Sterlco Micro Series Water Temperature Control Unit - Manual (Page 36)

Page 36 MICRO Series Water Temperature Control Units
cable, especially at the entrance point to the unit. This inspection should be made by a
qualified electrician. Check for leaks, especially under the pump, as it may indicate a worn
pump seal.
6-2 Corrective Maintenance
Pumps and Seals
Before leaving our factory, we test each unit extensively, then we calibrate each
unit. Afterwards, the unit is drained and blown out with air to remove water from
piping systems. If the unit is allowed to stand idle for a long time before being
installed in your factory, the housing gasket at the pump can dry out and can
possibly leak when the unit is started. In most cases these gaskets will soon swell
and form a tight seal. In other cases, it may be necessary for you to tighten the
pump bolts to stop a leaking condition.
Pump seal surfaces can separate slightly because of rough handling or from
vibration during transit. This could cause a leak at the pump seal when the pump
is started, but in most cases the surfaces will mate again after the pump is
allowed to run for a short period of time. If they do not reseal, you may need to
open the pump and free the seal by hand. It is seldom necessary to install a
replacement seal in a new unit unless the seal has been damaged because the unit
was started without water.
Our pump seals have a long period of service life. Some conditions, of course,
can shorten seal life, including the presence of grit, operation of the unit without
water, sustained high water temperature, or presence of certain chemicals in the
water. Our pump seal assembly has been developed to resist abrasive particles
that are present in many water systems. This is done by a special flushing system
that uses water exiting the pump to constantly wash the seal area.
It is also fitted with high temperature flexible components for maximum heat
resistance. These same components remain flexible even at low temperatures.
Thus, the standard seal is a fine combination of heat resistant and wear resistant
components. Unfortunately, even under normal use, the seal will eventually wear
and require replacement.
A small puddle underneath the unit is a sign of rotary seal wear, and if
investigation confirms the pump as the source, the seal should be replaced as
soon as practical. The water slinger is intended to provide temporary protection
against this, but a continued and substantial leak will ruin the motor bearing and
cause further damage.
After the unit has been in service for a period of years where abrasive conditions
are present, you may find that the pump bracket (the top half of the pump
casting), can be eroded away in the area around the seat of the rotary seal. This
area should provide a straight, smooth bearing surface for the cup seal. Should
your casting show signs of erosion in this area, the casting needs to be replaced.
The replacement cost of the casting is very modest compared to the down time
and maintenance cost for frequently replacing the seal.
Under some conditions, the pump may not start. After turning off the power
supply, check the motor shaft to be certain it is free to turn. By removing the