For example a 3x2 PMP has a 3” inlet and 2” outlet. Increasing check valve size will increase overall pump capacity. Other factors that affect pump capacity are Fill Head height, Motive Steam Pressure, and system Back Pressure. The PMP pump tanks are available in either Ductile Iron, Carbon Steel, or Stainless Steel depending on Model.
Pump Tank Model/Materials:
PMPC = Ductile Iron
PMPF = Fabricated Steel
PMPSS = Stainless Steel
PMPNT = Ductile Iron or Stainless Steel
Complete Package System (PMPs with a Vented Receiver)
The installation of a Pressure Motive Pump (PMP) requires a vented receiver for initial collection of the condensate. The receiver volume must be adequate to temporarily store enough condensate during the pumps discharge cycle when the pump tank is pressurized with steam. Vent line size must be sufficient to properly vent the flash steam and maintain 0 psig inside the receiver. Vent line size is based on both condensate volume and condensate temperature entering the receiver.
Complete Packaged Systems are available. Simplex, Duplex, and Triplex systems include stand-alone PMP pumps with check valves and a vented receiver mounted on a common base. All components of the system are properly sized and pre-piped together; requiring only four connections to be made in the field. Duplex & Triplex systems can be used for increased capacity or in the event of a single pump failure
Electric Pumps
Electric Condensate Return Pumps are designed to work intermittently, discharging condensate only when the receiver tank is nearly full. This is accomplished with a float switch. Watson McDaniel electric pumps are offered in Simplex and Duplex models. Also available with control panels.
W4100 Simplex & Duplex with Steel receivers
W4200 Simplex & Duplex with Cast Iron receivers
W4300 Simplex & Duplex with Stainless Steel receivers
