UFC 3-440-01
14 June 2002
(c) Storage loop flow rate = 1.25 x AFR.
(d) Propylene glycol concentration required in collector loop.
(e) Minimum pressure drop throughout piping loop, corrected for
propylene glycol solution, if necessary.
(3)
Note the following information about the heat transfer fluid:
(a) Only food-grade propylene glycol/distilled water solutions will be
allowed as the heat transfer fluid.
(b) Percent concentration required (30 percent or 50 percent).
(c) Tamper-resistant seals are required at all fill ports or drains.
(4)
Note the heat exchanger minimum performance requirements:
(a) Solar loop (hot) inlet = 140 degrees F (60 degrees C).
(b) Storage loop (cold) inlet = 100 degrees F (38 degrees C).
(c) Solar loop (hot) outlet = 120 degrees F (49 degrees C), or less.
(d) Solar loop (hot) flow rate = AFR.
(e) Storage loop (cold) flow rate = 1.25 x AFR.
(f) Solar (hot) fluid: 30 percent or 50 percent propylene glycol/water
solution.
(g) Storage (cold) fluid: water.
(5)
Note required pipe diameters.
(6)
Locate expansion tanks near pump inlets.
(7) Require expansion tank bladders to be compatible with propylene
glycol/water solutions.
(8) Require a check valve in the collector loop in order to prevent reverse
thermosiphoning.
(9)
Require isolation valves around collector banks and all major
components.
(10) Require pressure relief shown on all banks.
(11) Require calibrated balancing valves at all bank outlets.
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