Condensate pumps are used in situations where the condensate returns cannot be
returned by gravity. The condensate is pumped into a condensate return tank with the pump located in such a position as to allow for gravity flow into the
Pumps are also used to re-circulate hot water in heating applications. These
pumps are sized to establish a predetermined flow rate between the boiler and space conditioning.
Centrifugal pumps, as the name implies, operate on the principal of centrifugal
force. A driver, usually an electric motor, spins an impeller increasing the pressure of the liquid and delivers this pressurized liquid to the pump casing.
Here the liquid is collected and then directed to the pump discharge nozzle for use in the heating system.
Centrifugal pumps may have one of two types of casings. A volute type casing collects water and discharges it perpendicularly to the pump shaft. A diffuser type collects water from the impeller and discharges it parallel to the pump shaft.
Boiler Pump Maintenance
To properly maintain these pumps, there are three areas that should be
addressed. This includes the lubrication, seal replacement and alignment.
Lubrication is probably the most important part of your pump maintenance program. Begin with checking the manufacturers recommended schedule for
lubrication and use the lubricant that they suggest. Keep detailed records on when you lubricated the pump. Make sure you record the suction pressure, the discharge pressure and general conditions that the pump operates under. Is the pump hot? Do you hear noises? Record it all so that you have a base line to
compare against in the future.
Proper alignment is another area that needs to be addressed. Alignment is more critical in higher rpm applications. Use a dial indicator if your pump is running at 3,500 rpm. For those of you running at 1,750 rpm a straight edge and
taper gauges will do the trick.
Replacement of Seals
The last area of maintenance is the replacement of seals. Whenever you replace the seals make sure that you replace all the items and not just one part. Inspect the seals and try to determine why they wore the way they did. If there
are grooves in the seals, this could indicate that there is a high level of suspended or dissolved solids that need to be addressed.
Be very careful when you replace the seals. Do not touch them with dirty hands and be especially careful not to damage them when placing them on the shaft. Also be careful not to scratch any of the machined surfaces that will result in a leak path.
Visit our Boiler Pumps Page for more information.