warmer than the water in the collector supply line.
The specified SunEarth controller continuously
displays the temperature of the SunEarth collectors
(T1) and the temperature at the bottom of the solar
tank (T2). In addition, you may choose to install
a third temperature sensor (T3); this is normally
installed at the hot water outlet on both single and
double tank systems.
The Cascade Drainback system typically requires a
high head, low flow circulating pump. The maxi-
mum head on the pump curve must be greater than
the static lift head required to fill the system. The
static lift head is the vertical height from the bot-
tom of the drainback tank to the highest point in the
system (usually the collector outlet header). When
the pump is filling the system it will be pumping
against the static lift head and should provide no
less than half the design flow of the collector. Once
the system has been filled to the top of the collector,
water will start to cascade down the return line fill-
ing the return line as far as the drainback reservoir.
Once this pipe is fully flooded the return line will
start to siphon, resulting in an increase in flow as
the system transitions from the filling condition to
the running condition. In the running condition the
flow rate should not exceed 4 ft/s. Good pump selec-
tion requires that the pump provide enough lift for
the filling condition without excessive flow in the
running condition. This is usually achieved using
a pump with a “steep” pump curve. For multistory
buildings, this can be especially challenging unless
the drainback tank is located on the upper floor.
When there is a risk of pipe errosion due to high
flow rates, a pump throttling valve (COMPONENT
#22) may be located on the discharge, or upstream,
side of the pump to adjust the solar loop flow rate
and to prevent errosion of solar loop. A throttling
valve on the return piping from the collector to the
drainback tank can also be beneficial in situations
where excessive noise is experienced due to high
flow rates into the drainback reservoir.
A brass boiler drain (COMPONENT #11) must be
installed at the lowest point in the system to allow
for charging the solar loop piping and to serve as a
drain valve for manual draining and maintenance.
P.13
DB-5.0
DB-7.5
DB-10.0
SunEarth
M
odel No
.
12
18
24
W
idth
Inches
5
5
5
Depth Inches
50
50
50
Length Inches
42
56
84
5.0
7.5
10.0
82
117
164
220
220
220
3/4
3/4
3/4
Dry
W
eight
(lbs)
Fluid Capacity
(US gal
)
M
ax
Pr
essur
e
(psig)
ConnectionPipe Dia. (in)
W
et
W
eight
(lbs)
Table 3 - Specification For SunEarth CopperStor Drainback Tank
Max. Temp of 210° F
Array
DB 5.0
DB 7.5
DB 10.0
1 EP/EC-40
82
138
194
2 EP/EC-21
76
132
188
2 EP/EC-32
73
129
185
2 EP/EC-32
62
118
174
Pipe run lengths for 1/2” supply and 3/4”
return lines.
Table 1
Array
DB 5.0
DB 7.5
DB 10.0
1 EP/EC-40
61
103
144
2 EP/EC-21
57
98
140
2 EP/EC-32
54
96
138
2 EP/EC-32
46
88
130
Table 2
Pipe run lengths for 3/4” supply and return
lines.