Heating and Cooling on the road

[Mile_High]

I'm probably a little naive on this coming from a 5th wheel, but when rolling down the road with passenger is a class A, are you pretty much stuck with the generator running the whole time to cool behind the cockpit? Or will the inverter operate any of those 3 AC/heat pumps?

[Kayteg1]

2800 inverter sure sounds like big enough to run single AC, but is your alternator big enough?
Constant speed generators are known gas-guzzlers so running one is not very economical, unless you have inverter model.
Than taking 1 HP from the engine is not noticeable even on compact car, where in our cars we don't see mpg change from winter to summer, when AC is on 100% of the time.
Manufacturers don't wire AC to inverters as there is too much involved, but in my conversion, where I have 8000W alternator, I do run AC from inverter just fine.
Make sure inverter is having good cooling as that become small issue with mine.

[tatest]

Depends on your budget.

$100,000 to $300,000 Class A, the independent generator is there to operate all your high-load electrical appliances, that includes the roof A/C units to cool the cabin. Toward the upper end of that price range, you might have an inverter large enough to run a roof A/C, and an alternator in the 300-400 amp output range to feed it.

Move up to $800,000 to $2,000,000 and the systems can change, with more being powered by the prime mover. Whole-coach A/C running off the engine is a possibility, as on passenger coaches, but more often you will still find room air conditioning units, three to five of them, to better manage climate in different parts of the coach. A diesel genset will still usually be provided for power when not moving, as an alternative to running a 400-600 HP engine at idle to get 8-12 KW of power.

Heating can come from LPG forced-air furnaces or hydronic systems using engine waste heat, usually supplemented by a fuel-oil fired boiler, which borrows your road-taxed diesel fuel.

There are also all-electric coaches which have a large electrical storage capacity, combined with high alternator output and an independent supplemental generator.

[tlaffourtit]

we can also run both a/c units if we choice too. If it's just the wife and I the ford a/c seems to be enough. When there are more people I can run the a/c unit with my inverter. I have solar which will produce between 90-97 amps on a sunny day.(which is when you would need to run the extra a/c unit. The alternator makes up the difference. most of the time I am still charging the batteries as we are driving down the road. idling sometimes we will be even or lose up to 15 amps

[Mile_High]

Unfortunately the hydronic equipped units were out of our budget, so this one will have 3 heat pumps and 2 LP furnaces that somehow coordinate with each other through one thermostat.

[DrewE]

The main engine is using perhaps around seven or eight gallons per hour driving down the highway (of course that depends on many variables). A generator uses less than a gallon an hour when powering an air conditioner, typically. The impact on overall fuel milage is a few percent.

For heating, you have a few more options, depending on how the unit is equipped. There's the dash heat, there's sometimes auxiliary heat off the engine coolant (possibly via a hydronic heat exchanger system), there's the propane furnace that does not require the generator to run, and there may be electrically operated heaters or heat pumps of various sorts that require the generator. If you can use the engine heat, dash or otherwise, it's essentially free as it would just be pulled out of the engine radiator if you didn't use it.

[nma33]

Seems to be somewhat of a trade off between running generator at about .6 gallons an hour or reduced MPG running the dash AC. For us we run the generator, I would rather have the entire coach cool and better power from my V10.

[pianotuna]

Hi,

I can run the roof air from my inverter--but I found out that using it on the fan only setting helps to distribute the dash air output to the rest of the RV.

[MaverickBBD]

Remember it is always easier to keep it cool then to get it cool. If you cool down the inside before departure and close off everything behind passenger compartment (bedroom, bath etc) you should be able to keep it cool with dash/chassis air. Start generator before you stop and turn off engine to run a.c. Otherwise you are stuck running running the generator down the road for a.c. Usual amount of fuel comsumption is roughly 1/4 gal/hr.

[Mile_High]

Ah thanks all - it was the fuel mileage I was concerned about. I had no idea how much they drink and was thinking it would pull a lot worse. I'm used to an LP generator. The A we are signed up for is the 8K diesel. The inverter is a 2800 but I think its sized for the fridge.

Excellent reminder to check the dash AC - I don't think I ever did.

[Valkyriebush]

My Chassis AC does fine as long as your in the front seats. If it's really hot out side 90 plus, I run my generator happily and whenever I feel like it. Surely not a burden or a negative. Uses a little fuel but that's the price of comfort and why I have a generator. You'll know what works for you.

[Ivylog]

Most run their generators, BUT I rarely have to run the generator to stay cool and NO you cannot run a AC off the inverter... they are not on the inverter's 120V circuits. One of the problems with the dash air is the hot water valve rarely shuts off all of the hot water... I installed a manual valve that I close in the summer. I also bypassed the evaporator temp switch so my compressor runs all of the time when AC selected... never defrosts. Out west I rarely have to shut the AC off to melt the ice buildup which slows the flow of air. When I know it's going to be 95+ I turn the front AC on and open all of the front vents (close all of the rear) so if the dash air cannot keep up, all I have to do is press the generator start switch on the dash IF it gets too warm. Closing the door to the back also helps to keep the engine heat in the back.

If I have to run the generator, then 30 minutes before getting to a CG with 50A service I'll have the DW turn on the front two AC's to start cooling the MH off. Otherwise it's going to take a while to get comfortable at the CG even with the door to the rear closed.

[Busskipper]

Mile High wrote:
I'm probably a little naive on this coming from a 5th wheel, but when rolling down the road with passenger is a class A, are you pretty much stuck with the generator running the whole time to cool behind the cockpit? Or will the inverter operate any of those 3 AC/heat pumps?

For the most part the Dash A/C will work as you drive down the road. (if you buy used that would be important to be sure the dash air still is GOOD - it is a weak point on many "A's") but if you need the Air on a day going across Utah or in the Foothills of Colorado you will need to run the Generator - we have found it uses maybe .6 gallons per hour so IMHO is not a factor.

Your Inverter is usually only sized to run the minimal Kitchen Micro or TV, unless you opt up to a larger 2,000 - 3,000 watt unit.

BOL on your search - you will find that it is Totally Different in a good way from the 5'er.

JMHO,

[Effy]

I would never say "stuck with the generator". That's what it's there for. Your own on-board power supply to run AC, TV's, etc. One of the reasons I bought a class A was to have a rolling apartment and all the comforts it offers. So yes, generator. We run ours pretty much 100% of the time when travelling. Especially in the summer. My wife and son cook food in the microwave, watch TV, all while the central AC keeps us cool. Fuel impact is negligible. Might detract .5 mpg. Your dash AC will likely hamper your engine that much and won't offer any cooling to anything 3 feet behind you. Your inverter will not run the AC.

[Bumpyroad]

If you cool down the insides before leaving the campground/unplugging from 120 v, the dash air maintained an acceptable temperature. I don't remember ever running the gen set in route to run the aC. Also since I stopped for a short rest every hour or two I would run the generator at the rest area, etc. to cool things down.
bumpy

[donn0128]

Generator.