HTP FP-40SC - Manual (Page 13)

13
Hack Saw High Temperature Joint Compound
Tubing Cutter Tin Snips
Solder Flux Tape Measure
Emory Paper 24” Level
Extension Cord Slip Joint Pliers
Needle Nose Pliers Silicon Caulk and Roof Tar
Pipe Wrenches, 10” and 14” Angle Iron
Open End Wrenches, 9/16 & 7/16 Screw Driver 6” Flat Blade
Screw Driver 6” Philips Wire Stripper or Knife
Wire Cutters Black Latex Outdoor Paint
Adjustable Wrenches 8” & 10” Aluminum Flashing Sheet
D. SYSTEM DESIGN
System design should be completed prior to installation. Solar collectors need to be installed correctly to
ensure high efficiency and, most importantly, safe and reliable operation. Please seek professional advice
for the design and installation of your solar heating system.
NOTE: Only authorized licensed contractors are permitted to install the solar collector.
E. DELTA-T CONTROLLER SETTINGS
Usually a Delta-T ON value of 8 – 20
o
F and Delta-T OFF value of 4 - 10
o
F is appropriate. These settings
may need to be altered slightly according to location and system design. Refer to the instruction manual
provided with the chosen solar controller for appropriate settings.
F. STAGNATION AND OVERHEATING
Stagnation refers to the condition that occurs when the pump stops running. This can be due to pump
failure, power blackout, or as a result of a high tank temperature protection feature built into the controller
which turns the pump off.
If the system is designed to allow stagnation as a means of preventing tank overheating, the collector and
plumbing in close proximity may reach temperatures greater than 395
o
F; components that may be
exposed to these high temperatures, such as valves, plumbing, or insulation, should be suitably rated.
If the system is designed to allow stagnation of the collector when the tank reaches a set maximum level,
steam may form in the collector(s). In such a system, temperature relief valves or auto air vents should be
isolated (using an isolation valve) on the collector outlet, as these options may not be able to withstand
the high temperatures and allow stable stagnation of the collector (may dump hot water).
In the event of component failure or extreme conditions, the PTRV on the hot water storage tank may
open as a safety measure. Under such conditions, the collector will normally reach a maximum
temperature of around 395
o
F. Any heat returning from the collector is generally not enough to cause a
continued increase in tank temperatures (e.g. heat input is less than tank heat losses), and therefore is
able to meet requirements in some regions limiting hot water dumping. A crackling noise may be heard
coming from the supply line when hot water is used as the pressure in the system drops and steam forms.
This is normal.
G. CORRECT SYSTEM SIZING TO AVOID EXCESSIVE OVERHEATING
The system should be sized so that overheating of the tank is difficult to achieve in a single day, even
during hot, sunny periods. If the system is oversized, such that excessive heat is often produced during
summer months, consider installing a drain back system, a heat dissipater unit, and carefully review the
points in Part 3, Section H, Preventing Overheating.