69
DRAINING THE CLOSED CIRCUIT FLUID – 52H SERIES
It may be necessary to drain the solar collectors and heat exchanger of a closed circuit system during
maintenance. Draining the solar collectors and heat exchanger of closed circuit fluid should be conducted
within three (3) hours of sunrise when the sun is low in the sky. The closed circuit fluid temperature inside the
solar collectors should be lower as the solar collectors would not have had as much chance to gain as much
heat as later in the day.
Warning: Exercise care to avoid splashing of closed circuit fluid, as fluid discharged from the solar
collectors may be of a very high temperature.
Note: Care must be taken to ensure there is no spillage of the closed circuit fluid onto the roof surface. Any
spilled closed circuit fluid must be cleaned up immediately and the roof surface cleaned of any fluid residue.
The closed circuit fluid discharged from the solar collectors can render the water in a rainwater tank unusable.
Draining the Solar Collectors and Heat Exchanger
1. Cover the solar collectors with an opaque material to prevent absorption of solar energy. If fitted, cover
the OTP valve with a cloth soaked in cold water.
Failure to cover the solar collectors may cause a safety issue.
2. Open a hot water tap and allow the water to run for five minutes immediately prior to draining the solar
storage tank.
This will assist in the transfer of any heat from high temperature closed circuit fluid in the heat exchanger
and solar collectors to the water in the solar storage tank.
3. Close the hot water tap.
4. Attach one end of a hose to the valve drain port of the fill drain valve assembly and place the other end
into a container of sufficient volume to hold the closed circuit fluid.
Refer to the table on page 65 for the volume of closed circuit fluid in the closed circuit of the water heater.
5. Place an absorbent cloth on the roof under the fill drain valve assembly prior to loosening the screw. This
will assist in catching any spilt closed circuit fluid.
6. Loosen (but do not remove) the valve screw on the fill drain valve assembly a few turns to open the valve
drain port.
This will release the pressure in the closed circuit.
7. Very carefully, remove the retaining clip securing the closed circuit relief valve on the right hand side of
the solar storage tank and remove the relief valve.
Warning: Relieved air or closed circuit fluid may be hot.
Closed circuit fluid will drain through the hose.
8. Allow the closed circuit fluid to drain into a container and dispose of in accordance with the relevant local
authority.
Warning: Closed circuit fluid may be hot.
9. If refilling the closed circuit, refer to “To Fill the Closed Circuit” on page 67.
10. When satisfied the closed circuit is drained, tighten the valve screw on the fill drain valve assembly.
◼ Remove the hose from the valve drain port of the fill drain valve assembly.
11. Refit the closed circuit pressure relief valve on the right hand side of the solar storage tank and secure
with the retaining clip.
12. To refill the solar collectors and closed circuit, refer to “To Fill the Closed Circuit” on page 67.
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