The physics behind water heating is fairly simple to apply and should be able to be managed with tools Minco provides online. There is the issue of cold start warm-up, i.e. what volume of water needs to be raised from temp A to temp B in some duration of time. Heating the entire liter may not be practical, depending on how much time you can allow for warm-up, as it can be very power demanding. It is possible that you would want to isolate some portion of this water and apply demand heating at some flow rate. This becomes more practical. The volume of water and the warmup time in this instance is defined from the numerator in the flow rate and time is the denominator units, i.e. volume per time. The amount of heat energy that must be absorbed in the water is easy to calculate, but it is bit more challenging to put that into action. There would need to be a sufficient heating path for the flow of water to be able to absorb the heat required.
It sounds like you might want an auxilary heater that maintains a minimum temperature in the storage chamber to ensure the water there does not freeze, but if this is an automotive application, you also have to make sure you don't drain the battery of the vehicle if it is not operated for several days.
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