"Roger Long" wrote in news:xkWRf.18096$jf2.9960
@twister.nyroc.rr.com:

The AC element on my hot water heater is 1250 watts.

Can you safely draw from an inverter while the engine is running? If
I put in a 1500 watt inverter and used it carefully to only run the
water heater (which would also be getting waste heat from the cooling
water coil) and was sure that my other 12 V loads were minimal at the
time, could I get my hot water tank heated up in the 5 - 10 minutes
that I do with shore power? (It takes motoring half a day to do it
with the waste heat alone from my 20 hp diesel).

Or, will this burn up my little 35 amp alternator? I have a 55 I can
put in but it needs a different voltage regulator.

I would never try to make hot water from the batteries through the
inverter for obvious reasons.

--

Roger Long


Ok, let's do the arithmetic.

Power = Volts X Amps
So, screwing that around, at 1,250 watts at 14V (charging full), let's
see, carry the 2, push this button, turn the calculator right side up and
we get....Wow! damned close to 90 Amps! The inverter, not a perfect
device but fair, would probably draw 95A at 14VDC to run the water
heater. Hmm...The alternator will put out 35A so we won't ever see
"charging" if this inverter is on....nope. We'll see DISCHARGING! So,
our voltage is a smidgen high in the calculation if we
discharging....Let's say 12.2V if the batteries are up, at least for a
while. 1,250 watts at 12.2V, carry the 2, push this button, rotate the
calculator around so we can see the display and it reads......WOW! 102
AMPS NOW round that up to 110 from the inverter! 35A coming from the
tiny alternator running wide open (it won't destroy it, by the way, it
puts out what it can)...and the ol' house batteries are gonna need to
supply 110A minus 35A = SEVENTY FIVE AMPS! How big did you say those
house batteries were?!! Ouch! PHooey....This isn't gonna work, is it?

You'd be makin' hot water from the house batteries, even WITH the engine
running full throttle....(sigh).

(Calculator to off)....

I saw on a previous post about cooling water heating so slow......

Question: I assume this Atomic 4 is direct seawater cooled, right, as
you say the cooling seawater is heating the hot water tank on its way to
the exhaust....right? Doesn't these seawater systems cooling the engine
have to run lots of water through them to cool the exhaust so it doesn't
burn the exhaust hoses? I can see that water never gets "hot", like a
car running without a thermostat. I've never been around an Atomic 4 so
don't know what the cooling system loop looks like, so I'm asking.

If it DOES have a restrictive thermostat, no water heating in the hot
water tank would happen until that thermostat opened. Wouldn't a
seawater cooled engine have to have a seawater bypass into the exhaust
around this thermostat-controlled engine to force lots of water into the
exhaust before the exhaust hoses melt before the thermostat opens? If
that's the way it works, isn't your plumbing forcing COLD seawater,
bypassed around the engine, through the hot water tank...before the
engine thermostat makes it warm....on its way into the exhaust??

Coolant looped systems with a seawater heat exchanger, I can see, would
heat water much better as the coolant is really hot, like your car, with
its thermostat actually pressurizing the water through the hot water
tank's exchanger. Lionheart's Perkins 4-108 heated water at sea produces
a LOT faster recovery in the little 6-gallon tank than the 115VAC at the
dock does. A whole lot of us can shower, making the whole crew MUCH more
socially acceptable in the process, during the battery charging phase
under Perkins Power. It only takes it a few minutes to recover and scald
the next victim in the head....or on the deck if no women object.

The Atomic 4 should make a LOT of great heat to heat the water tank. Why
do I suspect we're not actually forcing the heat through the water tank's
heat exchanger right?? The gas engine is more inefficient than diesels.

??????