System information

24
Geothermal Applications
Carrier: Turn to the Experts.
Headers that utilize large diameter pipe feeding the last circuits
should not be used. PE 1-1/4” IPS pipe requires 9.5 gpm [36 l/m]
to attain 2 fps [0.6 m/s] and since increasing the fl ow through the
last circuit would also require increasing the fl ow through the other
circuits at an equal rate as well, we can estimate the fl ush fl ow
requirements by multiplying the number of circuits by 9.5 gpm [36
l/m] for 1-1/4” IPS. For instance, a 5 circuit loop would require 5
circuits x 9.5 gpm/circuit = 47.5 gpm [5 circuits x 36 l/m per circuit
= 180 l/m or 3.0 l/s] to attain fl ush fl ow rate. This is clearly a diffi cult
fl ow to achieve with a pump of any size.
Figure 5: Typical “Laydown” Header
Header Layout - Generally header layouts are more cost effective
with short headers. This requires centrally locating the header to
all circuits and then bringing the circuits to the header. One of the
easiest implementations is to angle all trenches into a common pit
similar to a starburst. This layout can utilize the laydown or ‘L’ header
and achieves reverse return fl ow by simply laying the headers down
in a mirror image and thus no extra piping or labor. Figure 5 details a
“laydown” header.
Figure 4b: Typical Header Through 5 Tons
Closed Loop Design/Installation Guidelines