120V appliances

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During the renovation of an egg sometimes new appliances are a necessity...

Since 120V appliances cost much less than 12V or specialized 3-way ones,

1. Is it cheaper just to replace/retrofit older appliances (like Dometic refrigerators) with plain 120v ones (say, from Walmart)? This'd probably require a large inverter which is expensive.

2. Or is it cheaper simply to get the expensive Dometic/Norcold 3-way refrigerators and deal with other 120 volt stuff like a microwave oven when shore power is available.

3. If shore power is available most of the time (unless one is boondocking without a generator), then why even need propane-powered appliances? Of course generators are noisy and take away from the tranquility).

4. What is the frequency of use for each appliance (in an avg. hookup-capable campsite situation) and what is the commonest mode of power used? Just to re-visit the appliance choice question.

5. Of course one can go back to to the 'minimal camping' level and use these (to solve lighting problems for example), the last one is still used in parts of the world as a primary source for lighting...

<img src=http://www.fiberglassrv.com/board/uploads/3eb971e361a5clantern.jpg/>

<img src=http://www.fiberglassrv.com/board/uploads/3eb971ec2ecc6old lantern.gif/>

<img src=http://www.fiberglassrv.com/board/uploads/3eb9721ff0bdcbatt lantern.jpg/>

<img src=http://www.fiberglassrv.com/board/uploads/3eb9736544163wtk2.jpg/>

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Refrigerators just don't run well off an inverter. I've tried it with multiple fridges and multiple inverters (including a very large one). It works for a while, and then just quits at the worst time.

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In that two/three hour time what does it run off of? Propane?

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Propane or 12V, depending on if you have a 2-way or 3-way. There is a lot of discussion about the merits of going down the road using propane. You'll have to decide that for yourself.

I've found that inverters are ok for non-sensitive solid-state devices. Not so good for extended use of motor-driven devices, such as refrigerators - can damage the appliance as well as the inverter. I still have one in my camper, but use it only for emergencies. Some folks boondock extensively and have found ways to live with inverted power. We almost always have electricity when we camp, so I have 110v microwave. Refer is a 2-way, and I drive on propane, with appropriate precautions.

Incidentally, I sleep with a C-PAP machine to help with sleep apnea, and my machine is specifically designed for rv-ers. It has filters and logic circuitry specifically so that it can be run on an inverter - it disguises itself as a solid state device, so the inverter won't "feel" the motor. Interesting. Haven't tried running it on the inverter to date.

[Legacy Posts]

Hi Paul, I use an old fridge out of a Starcraft pop up in my Boler and it uses a heating element and I use a 400 Watt inverter while I`m towing and switch to propane when parked. I tried to run off the inverter overnight but my battery ran out at about 3 AM. So that wasn`t too good. I don`t like using propane overnight in my Boler because the stove vent window is over the fridge vent and I leave it open for circulation and woory about Monoxide or co2 getting into the trailer. Now have a battery powered detector so will run propane at night. But the gist of this was that with a resistor (heater) no problem with the inverter at all during the day....You have a compressor fridge I gather?? Benny

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I have a three way fridge, and the only time I use it on 110 volt is in the driveway for the day before I leave. Even when camping where power is available I prefer propane. The fridge runs better(or seems to) , and the heat from the propane seems to keep the condensation out., Now for water, last year I bought a Lighning rod kit for my water heater. It converts a gas only water heater to gas/110 volt.
This little beauty I love, it takes only about 10 minutes to heat the tank from cold to usable and has a fast recovery time.
It's an easy upgrade, it took me about two hours tops, and I'm kind of finicky for looks even of technical stuff. For lighting, I only have 12 volt anyway.

[Legacy Posts]

.....do you know of any RVs that come with '120vac only' fridges?

go figger! :)

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Bill:

It's not the "cost of the inverter" so much as you'd need all the floorspace filled with batteries in order to run the fridge on 120vac.

....not really, but you get my point?! :)

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Well I _am_ a rank newbie at this so this is the only way for me to find out :)

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Orginally posted by PineConeDon

.....do you know of any RVs that come with '120vac only' fridges?

go figger! :)

Howdy, Wondering what this is question is in reference to? I have a fridge that is 120V or propane-No 12 V. And I believe Bill was probably refering to a koolatron or a bar fridge. If an inverter would power the bar fridge during travel and use 120 v in the campsites then you could probably do just fine......Benny

[Legacy Posts]

FWIW, 99% of the inverters put out a modified sine wave, which is basically a fancy 'square' sine wave. These don't work well with inductive loads. Motors like those used to drive compressors, battery chargers, etc are inductive loads. The other type load would be resistive.

Electricians refer to something called 'power factor' which indirectly refers to the efficiency of an AC device to use the current presented it. Normal efficiency is somewhere around 80 to 90% on a motor plugged into your home outlet (pure sine wave). With a modified sine wave current source, efficiencies of 40 to 50% are not unusual. That suggests that an inverter would have to be sized twice as large (or more) as the load from the motor. The compressor motors on reefer units are probably being 'starved' to death.

Some more expensive inverters (ProSine, Trace) output a (nearly) pure sine wave and don't have to be so over sized.

<img src=http://www.fiberglassrv.com/board/uploads/3eba4aa3a20cdi_sinewaves.gif/>
(From Sierra Solar web site)

This modified vs pure sine wave is another reason RV magazines will often advise users to sum up current usage and then double it when sizing a generator. Most generators produce a modified sine wave.

Lastly, this is why the small Honda (and some Yamaha) generators get away with powering air conditioners on our little trailers. These particular models, often refer to themselves as using 'inverter' technology. Their inverters are putting out (nearly) pure sine wave current.

[Legacy Posts]

Benny:

I meant that if a 120vac (only) fridge in an RV was a good idea, why don't some RV manufacturers use the cheaper fridge?

Looks like Steve answered that!

The cheaper 120v home fridges are cooled using a compressor.

2 or 3 way RV fridges don't use a compressor. What is it, 'heat absorbtion system' or something.....I dunno, but it seems to be the way to go, even tho more $$$.

Perhaps vibration during travel is a consideration also?!

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Hi Bill:

Have you tried the 'links' button on the 'home' page? It'll connect you to lots of other good information.

Ain't it fun?! :)

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Yes more money but you dont need electrical power. just a heat source and with that i close my mouth :chatter

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Pineconedon,

Appreciate the explanations. I found out 3-way refers are indeed cooled by ammonia absorption process, either by

1. an electrically heated element (12v DC or 110v AC)

Or,

2. a Propane heated element

In the case of propane, the pilot in the back has to be lighted, right?

Granted these are inane questions for anyone who's owned an RV -- but if it brings one more Fiberglass egg owner into the fold ...:)

[Legacy Posts]

cabin models have been around longer then your ac refigerator:wave

[Legacy Posts]

Orginally posted by PineConeDon
2 or 3 way RV fridges don't use a compressor. What is it, 'heat absorbtion system' or something.....I dunno, but it seems to be the way to go, even tho more $$$.

Perhaps vibration during travel is a consideration also?!

Hi again ...just thought that I would throw this in....I converted a bus in 74 and used a RV fridge in it that had a compressor. These fridges were also used in the GM motor homes of the period. The fridge was a two door 7.7 cu. ft. by Norcold. It ran on 43 V. It had a converter and inverter built in. Ran on battery or 110 V. power. Whatever was on at the time. IF it was plugged into 110, and batterywas hooked up it ran off the 110 and if you pulled the plug on 110 it automatically switched to battery.....The beauty part was it didn`t need leveling..and I carried 2 8D batteries....I checked the Norcold site some time ago but they are not available...could be the price as they were quite expensive 25 years ago.....Benny

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Bill:

The 16' Casita comes with a 2cu ft fridge with manual controls. Yes, you have to go outside and light the pilot. An automatic ignitor can be added, but you still have 'outside' controls.
<img src=http://www.fiberglassrv.com/board/uploads/3ebb1a88ce7fbCasita recepticle.jpg/>



The 17' Casita comes with a 4cuft fridge (with a freezer) and automatic controls (inside).

An additional note: the hot water heater comes with an option called DSI (Direct Spark Ignition). Allows you flip a switch 'inside' to get it going. :)

[Legacy Posts]

Thanks for the details PineconeDon. :)

And the photos too.

I'm guessing when they talk about electronic ignition in these appliances -- they're talking about piezo-electric ignition.

[Lloyd (aka Santa) Coltman]

Some of the newer Norcold and Dometic fridges have no pilot, and use direct spark ignition (lower gas consumption, too). Not sure how small they go with this feature, but the flame sense and auto shut off/alarm on the new units make 3-ways redundant, you just have to remember to TURN THEM OFF, when re-fuelling. They were always marginal on 12V anyways, and you better turn to gas if your engine would be off for more than an hour, or 'Hello,AAA?' The original fridge in my Layton was a 3-way, but it used the same 'micro' switch for either 115v or 12v, and the current at 12v (almost 10 x) cooked the switch. Then, instead of correcting the problem by replacing the switch, and slaving a relay for the 12v heater supply, they added another thermostat (at the back) and disabled the 12V. As the unit was pilot light type, you couldn't depend on it (almost never) to stay lit on the road. So, on a trip across the continent, I installed a 400watt inverter, to operate the fridge on the road. This remedy worked fine until the element shorted and blew the inverter. Then I operated it on propane only for the balance of the season, replacing it with a new 'Norcold' 5.5 cu ft over the winter.
BTW, I also use a 'CPAP', but mine is a two-piece unit, with the pump running at 12v(DC), and only the humidifier requiring 115V. I run 4-5 days on battery, without recharge, when 'Booning'