Hot Water Heater Trouble For Your Main Engine Or Am I Over Reacting?

Phil Fill said:

It only takes 1 hour to heat the hot water...... Anyway does not take long to heat the hot water.

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smitty477 said:

"Another AC draw for us will be a CPAP machine for my wife. She just started to use one a couple months ago and it makes a huge difference for her. Currently, we can't use it on our boat without shore power. "


We cruise often with two different folks that use the CPAP machines. They have them configured with stand alone batteries that are good for about 25 hours a piece. They always have two batteries available and never rely on shore power even if we are at docks. Recharge times seem to be about 3 hours per battery so they can do that while underway or with a genset running - this is what they use when camping and one when they went on a cruise.

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sunchaser said:

We are very much off the genset when cruising. But it is a managed part of our longer trips when we're not at a dock somewhere.

There is a general rule of thumb that running a genset above 40 to 50% load is healthy for the generator (armature and windings) end and likewise keeps the constant RPM diesel properly heated. Our 12.5KW unit has a max capacity of 50 amps per leg at 110 V or 50 total at 240 volts.

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Bay Pelican said:

My RemStar Pro CPAP works very well on 12volt. Why run an inverter all night.

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smitty477 said:

"Another AC draw for us will be a CPAP machine for my wife. She just started to use one a couple months ago and it makes a huge difference for her. Currently, we can't use it on our boat without shore power. "


We cruise often with two different folks that use the CPAP machines. They have them configured with stand alone batteries that are good for about 25 hours a piece. They always have two batteries available and never rely on shore power even if we are at docks. Recharge times seem to be about 3 hours per battery so they can do that while underway or with a genset running - this is what they use when camping and one when they went on a cruise.

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stubones99 said:

What model CPAP does she use? Depending on whether she uses a humidifier, she may be able to get a car cig adapter to power the unit off DC and run it more efficiently than through an inverter.

I know that mine splits in half, leaving just the CPAP not the humidifier unit and you hook the air line direct. The CPAP actually runs off 12vdc. so no conversion necessary.

I use a resmed S9 elite unit and here is the adaptor for 12vdc for $100 and can drive both the humidifier and the pump unit off DC battery - includes a pair of alligator clips too.

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Pgitug said:

So keeping the domestic hot water heater plumbed to the main engine is probably OK?

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