ENHANCING HEAT TRANSFER (A)
18-22" Flex Duct
(15-100 ft in length)
Cloth Support
Straps to Peak
A simple method of enhancing heat transfer within the attic is to suspend from the attic’s
peak a length of large flexible duct. Place the flexible duct adjacent to the PCS1’s heat transfer coil
1-2 inches from the fins. This allows “distant” air to be more easily drawn across the heat transfer
coil. Centering the flex duct on the coil’s surface also allows “local” air flow to be drawn across
the coil at the same time.
This method is useful in attics where the PCS1 would have an obstructed air flow path. It
promotes a larger circular airflow pattern thereby enhancing attic heat transfer. It is also useful in
attics with cathedral like ceilings that use scissor joists. These ceilings have a two-(2) foot attic air
space above the cathedral like ceiling.
Large flex duct is available at building supply centers. Standard cloth support straps are
available for suspending the large flexible duct from the attic’s peak. Both the large flex duct and
support strap are relatively inexpensive.
1. Thermistor temperature sensors are supplied with the LX220. These [10K] sensors are
nonpolarized and are denoted by the same color of leads [black]. This means the leads can be
hooked up either way to the WTR or SOL terminals.
2. Use 22-gauge wire for connecting the attic thermistor to the LX220.
3. The attic temperature sensor is connected in series with the white internal float leads
located on the right side of the PCS1 by the electrical clamp. The internal float is a normally closed
switch, which opens if the water in the base pan rises to 3/8”. This could only occur under a leak
of the coil or a malfunction of the motor and fan. Do not attempt to use this float for any other use.
Contact ratings are only 15 ma and its intended use is strictly with the attic temperature sensor.
NOTE: If you raise this float by hand, the switch will open when the float is off the base
pan by approximately 1/8”. In actual water, 3/8” is required to raise the float to an open circuit.
The float will not reset until lowered all the way.
4. When the internal float rises and opens the circuit to the attic temperature sensor, the
LX220 interprets this as an extremely cold attic condition. It therefore turns off the bypass valve
CAUTION: This internal protection for the PCS1 is only available during the time the
LX220 is operating in “automatic”. If the controller is placed into ON[manual override], it
will ignore the attic temperature sensor and float.
5. A second [optional] relay can be installed in the LX220 to automate a pool vacuum
pump [i.e. Polaris, etc.]. This relay plugs into the SWPsocket on the LX220.
6. On poor solar days, the pool's pump may not achieve a minimum amount of desired
filtration time. If a certain minimum filtration time is desired, a pump timer should be installed as
shown to bypass the LX220 during optimum solar time. The pump timer should be set to start at
12 noon and run for the length of minimum time desired.
Wired this way, the pump timer will not affect the operation of the PCS1 heat exchange
system by being miss synchronized in a solar context.
7. The LX220 relays provide two sets of contacts rated at 2 hp maximum. If additional
contacts are desired, substitute a different 24-vdc relay that has the correct amount of contacts
desired. OR, connect additional relay(s) in tandem [next item].
8. Additional 115 vac or 230 vac relays can be connected in tandemfrom the current
power relay contacts to achieve amplification of the power handlingcapabilities of the
LX220. Follow national and local electrical codes when modifying relay output circuits to achieve
additional power handling capabilities.
9. Some timers provide for a manual override function eliminating the need for an
additional electrical switch and/or circuit if a timer is used. Also, a timer set to operate both the
pump and the PCS1 from 11 a.m. to 7 p.m. can achieve a SEMI-AUTOMATIC operation of the
system without using the LX220. However, remember that the PCS1 can cool down a pool if the
attic is cooler than the pool!
10. The Flowreversal™ valve can be automated. This requires an optional module and a
second valve operator. The part numbers are MOD-VLV and FR-VOR respectively.
Theoretically, an automated flowreversal valve would yield optimum cleaning andheating.
However, experience questions this. SolarAttic, Inc. does not recommend the automation of the
11. The diagram that follows shows a suggested method and is not a substitute for national
and local codes. Where codes apply, they supersede the attached wiring diagram. All wiring
should be done by a qualified electrician and must comply with electrical codes.
12. Note that 220-vac power is typically available at the pool’s pump already [in most
cases]. This power can be tapped for the LX220 to use.
13. We recommend that the pool’s pump be slaved to the LX220. This will cause the
pump to operate only during the solar collection process, which is typically 10 hours per day. If
the pump is sized properly, this should provide adequate filtration. On poor solar days, a timer can
augment this by providing a minimum amount of pump run time for filtration as previously
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