Go Back   iRV2 Forums > iRV2.com COMMUNITY FORUMS > iRV2.com General Discussion
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 11-20-2012, 12:16 PM   #1
Senior Member
Ford Super Duty Owner
Join Date: Nov 2010
Location: SoCal
Posts: 127
Heater fan current draw

I've looked everywhere in the info books that came with our 2000 Winnebago Adventurer G37, to try to determine the current draw of the furnace fan.
I just today found out that I need not run the Gen. to turn on the furnace, Duh! While reading another thread it was said that the heater fan on his unit is 12 volts. I went out and checked mine, guess what, mine runs on 12 volts also.
What I'm trying to find out is, just how much draw the fan will have on the 2 - 6 volt house batteries.
Last year at Quartzsite we fired up the Gen about 30 to 45 min. during the night and ran the furnace because the temp inside got uncomfortable.
Now that I know the Gen doesn't need to run just to run the furnace, I'd like to know how many hours we can use the furnace and not run down the batteries.

Piledrive is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 11-20-2012, 07:41 PM   #2
Senior Member
ronspradley's Avatar

Gulf Streamers Club
Join Date: Mar 2011
Location: Central Texas
Posts: 1,828
I do not know what the amp hour draw of your fan motor is, but as a general rule with good batteries, you can run the furnace during the night and charge the batteries up the next day. If you are saying you are not hooked up to electricity, then you would need to run your generator to re-charge your batteries. Hope this helps.


1995 Monaco Windsor DP 32'
1993 Gulfstream Sun Voyager DP 30'
Toad 1998 Honda CRV, 2006 Honda CRV
Life's too short to drink cheap beer.
ronspradley is online now   Reply With Quote
Old 11-20-2012, 07:55 PM   #3
Moderator Emeritus
Gary RVRoamer's Avatar

Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,635
It will vary by the make, model & btu rating of the furnace, but if you figure 5-7 amps you will be in the right ball park. A 20,000 btu furnace typically draws around 5 amps, while a 32,000 btu model is typically around 7-8 amps. You can easily see how the furnace can draw down a battery overnight if its cold and it runs a lot.
Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote
Old 11-20-2012, 08:25 PM   #4
Senior Member
Join Date: Feb 2012
Posts: 122
So lets say that your battery bank has 200 amp total capacity. You don't want to run them below 50% discharge, preferably you want to keep them at @ 70% capacity, so u have @ 60 amps for the heater fan. (30% x 200 amps = 60 amps available)

If the heater draws 6 amp, and the fan runs 1/2 the time, you could in theory run the heater for 20 hours.

Now the problem is figuring out how often the fan runs relative to time and outside temperature.

I know that in my RV with 25 degree outdoor temps, my system would run @ 10 mins every 30 mins to keep a 70 deg interior temp.

So my 2x12v battery (Group 27 - 85 amps) give me @ 170 total, x .30% discharge, would give me @ 50 amps to drain.

Since my fan is also 6 amps, running 20 minutes per hour, I could in theory run 24 hours. But you generally only have to heat like that at night, so I could in theory go 2 days before recharging.

I hope this helps, IAN...
IAN (houseboats are RV's on the water)
1988 Amera Coach 23ft, dodge 360, Onan 4k
imorton is offline   Reply With Quote
Old 11-20-2012, 08:30 PM   #5
Senior Member
DonDee's Avatar
Join Date: May 2012
Location: Spring Valley AZ
Posts: 1,209
My 30K btu Suburban is rated at 4.5a. I measured it and it draws 3a. The amperage should be on a plate on the furnace.
Don, Mary and Spooky
'00 Bluebird Skoolie Conversion
Geo Tracker/Dodge Neon/Aprilia Scooter towed
DonDee is offline   Reply With Quote
Old 11-20-2012, 10:03 PM   #6
Senior Member
Join Date: May 2002
Location: Idaho Falls, ID, USA
Posts: 428
My outfit is in storage but if I remember correctly it is 40,000 BTW and the fan draws 11 AMP. Like it was said before the numbers should be on the furnace nameplate data, or call the Manuf with the model #.
2005 Dodge, 2500, auto, 2wd. Pac brake PRXB. CB, Max Brake Brake Controller, Rhino Lining, Aero 60 gal. replacement tank.
1998 Hitchhiker ll, mod#31RLBGBW, RBW L'tl Rocker Hitch, Generac NP50 G generator
richardcoxid is offline   Reply With Quote
Old 11-20-2012, 10:29 PM   #7
Senior Member
BFlinn181's Avatar

Gulf Streamers Club
Join Date: Jan 2012
Location: Cincinnati
Posts: 17,885
The only time I had an issue with running the furnace all night was when a visitor had flipped the compartment light switch on. I woke up about 2 am and heard the fan running really slowly. I had to start the generator and run for an hour. Now I have an LED indicator light on the dash that shows when the compartment light switch has been left on. You should be able to use the furnace through the night if you started with charged batteries.

Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI
BFlinn181 is online now   Reply With Quote
Old 11-21-2012, 04:37 AM   #8
Senior Member
J Birder's Avatar
Join Date: Feb 2012
Location: Lake County, IL
Posts: 1,244
I got around that problem by installing a catalytic heater in the bedroom area. It uses much less propane than the furnace and zero electricity. It won't warm the whole 5er, but it keeps us toasty warm in bed. You need to keep a window cracked, but we open one at the far end so it doesn't interfere with our heating.

Mine is an an Olympian Wave 3, but there other brands and there are also larger Olympians. If you expect to use it at high altitudes, check out the specs. The low oxygen sensors on some brands will turn them off at around 6,000 ft.


Retired electronics engineer. Avid paddler & birder.
2011 Silverado 2500HD, diesel, 4x4,crew cab, 8' bed
Palomino Puma 253FBS (27' 5er) & '94 19' Class B
J Birder is offline   Reply With Quote

fan, heater

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 02:09 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.