Should furnace blower run on 110 ?

[knuckleheadpower]

Sent: 12/12/2006

I have a 76 Brave. Shouldn't the furnace blower run on 110 when the camper is plugged in ? Is it dual voltage ? I think my furnace blower is tapping out my coach batteries.

[DanD2Soon]

Sent: 12/12/2006

Eron,

Your suspicions about the furnace running your coach battery down are probably correct...  They are 12Volt DC Negative ground, not dual voltage.

Suburban recommends that if your furnace power is supplied from a converter, it should "be connected in parallel with the battery."  They say this serves two purposes - 1.  Provides a constant voltage supply to the furnace - 2.  Filters any A.C. spikes or voltage surges.

I think they're right, but they're also "tip-toeing" around some other issues that aren't the furnaces' fault.  "Cleaner" power is less likely to damage the module (circuit) board inside the unit.  In really cold weather, the furnace runs almost constantly and many of the older converters can't keep up with the demand, so having them [Converter & Battery] connected in parallel allows your furnace to "borrow" what can't be supplied by the converter from your battery.  If your converter has a working battery charging circuit, the House Battery should stay Up;  If not,  you're probably gonna wake up cold with a dead  battery... Don't be tempted into using the dual setting on your Battery switch!  You'll just wake up cold with TWO dead batteries and no way to start the coach without a jump...

There are many threads in the message search library that can show you what others have done and help you decide what you want to do - Remember, You are NOT alone, it's probably happened to someone else here.

<=====  Just click Message Search on the sidebar.  Try keywords like "batt" or "charger" or "convert."

Keep us posted - update this thread with what you find & what you decide - we'll be watching and jump in whenever we think we can help - Good Luck - DanD

[denisondc]

Sent: 12/12/2006

Too make matters more confusing, the coach makers and furnace makers changed their designs periodically. The designs got more sophisticated in newer RVs.
In my 72 Winnie my furnace runs from 12 volts only. If the converter is on, it automatically disconnects the coach battery from the circuit - and the furnace runs from the converter's 12 volt output only. If the converter is switched off via its circuit breaker, (or its well hidden internal fuse), the furnace will run from the coach battery. But only until that battery is discharged, probably not even an entire chilly night. There should be a fuse panel somewhere for all of the 12 volt lights/fans/furnace/water pump. I don't think there is any standard location for that panel, except it wont be under the dashboard, where the fuses are located for the lights/horn/heater/turn signals/ etc.
Some of the later converters had provisions for charging the coach battery any time the RV was plugged into shore power (if the converter was still working properly). If you are lucky, no prior owner rewired things to try and make something work. When I bought my Winny, the furnace had been wired up wrong; which learned from staring at the schematic for a loooong time.

[LJ-TJ]

Sent: 12/12/2006

T.J. here...I am following this with a great deal of interest as L.J. and I have just returned from a trip and that's exactly what happened to us. Went to sleep one night and woke up freezing our bum's off. However the Winny started up just fine so it only drained the house battery.

[pinballlarry1]

Sent: 12/12/2006

Here's my rookie 2 cents based on careful inspection, but never having dried it up yet. My '71 has the original Coleman unit, see the photo on page 3 of my album.  The wiring terminal strip has 110 volt, 12 volt and thermostat connections.  The 12 volt and thermostat are wired up, but the wiring diagram shows an internal transformer to allow 110vac input when the toggle switch is moved to the right. My nameplate indicates about 8 amp draw when using 12 volts.