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depletion rate, and cause the formation of scale and
other deposits on the heat exchanger's internal heat
transfer surfaces.
Distilled or deionized water is required.
The HTF pH level must be maintained between 8 and
10 to minimize corrosion and glycol oxidation in the
piping system.
5) SYSTEM START-UP PROCEDURES
Throughout the installation procedures outlined
in Section 4 above, emphasis has been placed on
the correct procedures for plumbing and wiring
the components, checking for plumbing leaks,
pressurizing the collector glycol loop, and eliminating
any trapped air that can impact fluid quality and pump
performance. Having completed these tasks it is time
to start up your Rheem solar water heating system.
When the glycol loop has been fully charged and
the pressure is around 25 psi (check the pressure
gauge, No. 7), set the differential controller to
the "Automatic" setting. This will activate your
circulating pump. The controller allows you to set the
"on" differential. Turn the red rotary switch inside the
control housing to 12.
Adjust the valve settings in accordance with Section 6
below.
Table 4
Percent (volume) Glycol Concentration Required
Temperature F
For Freeze Protection
20
18%
10
29
0
36
-10
42
-20
46
-30
50
-40
54
-50
57
-60
60
26
collector glycol loop. An inexpensive flow meter
such as manufactured by Blue White Industries or
Letro is recommended as an optional system
component. A flow meter allows you to monitor
6) THREE MODES OF SYSTEM OPERATION
Both single and double tank Rheem systems are
Percent (volume) Glycol Concentration Required
designed to accommodate three separate modes of
operation. Your solar water heating system can, (1)
Temperature F
provide 100% solar operation during good weather, or
(2) serve as a preheater to your electric water heater
adding solar energy when and as available, or (3)
completely bypass the solar collector loop and solar
storage tank and run 100% on utility power during
inclement weather.
Single Tank Operating Instructions:
6.1 100% Solar Operation:
Turn off the circuit breaker to your solar storage
tank. If a water heater time switch has been installed,
collector glycol loop. An inexpensive flow meter
set the switch to the "off" position. If you have a
such as manufactured by Blue White Industries or
mechanical timer remove the trippers from the face of
Letro is recommended as an optional system
the switch.
component. A flow meter allows you to monitor
6.2 Solar Preheat
and adjust the flow rate through the piping and
also to visually inspect the HTF fluid quality.
Leave the circuit breaker to your solar storage
tank on and set the tank thermostat to the lowest
Set the controller to the "off" position and pro-
acceptable temperature setting. The electric resistance
ceed to the next step.
heating elements will come on only when the tank
4.12.4 Mix the Dowfrost HD propylene glycol
temperature falls below the thermostatic set point.
and distilled water mixture in accordance with
If the solar heated water entering the tank is warmer
Table 4 and Table 5 in a large clean bucket. You
than the thermostatic set point, the electric heating
will need a second empty bucket as well. The
elements will not come on. If you have a water heater
charging process also will require a low flow
timer, you may preset the timer to turn the heating
diaphragm pump (Flojet or equal) to fill and pres-
element on and off at specified times throughout the
surize the collector loop.
day if desired.
Open the upper charge faucet and allow the
Connect the discharge side of the pressure pump
pressure from the expansion tank to push the
6.3 100% Utility Power
to the upper charge faucet (No. 9) Place the
water in the glycol loop back to prime the pres-
pump suction side hose in the glycol solution.
sure pump. When the hose in the bucket con-
Leave the circuit breaker to your solar storage tank on
For Burst Protection
Close the isolation ball valve (No. 10) and con-
taining the glycol mixture stops bubbling you
and close the isolation ball valves in the collector loop
12%
nect a second hose to the lower charge faucet
may begin charging the collector loop with glycol.
(Nos. 5 and 10). In this mode of operation you must
20
(No. 11). Place the other end of the hose in the
turn off the circulation pump. To turn the pump off
With both charge faucets now open, run the
empty bucket.
24
Flojet pressure pump until the pinkish glycol mix-
28
ture begins flowing into the empty bucket.
Quickly switch the hose from the empty/return
30
Total Collector Loop Fluid Capacity In Gallons*
bucket to the bucket containing the glycol mix-
33
ture. Continue to circulate the fluid using the
35
pressure pump until the bubbling has stopped
35
and the air has been purged.
35
4.12.5 After charging the collector loop, shut
the lower charge faucet and let the pressure
* Assumes a total 100' pipe run using 3/4" Type
pump drive up the loop pressure to the appropri-
M hard copper tubing. The Rheem/Ruud heat
ate level (Generally in the range of 25 PSI). To
exchanger has a 2.2 gallon fluid capacity.
more accurately calculate the proper pressure
Table 4
For Freeze Protection
20
18%
10
29
0
36
-10
42
-20
46
-30
50
-40
54
-50
57
-60
60
Table 5
1 Collector System
2 Collector System
For Burst Protection
12%
20
24
28
30
33
35
35
35
4 Gallon
5 Gallons
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