propane furnace on while towing

[rlh1957]

You’ll be heating a rig you’re not in. Burning up propane with a monster, the furnace had a big appetite.
Daytime travel you’ll benefit from some solar heating of rig.
I’ve never had pipes frozen when arriving at site.

[ChuckS]

So much incorrect info regarding the furnace and RV style fridge and worries about gas flowing if they don't stay lit

The furnace and the fridge will both go to LOCK OUT mode if the control boards for each don't receive feedback indicating a flame is present..

Lock out mode has to be CLEARED by turning off either the fridge or furnace and starting again

That means... NO LP FLOW..

Suggest some read the manuals on how these appliances work ..

Bad info just adds to the confusion for some RV owners..

I have towed probably 100K miles running LP fridge.. I have also towed with the furnace ON when I got caught in unexpected freezing temps ( 20 degrees and colder )...

[travelin texans]

Originally Posted by ChuckS

So much incorrect info regarding the furnace and RV style fridge and worries about gas flowing if they don't stay lit

The furnace and the fridge will both go to LOCK OUT mode if the control boards for each don't receive feedback indicating a flame is present..

Lock out mode has to be CLEARED by turning off either the fridge or furnace and starting again

That means... NO LP FLOW..

Suggest some read the manuals on how these appliances work ..

Bad info just adds to the confusion for some RV owners..

I have towed probably 100K miles running LP fridge.. I have also towed with the furnace ON when I got caught in unexpected freezing temps ( 20 degrees and colder )...

Agree too much false info! These safety factors have been in place for a lot of years.
Also the portable LP bottles have a built in check valve in case of any rapid release such as a ruptured line due to an accident will shut off the flow.
To test this next time you have the bottle filled quickly open the valve then try your cook top, I think you'll find it lights but will burn out in a short time. To reset close the valve, loosen the rubber line til you hear a slight gas release, reconnect the hose & open the valve slowly til.you hear the gas pressure the line, continue to fully open the valve. Always open the valve slowly!

[rlh1957]

Originally Posted by ChuckS

So much incorrect info regarding the furnace and RV style fridge and worries about gas flowing if they don't stay lit

The furnace and the fridge will both go to LOCK OUT mode if the control boards for each don't receive feedback indicating a flame is present..

Lock out mode has to be CLEARED by turning off either the fridge or furnace and starting again

That means... NO LP FLOW..

Suggest some read the manuals on how these appliances work ..

Bad info just adds to the confusion for some RV owners..

I have towed probably 100K miles running LP fridge.. I have also towed with the furnace ON when I got caught in unexpected freezing temps ( 20 degrees and colder )...

BRAVO! Excellent facts.
Many LP fears, old wives tales, misinformation is of the grapevine variety and no factual basis in this last 15 years. It comes from early LP tanks, valves and regulators used in earlier times without the safety features of today.
You’re on point!

[440scout]

Originally Posted by seanrmz

sorry I was not clear on the fridge voltage. Its a duel gas/fridge. It does not have a 12v compressor.

here is the draw fridge only running off the inverter and 12v battery

its my mistake I said 36amps but its 27 amps my bad.

https://photos.app.goo.gl/if65TgfJ9vhkYvMT6

That amperage draw is not so bad, the Nocold 18 cubic foot fridge in my s.o.b. 5th wheel pulls 44 amps from the 12 volt batteries through the 3000 watt Go-Power inverter-charger while running on 120 volts. That amperage is what is indicated on the inverter remote display panel. Of course during travel the 40 amp dc to dc charger covers most of that usage and the (1000 watts) solar helps but so does the few amps supplied from the 7 pin connection.
As for the possibility of a closed slide out covering the furnace intake-exhaust ports, I've never seen that and I suspect it would not be built to code and or safety regulations.

[chuckster57]

Originally Posted by 440scout

As for the possibility of a closed slide out covering the furnace intake-exhaust ports, I've never seen that and I suspect it would not be built to code and or safety regulations.

The combustion chamber intake and exhaust are on the exterior wall per code. The return probably isn’t covered but a register may be by a retracted slide (floor). My registers are in the middle of the floor so my slides don’t cover them, return is under the fridge (not in a slide).

[440scout]

Originally Posted by chuckster57

The combustion chamber intake and exhaust are on the exterior wall per code. The return probably isn’t covered but a register may be by a retracted slide (floor). My registers are in the middle of the floor so my slides don’t cover them, return is under the fridge (not in a slide).

Good setup! Would it be correct to consider an RV furnace direct vented? Unlike some residential furnaces an RV uses outside air for combustion. Even though an RV furnace is not very high on the efficiency scale (60-75%) like the 96% efficient residential furnaces it still doesn't seem so bad, although there are a lot of complaints about the high amperage of the furnace blower motor. The high efficiency furnace in my sticks and bricks has 2 heat exchangers and like an RV it is direct vented. The residential high efficiency furnaces can use PVC pipe for intake/exhaust. Because nearly all the heat that is created is transferred to the supply air, there is very little heat exhausted to the outside which is why they are able to use PVC pipe for exhaust. Sorry, I got way off track but just thinking of how a small high efficiency residential furnace could be adapted to an RV other than switching the blower motor to a 12 volt and rejetting or replacing the gas valve for propane.

[jasin1]

Originally Posted by 440scout

Good setup! Would it be correct to consider an RV furnace direct vented? Unlike some residential furnaces an RV uses outside air for combustion. Even though an RV furnace is not very high on the efficiency scale (60-75%) like the 96% efficient residential furnaces it still doesn't seem so bad, although there are a lot of complaints about the high amperage of the furnace blower motor. The high efficiency furnace in my sticks and bricks has 2 heat exchangers and like an RV it is direct vented. The residential high efficiency furnaces can use PVC pipe for intake/exhaust. Because nearly all the heat that is created is transferred to the supply air, there is very little heat exhausted to the outside which is why they are able to use PVC pipe for exhaust. Sorry, I got way off track but just thinking of how a small high efficiency residential furnace could be adapted to an RV other than switching the blower motor to a 12 volt and rejetting or replacing the gas valve for propane.

the main problem with a 90+ condensing furnace is the water produced in the exhaust pipe and secondary heat exchanger. They work very well in a conditioned environment but if you have them in a house or rv that is not heated and not occupied you have to take extra precautions to keep the furnace trap (not the air cond trap) from freezing and the internal pipes, also the vent would have to stick out a little from the rv because the gases are highly acidic.

the typical rv furnace is similar to a 80% efficiency residential furnace as far as having an inducer motor for the exhaust.

the cost difference between a 80% and 90% is significantly higher and take many years to recoup the money by the additional 10% operating costs…actually they are not the best choice unless you do not have a chimney in your house presently because of the complexity and additional components that can fail.

usually see on new construction or if the utility is offering energy rebates…one thing people don’t realize is that if you switch from a natural draft gas furnace to a 80% with an existing masonry chimney …you MAY have to add an aluminum chimney liner properly sized so you don’t ruin the masonry liner and cause a poor draft situation from the cooler exhaust gasses …anyhoo…back to our regularly scheduled program

[440scout]

Thanks for that very good explanation. From what I've seen most homes built in the last 60 years or so use a galvanized 6 inch steel vent or similar for the furnace. I guess a lot of older homes have those masonary chimneys. At least thats what I see here in Colorado.

[bobbecky]

The excess flow valve that restricts gas flow in the event of a leak is not in the gas cylinder valve but is in the attachment nut assembly that is part of the pigtail. It is a spring loaded ball bearing that closes off the gas flow, shown in the photo of a cutaway valve.

[kguess]

I go with heating things up 40 minutes before landing.

[travelin texans]

Originally Posted by bobbecky

The excess flow valve that restricts gas flow in the event of a leak is not in the gas cylinder valve but is in the attachment nut assembly that is part of the pigtail. It is a spring loaded ball bearing that closes off the gas flow, shown in the photo of a cutaway valve.

The tank also has one!
Remove the hose from your tank & open the valve, I think you'll find nothing comes out.

[GaryUT]

I have towed for years with the propane on to run the fridge. Never had a problem. None of our heat registers or the return are covered by the slides so running the furnace is possible, I've never done it because we normally don't use the trailer in the winter.

Last June we had a blowout on the trailer that damaged the propane lines, the excess flow valves functioned as intended and stooped the flow of propane.

Just use common sense when running the fridge on propane. Don't park the trailer next to a gas pump when fueling. If you have to shut it off for a tunnel or ferry, turn it back on when you get to the other end.

Gary

[seanrmz]

thanks everyone for your input. I made it to Florida safe and sound, the trip was great over 3 days. I did manage to get the fridge going on my house 400amp batteries ( charging with solar and a dc to dc 30amp charger running of the pickup)
As for the heat I warmed up the rv a few days before departure with space heaters. I kept the rv in the 40ies while on the road and with the app I brought the heat up to 30 min before taking a pit stop. We shut it down the next day for the rest of the trip since it was getting warmer and I did close the tanks.

thanks for all great info

sean