Dissimilar metals in contact may create galvanic corrosion at the site of contact, or
in soldered joints throughout the system. The most common example of this is
when galvanized pipe hangers or perforated strap directly contact copper tubing.
The resultant galvanic action corrodes the solder out of the joints.
4.3.8 Valves, Improperly positioned or configured valves can result in the
system being unable to collect or deliver heat. If the storage tank is warm, the
problem is in the delivery components. If the tank is cold, the collection components
are at fault.
Most tempering valves fail in such a way that all they deliver is cold water. Since
most are improperly installed (directly above the tank), they eventually fail. -Check
also for correct setting.
Solar loop check valve failure is a common problem. On a cold night after a warm
day, the feed and return temperatures should be equal. If there is a temperature
difference of more than 5F, the check valve is not stopping the loss of heat by
forward or reverse thermosiphoning. (Figure 4-8)
On pool heating systems, the diverting valve may be "pilot operated." The actual
opening and closing of the valve is done by suction or pressure supplied by the pool
pump. Suction is supplied by tubing connected to the inlet piping of the pump.
Pressure is supplied by a tube from the pump's discharge side.
Thermosiphoning in a
4.3 TROUBLESHOOTING OPERATIONS