XII. FREEZE
PREVENTION
P
ROGRESSIV
T
UBE
®
collectors are virtually freeze proof throughout the Sunbelt area of the
country due to their thermal mass and heavy insulation. However, the pipes leading to and from
the collector can freeze. Collector piping should be as short as possible and should penetrate
the building as close to the conventional water heater as possible to minimize exposed runs of
piping. Exposed piping or piping in unheated attic spaces must be insulated with a minimum of
1½” wall insulation. It is extremely important that all piping be installed to slope a minimum of
¼” per foot of pipe run to ensure proper draining during severe cold weather. The following
table is a guide to the hours required to freeze solid ¾” type M and type L copper pipe that has
been wrapped with Armaflex/Rubatex pipe insulation of various thickness.
All systems must have a manual drain down capacity as discussed in the System Plumbing
section and shown in the System Plumbing Diagrams. A recommended option for all systems
installed in areas that experience freezing conditions in an automatic freeze prevention valve
such as the Eaton/Dole FP-35. The valve should be installed according to the manufacturer’s
recommendations (
and Drawing L)
on the
return solar loop piping between the collector and
the roof (consult the System Plumbing Diagrams). A swing type check valve must also be
installed on the return solar loop piping to prevent short circuiting of the freeze prevention valve.
Thermostatically controlled pipe heat tape can also be used as a freeze prevention measure for
the piping.
Because contractors have greater knowledge and experience of their local winter weather
patterns and conditions, it is their responsibility to decide if a freeze prevention valve or heat
tape is necessary for the system.
In northern climates, the collector should be shut down by draining during any months that
average or exceed 1,000 heating degree days. The collector should also be drained whenever
severe freezing conditions exist, below 10
0
F with overcast skies. Good performance can be
expected from P
ROGRESSIV
T
UBE
®
systems during daytime conditions of clear skies and cold
ambient temperatures. It is
most important
for local contractors to realize it is their
responsibility to use the most appropriate and reliable techniques necessary for their area to
prevent freeze damage to their customer’s piping or collector.
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Summary of Contents for PROGRESSIV TUBE
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