Refrigerator

There are 2.3.2 types of Refrigerators used now days in RV's

1: Absorption Cooling Units..

These are refrigerator/freezers that actually run o heat They can be Propane only (Which is actually a residential unit) Propane/Electric 120 volt (Very common and Propane/Electric 120/12 volt (Becomming more and more rare for the 12 volt option did/does not work that well.

They work by a series of chemical reactions and are powered by a heater... I won't describe it fully but the technology is older than my 65 years.. My Maternal grandfather worked with it in his prime in fact (he died before I was born).

The 2.2 types are electric only fridges.. One is the common Residential like you have in yoru sticks and bricks, It draws from 100 to around 4oo watts of electricity running, bit more for the fraction of time it takes the compressor to start.. This works by compressing a gas till it turns liquid, cooling the very hot liquid in a heat eschanger, then allowing the high pressure liquid to spray out into evaporative tubes which get very cold. Your home fridge will nto do this but a friend of mien worked on a system that uses this technology and hits sixty below (F).. next.

There is a new version of this, Comes in both Residential, RV and "other" formats (Mine is a chest freezer at the moment) This uses a compressor just like the traditional Residential..... only mine draws 36 watts.. The Dometic and Norcold RV fridges using this technology are below 50 watts with the doors closed (Amazing that opening the door makes that big a difference you have to specify) These run on 12 or 120 volts.. Mine is running on 12 cause that is the easiest feed.

Folks looking for a new/different RV refrigerator now have a choice closer to, IMHO, "the ideal".

If your RV has room for it, here it is - propane or 120V powered absorption technology ... AND 12V or 120V powered compressor technology:

http://www.motorhome.com/rv-travel-news/its-a-bird-its-a-plane/

Sam Spade wrote:

garmp1 wrote:
TI think most units are AC/DC. OK I get that. There is also a propane/AC/DC unit available.

Not true.
Most units are AC/propane.
DC operation is an expensive option that isn't all that useful because of the high current draw.

This is true; AC and propane are the commonest RV fridges by far. Nearly all these days do require DC power for control circuitry (both when operating on AC and on propane), but the DC power does not operate the cooling system.

A few mostly (maybe entirely) older RV fridges don't have a DC powered control and ignition system, but use a standing pilot light and some mechanical thermostat or other means of controlling the flame, and these do not require DC power. I don't know offhand if there are any like that in current production.

Sam Spade wrote:

garmp1 wrote:
TI think most units are AC/DC. OK I get that. There is also a propane/AC/DC unit available.

Not true.
Most units are AC/propane.
DC operation is an expensive option that isn't all that useful because of the high current draw.

the AC/DC/Propane fridges in DC mode pull a tremendous amount of power. If you want to run a fridge on DC, you would be better investing in a DC Compressor fridge.

Advantages of the DC Compressor Fridge:
- no propane
- uses less DC than the AC/DC/Propane models in DC mode.

Disadvantage
-you still need plenty of solar and batteries.

Unless you have some issues with using propane on the fridge or you are doing lots of boondocking (i.e. 70%+ of the time you are using your rv you dont have hookups when you camp), the AC/Propane models are just fine.

garmp1 wrote:
TI think most units are AC/DC. OK I get that. There is also a propane/AC/DC unit available.

Not true.
Most units are AC/propane.
DC operation is an expensive option that isn't all that useful because of the high current draw.

LrnnandCarol did a great job answering your question. I will add that when we purchased out TT I was hoping to find a three way frig. I ended up with a AC/gas unit. I do not miss the DC option. I operate on gas when traveling and it switches to AC when on shore power. The gas cunsumsion seems small to me. There are some that are not comfortable using gas when traveling but I feel they are the minority. There probably is less of a potential for something to go wring traveling with DC. Your call.

They usually have an "auto" setting and will automatically select electric if you are plugged in and will automatically switch to propane if the power goes out.

Normally a DC/Gas/AC Fridge will have a smart option. When going down the road it will be on DC, when it detects shore power it will switch, then you can manually put on gas if boon docking.