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Old 12-15-2012, 11:43 AM   #1
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Join Date: Apr 2011
Location: Southwest Florida
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I need some electrical help re furnace amp draw

My Atwood furnace manual lists my 7900-II as drawing 3.4 amps. The Jayco manual lists the furnace draw at 12 amps. We have done all our camping plugged-in up to now so it has not been an issue for us. Next year we have some boondock trips planned.

I'm trying to figure out what my DC amp draw is for each component so when I replace my battery I can calculate what I'll need in amp hours. I know the furnace doesn't run continuously, but the difference betwwen 3.4 and 12 amps per hour makes a big difference when buying a battery. How would I go about finding the actual furnace draw?

Everything else, right down to each light bulb, has been easy to find.

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Old 12-15-2012, 01:08 PM   #2
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12 amps sounds alittle high as the usual rule of thumb is 6-8AMPS. I just looked at the Technical sheet for the ATWOOD 7900 series unit and they all list it as 3.4AMPS so if you are sure of the heater part number then I would go with the 3.4 number.

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Old 12-16-2012, 09:09 AM   #3
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Round up and call it 4 amps...
when you replace your battery make sure it does not have a CCA rating... you need a true deep cycle battery ... if you have the room and $$$ 2-6 volt golf cart batteries work best (hooked pos to neg to give you 12 volts)
2004 Chev Silverado Duramax optioned past the max. 2009 Jayco Eagle 308 RLS 765 watts of solar, 6-6 volt batteries (696 amp hour), 2000 watt (4000 surge) whole house inverter.
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