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How do I convert an Active Open Loop Sunspool Draindown solar heater system to Active Open Loop with Freeze valve?
Sun-Spool is a brand name for a valve that was used in Active Open Loop solar heaters to automatically drain the water in the collector loop to protect it from freezing. It is typically used in southern climates, but may have been used in northern climates.
The Sunspool has been discontinued for over 15 years. The only parts still available are an o-ring kit and check valve kit; these would be required if it is leaking, or if it is thermosyphoning at night (heated water is going up return line and cooling off tank). These kits are available for a limited time; ask for price quote and availability. If it is not functioning, then the valve can not be repaired. The only solution is to convert to Active Open Loop w/Freeze valve (Note that this configuration is only good when the outside temperature occasionally drops below freezing; if it is consistently below freezing, then the system must be manually drained.
To convert an Active Open Loop Sunspool Draindown solar heater system to Active Open Loop w/Freeze valve, these are the parts required:
• Solar Spring Check Valve or preferably
•
Erie Motorized Check Valve
•
FP45 Freeze Protection Valve
Freeze Protection Valve Application Considerations
Other parts that may be required to replace Sunspool valve to allow for panel loop isolation and manual draining would be (2) - ½ Ball Valves and (2) - ½ Boiler Drains. These items can not be purchased online at this time; ask for price quote.
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VView
Owner's Manual
for Active Open Loop systems w/Freeze valve to show operation and basic component locations.
Below is a standard diagram of an Active Open Loop Systems.
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Freeze Protection Valve Application Considerations
11. The
Invensys FP45 Freeze Protection Valve functions properly provided the valve is installed in a location, where during operation, the warmer supply water first passes through the collectors and/or pipe to be protected and then through the valve. The "Freeze Protection Valve(s)" should be located in a position to allow good water distribution through the solar panel so that when the valve opens, water flows as evenly as possible through all the collector tubes. Location of the valve may vary depending on the system design and piping.
2. Select a mounting position where the valve will sense the coldest anticipated ambient temperature. When used in conjunction with active systems, the valve should also be located within close proximity of the collector outlet with 2"-6" offset below the collector header (see illustration). Do not mount in a position where the valve will be exposed to an unnatural heat source (i.e. poorly insulated roof, dryer or furnace vents, etc.).
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3. The system must be subjected to normal operating pressures of between 20 and 125 PSI at all times for the valve to operate properly. Do not shut off water supply to the collectors or isolate the collectors from the city water supply.
4. When the valves are required, be sure they are operating and installed in a proper location with respect to the “Freeze Protection Valve(s).” Water flow must be prevented from “bypassing” the collector. If the check valves leak, water flow may be bypassed through the check valve rather than through the collector.
5. Do not insulate the "Freeze Protection Valve(s)" or exposed pipe between the collector and the "Freeze Protection Valve(s)." Sections of exposed pipe where no water flow exists during valve operation should be heavily insulated. The valve(s) should be mounted close to the collector to minimize the length of exposed pipe.
6. Install by applying torque with a wrench to the square metal inlet flange. Do not apply torque to the plastic body.
7. For proper utilization of the anti-siphon port, the "Freeze Protection Valve(s)" should be installed in a vertical position with discharge port down.
8. To enhance customer satisfaction of this product, we recommend a plastic discharge tube be connected to the 1/4" pipe threads or the 5/8" barbs, then routed to a safe, nonobjectionable location where the discharged water will drain.
9. If a discharge tube is used, make sure it will drain freely and is installed in accordance to local codes. Avoid water traps in the discharge tube that could freeze and prevent drainage. The valve has an alternate path for discharge water flow should the discharge tube become impaired.
10. Do not attempt to disassemble the top cover. The inlet retention flange can be removed to inspect the screen for periodic cleaning and replacement.
WARNING: Solar collectors can reach internal temperatures up to 10 degrees below the outside ambient air temperature.
SStandard Active Open Loop Solar Systems
typically require a model
FP45 valve to ensure proper protection.
Passive Batch or Integrated Collector
Storage (ICS) systems such as the ProgressivTube
have a much larger volume and mass of stored
water, and will not freeze as quickly as a Active
Open Loop Solar System, therefore they can
typically utilize a model
FP35 valve.
This condition results from a phenomenon known as “night-sky emissivity”. The emissivity of a material is the ratio of energy radiated by the material (solar panel) to energy radiated (or absorbed) by a black body (the sky); it is a measure of a material's ability to absorb and radiate energy. Since solar collectors are coated with a black surface they are very good at conducting and emitting energy. When the outside temperature approaches freezing, the surface of the solar collector begins to emit energy to the night sky.
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When the atmosphere is clear with no clouds, the transfer of energy is accelerated. In layman terms, this means that on a cold clear night, the water in the solar panel can be up to 10 degrees colder than the outside temperature.
A Freeze Protection Valve needs to begin opening when the outside temperature drops to 42 degrees and below. As the temperature drops from 42 to 32 the volume of water discharged from the valve increases.
Consult the owner’s manual of your collector and/or system to determine the correct valve model to use; Solar Direct and/or The Energy Supermarket makes no claim as to the correct valve to use, and/or its usage and application; and assumes no liability for damages resulting from correct or incorrect use of this product.
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