Carrier 28QX - Manual (Page 13)

travels to the collectors. From here the loop goes
back to the storage tank thru a 2-1/8 in. pipe. This
down pipe terminates above the highest water level
in the storage tank and must have all horizontal
runs of tubing pitched downward a minimum of
1/4-in ./foot.
A pitch of 3/8-in./ft or l/2-in./ft is acceptable
and provides better drainage than 1/4-in./foot. It is
critically important that this pitch be incorporated
into the horizontal runs. It will assure a properly
draining system and will avoid system failures.
The pipe leaving the storage tank must be at
least 6-in. from the bottom of the tank. The run of
pipe to the pump package must not be less than
2 ft below the lowest water level in the tank. This
condition will assure that the collector pump will
have its required prime at all times. Insulate both
collector supply and collector return piping legs.
Fig. 13 — Solar Collector Panel(s) Piping Loop
on Plain Water System
28QX (Tri-X) Coh Loop (Fig. 14) - This loop
begins with a 7/8-in. pipe leaving the bottom of the
storage tank and entering the pump package at the
7/8-in. stub labelled “storage supply”. The loop
continues thru the Tri-X pump (P-1) and out the
pump package thru the 7/8-in. stub labelled
“28QX supply.” This pipe enters the Tri-X coil at
the “water in” stub. It exits the coil at the “water
out” stub and goes back to the storage tank (top or
bottom entry).
The pipe size and allowable lengths for the
entire loop are listed below. A value of 4 ft should
be used for the length of tubing inside the pump
package.
ALLOWABLE PIPE LENGTHS
Pipe Q.D. (in.)
7/8
1
1
-
1/8
Maximum Equivalent Length (ft)
60
120
240
There is no mounting height restriction on the
Tri-X coil since it is in a closed loop system. There
are, however, other installation restrictions:
a. The termination points of the loop (in storage
tank) must always be below the lowest water
level.
b. The pipe leaving the storage tank must always
be at least 2 ft below the lowest water level.
c. It is recommended that the 28QX coil be the
highest point in the loop. This will make the
bleed valve on the coil an effective air bleed
port. If it is not possible for the coil to be the
highest point, it will be necessary to add a field
installed air bleed valve at the highest point in
the loop.
d. If the 28QX coil is more than 6 ft above the
water level in the storage tank, it will be
necessary to employ a special fill-up procedure.
This will entail adding a booster pump and
pump fitting in the pipe between the pump
package and the 28QX coil. See the Start-Up
Instructions pg 23 for details concerning this
procedure.
RETURN
■■ ■
TERMitiATt BELOW
LOWEST WATER
LEVEL i
Fig. 14 — Tri-X Coil Piping Loop
on Plain Water System
THERMjSrOfi
tNSL'LATtOK
(«TERK»
panels
Fig. 15 — Collector Thermistor Location
13