3.1.8 Storage Tanks.
Check that the drain valve on the storage tank opens and closes properly without
leaking. Look for leaks at the piping connection between the valve and the tank.
Tank insulation must be complete, dry and properly jacketed. If foam insulation has
been applied to the exterior, make sure it is still in good condition.
If the tank is buried, take tank-top temperature readings one hour after the end of a
solar collection day and again the next morning. During that night, bypass the tank,
so any temperature loss is through the tank wall and insulation, not to a load. The
overnight loss of heat on a properly insulated tank will typically result in a
temperature loss of less than ten degrees Fahrenheit.
Unscrew and inspect the sacrificial anode in steel tanks with glass linings. The pipe
dope used by the manufacturer makes the rod difficult to remove the first time. After
inspection, clean this dope off the threads and use teflon tape. This will make
subsequent inspections easier. Attach a note to the tank indicating condition of the
anode and the date of the last replacement, if known.
Replacement of depleted anode rods is critical to the lifetime of a storage tank.
Fittings and Piping
Check all fittings for leaks and evidence of corrosion. Insulation on piping must be
complete. Insulation jacketing, if used, must be intact.
Sensor and Sensor Wiring
The previous section contains information on checking the sensor on the tank.
Make sure the sensor wiring is protected from physical damage and is kept at least
1 foot away from 120V wiring and at least 2 feet away from 240V wiring.
If the tank has a back-up electric element, be sure the sensor and back-up element
wiring are separated by at least one foot.
3.1 INSPECTION PROCEDURES