METHOD AND SYSTEM FOR POSITIVE EVACUATION OF SOLAR COLLECTOR

Abstract

A method and system for positive evacuation of water from a solar collector using a bypass line which diverts a portion of water from the feed line of the solar collector to an inlet of a water pump. When the solar water heating circuit is turned off, suction created by the filtration pump rapidly evacuates all or substantially all water present in the solar collector. The system should include a water level switch on the feed line to the solar collector, a drain valve that allows pool water to evacuate from the solar collector and associated piping when water is present, a control mechanism that relays information from the water level switch to the drain valve, a small drain line that connects the solar pool heater feed and return lines to a water pump inlet, and a check valve to prevent by-pass.

Description

This invention relates to a method and system for positive evacuation of water from a solar collector. More particularly, the invention relates to a method to ensure positive water removal from the solar collector using a bypass line which diverts a portion of water from the feed line of the solar collector to an inlet of a water pump.

BACKGROUND OF THE INVENTION

Solar pool heating collectors are gaining wide acceptance in both residential and commercial applications due to their ability to heat pool water to a comfortable temperature and their low installation and operational costs. These solar heating collectors typically comprise an intake and exhaust manifold connected to one or more solar collector panels which transfer solar energy to water contained in conduits in the panels. U.S. Pat. Nos. 6,787,116 and 7,112,297, the disclosures of which are each incorporated by reference herein in their entirety, disclose an improved solar collector.

Solar pool heating systems incorporated into a commercial swimming pool must accommodate continuous pumping. More particularly, public health codes require filtration pumps of commercial pools to operate continuously so as to filter the pool's water volume a minimum of 4 times in a 24 hour period. Of course, residential pool pumps may also be operated continuously.

The continuous filtration/flow requirement of commercial pools is at odds with a solar heating apparatus, whose collector cannot absorb solar radiation at night. Instead, the solar collector can act as a radiator at night, and reduce the temperature of water flowing through it. Moreover, freezing temperatures can damage the solar collector and its associated plumbing.

When a solar pool heater is operating, water flow from the filtration pump is diverted to the solar heating collectors by the use of a three-way valve, a three way valve with a booster pump or a two-way valve and booster pump. The solar heating operation continues until either the swimming pool water reaches the desired temperature or usable solar energy required for heating the pool is no longer available.

Solar heating is typically terminated by closing the water flow path to the solar collectors and turning off the solar booster pump, if present. However, terminating the solar heating operation can trap and immobilize pool water in the solar collectors and in associated feed and return piping. Unless this stationary pool water is removed, the solar heating collectors and associated piping can be damaged by freezing temperatures. Also, stationary water in the solar heating collector can rise to temperatures up to or exceeding 160° F. (71° C.), which can cause scalding when the swimming pool heater cycles on again, and the water is permitted to return directly into the swimming pool.

Yet another reason to remove water from the solar collector when it is not in use is to reduce stress on the collector's mounting structures and hardware. The weight per square foot of a solar collector is doubled when it is full of water. Evacuating water from the solar collector can thus increase the service life of the collector, its mounting structures and hardware.

One solution to the problem of stagnant pool water is to simply drain the solar collectors and associated piping to waste each time the solar pool heater is turned off. This solution is unsatisfactory because new make-up water would continually be required, which is expensive, wasteful and would require additional heating. U.S. Pat. No. 4,044,754 discloses an automated freeze protection system in which a temperatures sensor automatically actuates appropriate valve means to rapidly drain water from a solar collector when temperature within the collector approaches 32° F. (0° C.). U.S. Pat. No. 4,280,478 discloses a freeze protection apparatus for solar collectors in which the working fluid contained in the solar collector is permitted to drain from both the input and output tubes of the collector when a first predetermined temperature of the working fluid is detected. The collector filled through both the input and output tubes when a second predetermined temperature is detected.

Another solution would be to drain the solar collector into the fill line, or surge tank if available, each time the solar pool heater is turned off. U.S. Pat. No. 4,237,862 discloses a closed, pressurized solar heating system utilizing a valveless gravity drain into a sump tank.

A third option, if the pool heating apparatus is located sufficiently close to the pool, is to run a gravity drain line across the pool decking to the surface of the pool. However, the gravity drain line would present a safety hazard.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention relates to a method for positive evacuation of water from a solar collector, comprising

• • i) pumping water from a swimming pool through a feed line to a solar collector and back through a return line to said swimming pool during operation of said solar collector;
  • ii) diverting a portion of pumped water from said feed line so that it bypasses said solar collector and is returned to an inlet of a water pump during operation of said solar collector, thereby creating a bypass flow from said feed line to said water pump;
  • iii) terminating operation of said solar collector by closing a water inlet to said feed line; and
  • iv) positively evacuating water from said solar collector using suction created by said water pump and said bypass flow until substantially all water has been removed from said solar collector.

In another aspect, the present invention relates to a system for positive evacuation of a solar pool heating apparatus, comprising

• • a) a water feed line having an inlet and an outlet, and adapted to convey water from a swimming pool to a solar heating apparatus,
  • b) an inlet valve to open and close said inlet of said water feed line,
  • c) solar heater control means for opening and closing said inlet valve in response to data received from at least one of a water temperature sensor and a solar energy sensor,
  • d) a return line having an inlet and an outlet, and adapted to convey water from said solar heating apparatus back to said swimming pool,
  • e) a solar heating apparatus comprising an intake manifold operatively connected to said outlet of said water feed line and a solar collector panel, and an exhaust manifold operatively connected to said inlet of said return line and said solar panel,
  • f) a bypass line connecting said water feed line and said return line, said bypass line adapted to convey water from said water feed line and said return line to an inlet of a filtration pump of said swimming pool,
  • g) a bypass valve located in said bypass line,
  • h) a water level sensor to indicate whether water is present in said water feed line, said water level sensor being located downstream of said bypass line,
  • i) bypass valve control means to close and open said bypass valve in response to data received from said water level sensor,

such that a portion of water flowing towards said solar heater apparatus is permitted to flow through said bypass line when said water level sensor indicates water is present in said water feed line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of one embodiment of a system which can be used to positively evacuate a swimming pool solar heating apparatus according to the invention.

FIG. 2 is a circuit diagram of relay switch for controlling operation of a three way valve to govern the diversion of water into a solar heating collector from a pool water filtration system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:

The inventor has discovered stagnant water may be positively evacuated from a solar collector and its associated piping through the use of a bypass line which creates a suction effect in combination with the pump of the pool filtration system. When the solar water heating circuit is turned off, suction created by the filtration pump rapidly evacuates all or substantially all water present in the solar collector. Thus, “positive evacuation of a solar collector” means gravity drainage aided by the filtration pump's suction.

In order to achieve positive evacuation of water from the solar collector, the system should include a water level switch on the feed line to the solar collector, a drain valve that allows the pool water to evacuate from the solar collector and associated piping when water is present, a control mechanism that relays information from the water level switch to the drain valve, a small drain line that connects the solar pool heater feed and return lines to pump inlet, and a check valve to prevent by-pass.

The invention will be further described by reference to a preferred embodiment illustrated in the attached drawings.

FIG. 1 illustrates the operation of the inventive method as applied to a commercial swimming pool equipped with a solar heating apparatus incorporated into a conventional continuous filtration system. When the solar heater is not being used, water from swimming pool 10 is piped to a pump 20 which forces the water through filter 30, water temperature sensor 35, check valve 40 and three-way valve 50 before being returned to swimming pool 10 via return line 55.

Pump 20 is operated continuously, and thus water is continuously filtered, in accordance with public health codes. Accordingly, water returning from return line 90 cannot gravity drain through the outlet tee 100 due to the pressure in the main filtration line generated by pump 20.

Three-way valve 50 is preferably a motorized ball valve. Electronic temperature control 60 opens and closes three-way valve 50 in response to data received from water temperature sensor 35 and solar sensor 65. During solar heating operation, three-way valve 50 is open and a portion of the filtered water is piped through water feed line 70 past T-joint 71 and water level sensor 4 to solar collector 80.

As illustrated in FIG. 1, the water is typically piped into a lower intake manifold of solar collector 80, and then rises through a plurality of small conduits before being collected in an upper exhaust manifold. Thermal energy absorbed by the solar collector from sunlight is transferred to the water as it rises in the collector's conduits. Water thus heated in solar collector 80 is piped through return line 90 past T-joint 82, isolation ball valve 98, check valve 95 and T-joint 100 into return line 55, which delivers the heated water to pool 10.

A positive evacuation flow is created by installing a bypass line 72 between water feed line 70 and return line 90, and draining bypass line 72 to a return line 76 which feeds this water to pump 20. During operation of the solar heater, relay control switch 3 maintains drain valve 78 in the open position while water level sensor 4 indicates water is present. A small amount of water is thus permitted to flow from water feed line 70 through T-joint 71 into bypass line 72 and through T-joint 74 into return line 76, and then past drain valve 78 and back to pump 20. Alternatively, T-joint 74 and drain valve 78 may be combined into one three-way valve that performs the functions of both components.

In similar fashion, a small amount of heated water returning to the pool through return line 90 is permitted to pass through T-joint 82 into bypass line 72. This heated water then flows past check valve 84 to T-joint 74 and into return line 76, which may be operatively connected to the pump inlet line, for example by a T-joint or a saddle fitting. The water in return line 76 is thus drawn by pump 20, thereby creating a positive evacuation flow.

Electronic temperature control 60 closes three-way valve 50 either when water temperature sensor 35 indicates the pool water is at or above the desired temperature or when solar sensor 65 indicates usable solar energy required for heating the pool is no longer available. Closing three-way valve 50 closes the flow path to solar collector 80 and may also turn off a solar booster pump, if it is present as part of the system. Pump 20 continues to draw water from return line 76. Accordingly, pool water present in water feed line 70, solar collector 80 and return line 90 is positively evacuated through open drain valve 78 by pump 20.

A vacuum relief valve 00 may be employed to allow air to enter solar collector 80, water feed line 70 and return line 90 to aid in water evacuation. Vacuum relief valve 00 may be placed in the outlet header of solar collector 80 opposite the end that return line 90 exits solar collector 80. Alternatively, vacuum relief valve 00 can be placed in water feed line 70 above water level sensor 4 or in return line 90 above T-joint 82.

Relay control switch 3 closes drain valve 78 when water level sensor 4 indicates water is no longer present, i.e., that the water has been evacuated to the level of water level sensor 4. Closing drain valve 78 prevents air from being introduced to pump 20, which could cause cavitation, loss of prime and pump function.

Water level sensor 4 is preferably located within the building, and thus within a heated air space. Locating water level sensor 4 in this heated air space will ensure the portions of water feed line 70 and return line 90 which extend outside the building and which are thus exposed to the elements are completely evacuated before drain valve 78 is closed.

Once solar collector 80 and the exposed portions of water feed line 70 and return line 90 have been evacuated, there is no danger of stagnant pool water freezing or scalding water being released into the pool. Moreover, the weight of the collector and its associated piping has been significantly reduced, thereby extending the service life of these components.

The solar pool heater will cycle on when water temperature sensor 35 indicates the pool water temperature has fallen below the desired temperature and solar sensor 65 indicates usable solar energy required for heating the pool is available. Electronic temperature control 60 will then open three way valve 50, thereby permitting water to flow through water feed line 70 towards solar collector 80. Relay box 3 opens drain valve 78 once water level sensor 4 reports the presence of water, thereby allowing a small amount of pool water to once again bypass the solar collector 80 to create a positive evacuation flow.

It should be noted that when three way valve 50 diverts water towards solar collector 80 air present in the system will be purged by the force of water flow through return line 50 into pool 10.

The various valves, pumps, piping and filter comprising the system of the present invention are conventional and well known to those of ordinary skill in the art. Thus, for example, drain valve 78 is preferably a motorized ball valve, commercially available from Hayward Industrial Products Inc., Elizabeth, N.J., under Hayward Series EA Automated Ball Valve, Model No. EATB1075STE. However, a solenoid valve may also be used in place of a motorized ball valve for drain valve 78.

FIG. 2 illustrates one embodiment of a wiring diagram to control operation of drain valve 78. As illustrated therein, water level sensor 4 may be a conventional float valve, powered with conventional 120 volt power, with its “up” position designated as the open position. A suitable single stage liquid level switch is commercially available from Oil-Rite Corporation, Manitowoc, Wis., under model No. B-2364-1.

Output from water level sensor 4 is operatively connected to relay control switch 3, which is also powered using conventional 120 volt power. A suitable single stage relay control switch is commercially available from Oil-Rite Corporation, under model No. A-4621-1. Output from the relay control switch is operatively connected to drain valve 78.

The above-described method and system provide a fail-safe drainage control should filtration pump 20 ever lose power while the solar collector is operating and filled with water. Should pump 20 fail, water present in water feed line 70, solar collector 80, return line 90, bypass line 72 and return line 76 will drain by gravity to pool 10 via the inlet line through pump 20 and return line 55.

Those of ordinary skill in the art will recognize many variations of the above system may be made without departing from the scope and spirit of the basic invention. For example, a conventional gas-fired heater may be incorporated into the system using a conventional by-pass valve. Similarly, the system may be fitted with at least one pressure relief valve and/or at least one vacuum relief valve. While the invention has been illustrated by reference to a commercial swimming pool (which requires continuous filtration), the invention is equally applicable to a residential pool.

Claims

1. A method for positive evacuation of water from a solar collector, comprising

i) pumping water from a swimming pool through a feed line to a solar collector and back through a return line to said swimming pool during operation of said solar collector;

ii) diverting a portion of pumped water from said feed line so that it bypasses said solar collector and is returned to an inlet of a water pump during operation of said solar collector, thereby creating a bypass flow from said feed line to said water pump;

iii) terminating operation of said solar collector by closing a water inlet to said feed liner; and

iv) positively evacuating water from said solar collector using suction created by said water pump and said bypass flow until substantially all water has been removed from said solar collector.

2. The method of claim 1, wherein a water level sensor located in said feed line is used to determine when substantially all water has been removed from said solar collector.

3. The method of claim 1, further comprising diverting a portion of water exiting from said solar collector via said return line to said swimming pool is diverted from said return line and added to said bypass flow.

4. A system for positive evacuation of a solar pool heating apparatus, comprising

a) a water feed line having an inlet and an outlet, and adapted to convey water from a swimming pool to a solar heating apparatus,

b) an inlet valve to open and close said inlet of said water feed line,

c) solar heater control means for opening and closing said inlet valve in response to data received from at least one of a water temperature sensor and a solar energy sensor,

d) a return line having an inlet and an outlet, and adapted to convey water from said solar heating apparatus back to said swimming pool,

e) a solar heating apparatus comprising an intake manifold operatively connected to said outlet of said water feed line and a solar collector panel, and an exhaust manifold operatively connected to said inlet of said return line and said solar panel,

f) a bypass line connecting said water feed line and said return line, said bypass line adapted to convey water from said water feed line and said return line to an inlet of a filtration pump of said swimming pool,

g) a bypass valve located in said bypass line,

h) a water level sensor to indicate whether water is present in said water feed line, said water level sensor being located downstream of said bypass line,

i) bypass valve control means to close and open said bypass valve in response to data received from said water level sensor,

such that a portion of water flowing towards said solar heater apparatus is permitted to flow through said bypass line when said water level sensor indicates water is present in said water feed line.

5. The system of claim 4, wherein said filtration pump is capable of filtering a minimum amount of water equal to four times a volume of said swimming pool within a 24 hour period.

6. The system of claim 4, wherein said inlet valve of said water feed line comprises a three-way motorized ball valve.

7. The system of claim 4, wherein said inlet valve of said water feed line comprises a two-way valve in combination with a booster pump.

8. The system of claim 4, further comprising a gas-fired pool heater.

9. The system of claim 4, further comprising at least one pressure release valve.

10. The system of claim 4, further comprising at least one vacuum relief valve.