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Houseboat Hot Water System
Designed by Mark Little
 
Hot Water System Power Control Requirements
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To properly design a control system, the requirements of that system need to be known so that the design will actually do what is required, based on the actual operation of the Hot Water System (HWS).

The following modes of pump operation have been observed:

1. Not running.
2. Running continuously.
3. Single short burst of running to charge water line pressure.
4. Repeated small bursts of running due to low flow and the action of the accumulator.
5. Occasional irregular stopping of hot water by operator when filling sink, etc.

The exact durations of these modes have not been accurately measured, so any controller should be able to be altered based on actual experience.

The following list of requirements are the initial thoughts on what is required to properly control the Hot Water System (HWS) Inverter:

1. Turn on Inverter after the pump has been running for at least 1 second.

2. Turn off Inverter after pump has not been running for more than 30 seconds. This is currently an arbitrary guess and may need to be fine-tuned when the controller is operational.

3. Provide method of patching out the inverter control in case of  a failure so that hot water can still be provided using a manual method to enable the inverter in the event of a control failure. In the event of an inverter failure, the main inverter can be used to supply power to the Hot Water System.