Preventive Maintenance; Water Coil Maintenance - Zehnder Rittling VS Series Installation, Operation And Maintenance Manual

Preventive
maintenance
50

Water coil maintenance

Electrical shock can cause
personal injury or death. When
installing or servicing system,
always turn off main power to
system. There may be more than
one disconnect switch.
The installation and servicing
of air conditioning equipment
can be hazardous due to
system pressure and electrical
components. Only trained and
qualified service personnel
should install, repair, or service
air conditioning equipment.
Direct ground water
applications only
If the system is installed in an
area with a known high mineral
content (125 PPM or greater) in
the water, it is best to establish a
periodic maintenance schedule
with the owner so the coil can
be checked regularly. Consult
the water quality section of
this manual for a more detailed
water coil material selection.
Should periodic coil cleaning
be necessary, use standard
coil cleaning procedures, which
are compatible with the heat
exchanger material and copper
water lines. Generally, the more
water flowing through the unit,
the less chance for scaling.
Therefore, 1.5 gpm per ton
(1.6 l/m per kW) is recommended
as a minimum flow. Minimum
flow rate for entering water
temperatures below 50 °F (10 °C)
is 3.0 gpm per ton (2.2 l/m per kW).
All other water loop
applications
Generally water coil maintenance
is not needed for closed loop
systems. However, if the piping is
known to have high dirt or debris
content, it is best to establish a
periodic maintenance schedule
with the owner so the water
coil can be checked regularly.
Dirty installations are typically
the result of deterioration of
iron or galvanized piping or
components in the system.
Open cooling towers requiring
heavy chemical treatment and
mineral buildup through water
use can also contribute to
higher maintenance. Should
periodic coil cleaning be
necessary, use standard coil
cleaning procedures, which
are compatible with both the
heat exchanger material and
copper water lines. Generally,
the more water flowing through
the unit, the less chance for
scaling. However, flow rates over
4 gpm per ton (4.3 l/m per kW)
can produce water (or debris)
velocities that can erode the heat
exchanger wall and ultimately
produce leaks.
Filters
Filters must be clean to obtain
maximum performance. Filters
should be inspected every
month under normal operating
conditions and be replaced when
necessary. Units should never be
operated without a filter.
Washable, high efficiency,
electrostatic filters, when dirty,
can exhibit a very high pressure
drop for the fan motor and
reduce air flow, resulting in poor
performance and/or nuisance
trips. It is especially important
to provide consistent washing
of these filters (in the opposite
direction of the normal air flow)
once per month using a high
pressure wash similar to those
found at self-serve car washes.