# US 4,391,268 A · Solar water heater control and protection system

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- Number: US 4,391,268 A
- Document ID: US4391268A
- Status: Granted
- Kind: A
- Application number: 06/238,108
- Filed: 1981-02-24
- Granted: 1983-07-05
- Earliest claimed: 1981-02-24
- Assignees: Solar Dynamics Corporation
- Inventors: Donovan B. Mathes; Floyd B. Hamilton; Douglas C. Spreng
- Web page: https://patentgrep.com/patent/US4391268A

## CPC

- G05D 23/20: with sensing elements having variation of electric or magnetic properties with change of temperature (G05D23/13 takes precedence)
- F24S 40/60: Arrangements for draining the working fluid
- F24S 50/00: Arrangements for controlling solar heat collectors
- G05D 23/1906: {using an analogue comparing device}
- F24S 40/70: Preventing freezing (arrangements for draining the working fluid F24S40/60)
- Y02E 10/40: Solar thermal energy, e.g. solar towers
- Y10T 137/86919: Sequentially closing and opening alternately seating flow controllers
- G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- F24S: SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS (for producing mechanical power from solar energy F03G6/00)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

This disclosure relates to a control and protection system for a solar water heater apparatus, which incorporates a temperature differential controlled variable speed drive for the circulating pump, and a drain down valve which is responsive to low collector temperature, high tank temperature and also to power loss, to serve in combination as a device to optimize efficient energy collection while also protecting the tank against overheating and further protecting the collector panel against freeze-up even during periods of power loss.

## Claims

### Claim 1

A solar water heater system wherein a collector receives a liquid from a tank through a feed conduit and provides said liquid to said tank through a return conduit, and first and second drain down valves connected to said first and second conduits, respectively, are operable to drain said liquid from said system, comprising:
first and second isolating valves respectively situated in said feed and return conduits that isolate said tank from said conduits when said fluid is being drained;
a venting valve connected to said collector and to the atmosphere that allows a flow of air therethrough into said conduits and said collector in response to said system being drained;
a reversible gear motor; and
linkage means for sealing said isolating valves prior to opening said drain down valves and for closing said drain down valves prior to opening said isolating valves.

### Claim 2 (depends on 1)

A valve in accord with claim 1 wherein said linkage means comprising:
a cam having a protruding pin;
said cam having a coupling to the output shaft of said gearmotor;
said isolating valves and said drain down valves each having a rotatable actuating shaft;
a first cam follower coupled to said actuating shaft of a first of said isolating valves and having a slot disposed to receive said pin so that said first cam follower can be reversibly driven by said cam;
a first arm coupled to said actuating shaft of a second of said isolating valves;
a first link coupling said first cam follower and said first arm so that rotation of said first cam follower causes a like rotation of said first arm to thereby actuate both of said isolating valves;
a second cam follower coupled to said actuating shaft of a first of said drain down valves and having a slot disposed to receive said pin so that said second cam follower can be reversibly driven by said cam;
a second arm coupled to said actuating shaft of a second of said drain down valves; and
a second link rotatably coupled to both said second cam follower and to said second arm so that rotation of said second cam follower causes a like rotation of said second arm to thereby actuate both of said drain down valves.