Heater- 12vdc or 120vac

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99WinAdventurer37G

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On a recent trip I had my generator running and my heat on.  As with my AC I turned off the heat at the thermostat and then the generator.  With the generator off the fan for the heater continued to run for a few minutes.  This got me to thinking. 
1.) Do I need to run the generator with the heat on?

If so,  It has the standard three deep cycle RV batteries under the steps in at the MH entry door. 

2.) How long could I expect it to run before I'd need to run the generator to charge the batteries back up? 


I have a 99 Win. Adventurer 37g with basement heat.  It has propane heat.  Although I have two thermostats, only the one in the living room has a heat option.  The floor vents are both in the bedroom and throughout the MH. My main use of the unit is boondocking at my farm.

Thanks,
  Steve
 

Garyk

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Unless you have a heater that is really different, they run off 12 volt. The fan will stay on when you shut off the heater until the heater cools to a certain temperature. There is no need to run the generator as the engine alternator charges the house batteries when running.
An added thought, did not ask if this was a heatpump heater , in that case it will require AC current, but if its the propane heater, 12 volts.
 

Wizard46

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The heat pump function requires 120V from the generator, the furnace requires 12V from the batteries and propane. If the furnace kept running the the furnace was on. The propane furnace will automatically come on to augment the heat pump when the temp exceeds about 6 degrees below set-point.

Not sure if that's the way your system operates as you stated you have two thermostats. Mine only has one and it controls both.

Jerry
 

afchap

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My front t'stat controls the ac/heat pump and an lp furnace up front.  A second t'stat in the bedroom controls a second lp furnace in the bedroom. You don't need the generator to run an lp furnace.
 

Gary RV_Wizard

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Well, eventually you will need some way to recharge the batteries that power the furnace fans. They suck quite a bit of power - typically 5-6 amps/hour whenever the fan is running. How long the batteries last depends on their amp-hour capacity and how much the furnace fans run.
 

99WinAdventurer37G

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Thanks all.  I'll have to take some measurements then to find out what I need to know. 

But it's good to know I can turn it on to "take the chill out" before I go to bed.  Then turn it on in the morning when I get up.  After I get those measurements, I'll know if I can leave it on overnight. 
 

Garyk

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Some friends of ours were traveling in the cold weather with a TT and stopped for the night without hooking up. Ran the heater all night....woke up to a dead battery not only in the TT but the tow vehicle as well.
 

Wizard46

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That's why I always unplugged from my tow vehicle when parked overnight.
 

99WinAdventurer37G

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Garyk said:
Some friends of ours were traveling in the cold weather with a TT and stopped for the night without hooking up. Ran the heater all night....woke up to a dead battery not only in the TT but the tow vehicle as well.

I believe there are three "house" batteries that are deep cycle, then one start battery.  As far as I know, the house batteries can be run completely dead, and the motor  home will still start off the starting battery.  The only way they are connected, is if the starting battery is dead, there's a switch I can use to jump the MH off the "house" batteries.
 

Alfa38User

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Quite true for your motorhome 37G, but  GaryK mentioned  his example was a tow-behind trailer. If there was a charge lead run to the trailer so the trailer batteries would charge from the tow vehicle while under way, then all bets are off. The Tow vehicle battery would have to be isolated from the trailer (perhaps using isolation diodes) or the trailer unplugged to prevent discharging the engine battery. The required diode isolation is often missing.
 

99WinAdventurer37G

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Alfa38User said:
Quite true for your motorhome 37G, but  GaryK mentioned  his example was a tow-behind trailer. If there was a charge lead run to the trailer so the trailer batteries would charge from the tow vehicle while under way, then all bets are off. The Tow vehicle battery would have to be isolated from the trailer (perhaps using isolation diodes) or the trailer unplugged to prevent discharging the engine battery. The required diode isolation is often missing.

Thanks Alfa38User.  I wasn't sure that was correct, which is why the phrases "I believe" and "as far as I know" were used.  Thanks again for confirming that belief. 

I'm still kinda new to all this, but have done lots of boondocking with the unit so far. 

My next project is to build my pad, septic dug, and have the electric run to use this as my office out there.  But at this time I'm using the heat more than the AC, so during the day the generator fills the batteries, then I use the heat before I go to bed, then first thing in the morning.  We've been having days in the 80's, nights in the 50's.  And as Gary has mentioned many times on here, these RV's don't have the insulation of a sticks and bricks house. So I work out both the heat and the AC.
 

Jammer

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99WinAdventurer37G said:
If so,  It has the standard three deep cycle RV batteries under the steps in at the MH entry door. 

2.) How long could I expect it to run before I'd need to run the generator to charge the batteries back up? 

Typically the larger propane heaters draw 10 amps.  With Group 27 RV batteries you'll get, realistically, about 6-7 hours of furnace runtime per battery.

 

Jammer

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Garyk said:
Some friends of ours were traveling in the cold weather with a TT and stopped for the night without hooking up. Ran the heater all night....woke up to a dead battery not only in the TT but the tow vehicle as well.

Tow vehicle wiring varies widely with most new pickups now being shipped with the charge line either completely disconnected or wired through a relay that is only on when the ignition switch is on.

I have an extra deep cycle battery under the hood of my tow vehicle that is connected to the charge line, to provide more 12v power to run the furnace when dry camping.  That way if we unhitch and go on side trips during the day the battery recharges from the alternator in the tow vehicle.  There's an isolator relay between that and the chassis (engine starting) battery.
 
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