Ducted furnaces running on batteries and cold weat

I am looking for an RV to use for both summer and winter use. I am looking at older units, 78-88ish. A or C isn't an issue.
My question is, since I will be gone from the MH for a whole day leaving in the morning and comming back in the evening 12 hours later.
With a ducted furnaces fan using battery power how long will a battery typically last? Temps can be as low as single digit hi's so even just trying to keep the coach at a minimum temp will require the furnace to run a lot. I plan on insulating ceiling vents, outer walls under cabinets and some sort of window coverings to minimize heat loss to help out.
How long would a battery last if it was a typical 750 Ah deep cycle?
Will I have to fully charge the battery every morning and night or will it last 2 or 3 days?
Will the furnace work if battery power drops very low, ie almost dead? A non ducted furnace seems the simplest but they are only in pretty small Rv's and I would like something in the 22-27' range.Will a ducted furnace work for me at all or should I lok for non ducted units only?
Ducted furnaces running on batteries and cold weat

After reading your letter, I would have to assume that you have little or no expierience with RV's. Most RVs are not designed for extreamly cold conditions. Your water lines and holding tanks tend to freeze and break for one thing. Most older coaches were built with a minimum amount of insulation so trying to keep them warm while away would only waste your LP. It would also require several large batteries to run a ducted furnace that long because of the fan motor. If your battery voltage falls below 10 volts, a ducted furnace will not continue to operate!! If you are in an RV park with electrical hook-ups, or have a generator, the furnace will operate off the converter.
If you intend to rough it more often, you might be amazed at the amount of heat a non ducted heater can put out. Or a catalyitic heater might be the way to go. Just be sure to supply plenty of ventilation!!!!!!
Hope this helps
Ducted furnaces running on batteries and cold weat

You are correct in the asumption I have little experience with RV's.
Right now we use a 19' 1972 Vacationeer TT. I want a unit that will tow my truck, instead of the truck doing the towing, and is a little longer. I know I will have to reroute water lines and insulate outer walls under cabinets and ceiling vents and cover windows well to limit heat loss...this I am not concernad about and plan for.
The reason for the post was to see if I could use a ducted furnace and not kill the battery in a few hours and have to deal with that after I get back from the field.
My sort of travel wouldn't take me to a place where I have hookups so power would be from from the battery bank or generator.
Problem is most MH's I have seen in the upper end of my 22-27'or so range all use ducted furnaces.
We have dealt with frozen lines and tanks before in the TT and plan on taking steps to minimize this in the RV by rerouting water lines an insulating to minimize the freezing problem.
I want to know, or at least get some input, about if I should look solely at nonducted furnaces or just leave the oven door cracked and on low to keep the interior above freezing.
Ducted furnaces running on batteries and cold weat

Hmmmm! If you havn't purchased a motorhome yet, I would look into the older top of the line motor homes. They normally have a ducted furnace that runs off 120 volts. Nellie Belle is a 1979 Fore travel and she has all the bells and whistles. A decent Foretravel in the 1979 to 1985 range normally runs about 9 to 13 thousand dollars. They have amenitie that a lot of the newer ones would like to have. Ice makers, dicted het, built in blenders, micro wave stove oven fridge and generators. For instance mine has a set up where by when you are running down the highway the water is heated by the through a small heat exchanger.

C Nash

Senior Member
Ducted furnaces running on batteries and cold weat

No on leaving the oven on to keep the interior from frezing :eek: . Might want to look into some solar power system to help keep batteries boosted. I assume that you would not want to go away and leave a generator running. 6 volt golf cart batteries would also help. If it will be parked in the same place, some type underpining would help.