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Author Topic: How does a fridge work while I'm off-the-grid?  (Read 1057 times)

Angiekaye

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How does a fridge work while I'm off-the-grid?
« on: October 31, 2017, 03:00:37 AM »
So I've been living in my Rv for a few weeks now and haven't really used my fridge cause I don't know a lot about it. I don't have a place to hook up right now, so I'm living off the house batteries, generator in the RV and a smaller solar generator Yeti400.  My RV has a propane tank on it.

Here's what I know about the fridge. It works. It has a switch that says Electric - Off - Gas.  I can only use the electric part if I'm hookup right? And the Gas is only when my propanes on? If I were to use my propane, how long could the fridge last? It seems like the fridge isn't really usable for long-term boondocking, right?

Thanks!
Angie

Lou Schneider

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Re: How does a fridge work while I'm off-the-grid?
« Reply #1 on: October 31, 2017, 03:29:25 AM »
Gas-electric refrigerators work really well off-grid.  They don't have a compressor like a normal house refrigerator, instead they use a process called adsorption (or absorption) where you apply heat at one location to get cooling at another.    In electric mode the heat is provided by an electric heating element and yes, you have to be plugged into power (or running the generator) to use it.

But the refrigerator's native mode is using propane to create the heat.  It uses very little propane and your other propane uses (stove, hot water heater, furnace) will determine how often you need to fill the propane tank.  The refrigerator by itself can run several weeks to several months before it drains the tank.

The refrigerator also uses a small amount of 12 volt power to run it's control board, less than a single LED light.  Again, not enough to worry about - your other 12 volt uses will determine when you have to charge your battery.

The refrigerant is an ammonia and water mix that is heated in a boiler, then the ammonia vapor rises by convection to the freezer where it condenses back into liquid form and absorbs heat from the inside of the refrigerator.  Then gravity draws the liquid ammonia down to the bottom of the cooling unit, it is re-combined with the water and flows back to the boiler to begin the cycle again.

It's a very reliable process that has been around for about 100 years.

The weak point of the absorption cycle is the convection and gravity stuff.  The refrigerator MUST be within a few degrees of perfectly level for the refrigerant to properly flow through the system ... water won't run uphill.  If you operate it while the RV is off-level, the water and ammonia mixture won't be able to get back to the boiler and it can run dry and overheat.   If it does, it will create hard flakes that can plug the cooling passages, damaging or ruining the cooling unit.

« Last Edit: October 31, 2017, 03:09:43 PM by Lou Schneider »

halfwright

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Re: How does a fridge work while I'm off-the-grid?
« Reply #2 on: October 31, 2017, 03:31:44 AM »
Right, the fridge  Is useable on 120 volt only when hooked to shore power or running a generator.

Wrong, it will run on propane indefinitely. If it has not been run on propane for a long time, check to be sure the burner is clean and no obstructions in the flue.  Turn it on propane and you should hear the lighter click. Then, make sure you can see a small flame and the flue is hot.
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sadixon49

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Re: How does a fridge work while I'm off-the-grid?
« Reply #3 on: October 31, 2017, 08:58:07 AM »
The amount of gas used by a propane fridge is very small, about equal to a standing pilot lite on a stove or furnace. You could run that fridge for months on a single tank of propane. Your other uses of propane, water heater, stove, oven, etc. will determine how long your tank lasts. Take the fridge use into account for sure, but just no need to worry about it.
steve
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Great Horned Owl

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Re: How does a fridge work while I'm off-the-grid?
« Reply #4 on: October 31, 2017, 09:12:09 AM »
Right, the fridge  Is useable on 120 volt only when hooked to shore power or running a generator.

Wrong, it will run on propane indefinitely. If it has not been run on propane for a long time, check to be sure the burner is clean and no obstructions in the flue.  Turn it on propane and you should hear the lighter click. Then, make sure you can see a small flame and the flue is hot.

Perhaps. You will hear the light click if it is a reasonably new fridge. The older ones had pilot lights that you had to light manually. Some were a little difficult to get lit.

Joel
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Angiekaye

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Re: How does a fridge work while I'm off-the-grid?
« Reply #5 on: October 31, 2017, 12:20:13 PM »
Super helpful everyone. Okay, my goal this week is the get levelers under my tires so then I can start using the fridge. (I'm glad I know that about making sure the fridge is level before using). And I'm so happy I can start using the fridge now!!! And not worry about running the propane tank dry in a few days.

One more question: I have a habit of turning the house batteries off when I leave for the day to save battery. The propane and house batteries aren't connected are they? So if I turn off the house batteries, the fridge will still be on if I am using propane, right?

Great Horned Owl

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Re: How does a fridge work while I'm off-the-grid?
« Reply #6 on: October 31, 2017, 12:48:08 PM »
One more question: I have a habit of turning the house batteries off when I leave for the day to save battery. The propane and house batteries aren't connected are they? So if I turn off the house batteries, the fridge will still be on if I am using propane, right?

No! There is a control board for the fridge that operates from 12V. With the batteries off, there is no 12V, and the fridge won't function. Don't worry about the current draw. It will be just fractions of an amp.

Joel
Joel & Dorothy
Retired electronics engineer. Avid photographer, paddler & birder.
2011 Silverado 2500HD, Duramax, 4x4,crew cab, 8' bed
Palomino Puma 253-FBS  27' 5th wheel
1994 19' Class B Horizon / Chevy

Angiekaye

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Re: How does a fridge work while I'm off-the-grid?
« Reply #7 on: October 31, 2017, 02:10:00 PM »
ok gotcha!  Thx

ArdraF

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Re: How does a fridge work while I'm off-the-grid?
« Reply #8 on: October 31, 2017, 02:55:18 PM »
I might add that RV refrigerators take a while to cool.  We usually start ours two-three days before a trip and start loading it after a day with cold things that have been in the refrigerator for a while such as cold drinks.  I add the less-cool items closer to leaving.  Because you're parked for while I wouldn't add anything for at least two days and maybe even three to make sure it's really cold first.  We have small thermometers (Camping World and other RV stores) in each section so we know how cold it's getting.

It might be helpful if you let us know the make, model and age of items you ask about.  The two big RV refrigerator makers are Norcold and Dometic.  Some are two-door and some are four-door models.  Some also have Auto on the switch which you can set to automatically switch between electric (plugged in or generator) and propane when no electric is available.  When boondocking we tend to leave it on propane.

ArdraF
ArdraF
:D :D

Utclmjmpr

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Re: How does a fridge work while I'm off-the-grid?
« Reply #9 on: October 31, 2017, 06:08:11 PM »
  Lou..Why would anyone want to heat hot water??>>>Dan
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Lou Schneider

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Re: How does a fridge work while I'm off-the-grid?
« Reply #10 on: October 31, 2017, 08:13:51 PM »
Because it's not hot enough.  Duh.

Angiekaye

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Re: How does a fridge work while I'm off-the-grid?
« Reply #11 on: November 03, 2017, 01:41:36 AM »
Okay!  The refrigerator is a Norcold. I took a picture of the fridge and the details on the inside. But maybe everyone's familiar with this one.

My hope is to start using the fridge soon. My RV is now pretty level after driving my right 2 tires up on blocks, so I just need to turn the propane on and the fridge will work? My propane tank says it's 3/4 full. 

Lou Schneider

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Re: How does a fridge work while I'm off-the-grid?
« Reply #12 on: November 03, 2017, 02:35:34 AM »
Okay!  The refrigerator is a Norcold. I took a picture of the fridge and the details on the inside. But maybe everyone's familiar with this one.

My hope is to start using the fridge soon. My RV is now pretty level after driving my right 2 tires up on blocks, so I just need to turn the propane on and the fridge will work? My propane tank says it's 3/4 full. 

Yup, pretty much.  Make sure the valve on the propane tank is fully open, this seals the knob shaft against leakage.

You probably have some air in the propane lines if the system has been off for a while.  Try lighting a stove burner using a BBQ lighter - the burner may blow nothing but air for several seconds until the propane reaches it.  The reason for lighting the stove first is it uses much more propane than the refrigerator so it takes less time to purge the air out of the lines.

Then switch the refrigerator to Gas and see if it lights.  You should hear several slight clicks as the igniter lights the flame in the rear of the fridge.  The Check light should go out when the flame lights.  If the light stays on, turn the refrigerator off to reset the circuit board and try it again.

It can take several hours for the system cool the refrigerator.  First thing you'll feel is the rear wall of the freezer getting cold, after the freezer is cold, cooling will migrate down to the refrigerator.

BTW, the answer to how much propane the refrigerator will use is on the nameplate.  Propane contains about 90,000 BTUs per gallon and the nameplate says the refrigerator uses 1500 BTUH (BTUs per Hour).  That means it uses a maximum of 1/60th of a gallon of propane per hour, or 60 hours at full cooling per gallon of propane.

But the cooling system won't run full time unless you're in 100+ degree heat.  So you can stretch that figure by at least twice or three times as long in normal temperatures.
« Last Edit: November 03, 2017, 02:40:58 AM by Lou Schneider »

AStravelers

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Re: How does a fridge work while I'm off-the-grid?
« Reply #13 on: November 03, 2017, 03:50:43 PM »
...................It might be helpful if you let us know the make, model and age of items you ask about.  The two big RV refrigerator makers are Norcold and Dometic.  Some are two-door and some are four-door models.  Some also have Auto on the switch which you can set to automatically switch between electric (plugged in or generator) and propane when no electric is available. When boondocking we tend to leave it on propane.

ArdraF

A word of caution:
I am reading reports of Winnebago MH's (model years in the 2012-2016 maybe additional years as well) having the gas/elect fridge wired though the inverter.  So being on auto and just unplugging from shore power does not allow the fridge to switch to gas.  The fridge just drains the battery though the inverter. That is unless you didn't notice the fridge was still running on elect and switched it to "gas only".
Al & Sharon
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2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

WILDEBILL308

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Re: How does a fridge work while I'm off-the-grid?
« Reply #14 on: November 03, 2017, 09:10:41 PM »
A word of caution:
I am reading reports of Winnebago MH's (model years in the 2012-2016 maybe additional years as well) having the gas/elect fridge wired though the inverter.  So being on auto and just unplugging from shore power does not allow the fridge to switch to gas.  The fridge just drains the battery though the inverter. That is unless you didn't notice the fridge was still running on elect and switched it to "gas only".
I couldn't read the placard in the picture but I bet the OP won't have a problem with that. :))
Just wondering, Angiekaye have you got your hot water heater working?
Bill
« Last Edit: November 03, 2017, 09:15:09 PM by WILDEBILL308 »
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Gary RV_Wizard

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Re: How does a fridge work while I'm off-the-grid?
« Reply #15 on: November 04, 2017, 12:49:57 PM »
Quote
I am reading reports of Winnebago MH's (model years in the 2012-2016 maybe additional years as well) having the gas/elect fridge wired though the inverter.
I doubt if they come that way from the factory, at least not intentionally, but the fridge icemaker is usually plugged to an inverter outlet so as to allow the icemaker to work off-grid.  Sometimes the fridge electric mode heater gets plugged into the inverter outlet, either accidentally or because the owner wants to avoid LP gas mode while traveling. That's fine as long as the engine alternator is running, but not so good once you park.
Gary
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Angiekaye

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Re: How does a fridge work while I'm off-the-grid?
« Reply #16 on: November 04, 2017, 04:33:15 PM »
I couldn't read the placard in the picture but I bet the OP won't have a problem with that. :))
Just wondering, Angiekaye have you got your hot water heater working?
Bill

No, I haven't got the hot water running yet. I take showers at work right now and wanted to focus on getting everything running first. But I need to learn eventually:)

Trivet

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Re: How does a fridge work while I'm off-the-grid?
« Reply #17 on: November 04, 2017, 06:11:19 PM »
The amount of gas used by a propane fridge is very small, about equal to a standing pilot lite on a stove or furnace. You could run that fridge for months on a single tank of propane. Your other uses of propane, water heater, stove, oven, etc. will determine how long your tank lasts. Take the fridge use into account for sure, but just no need to worry about it.

I have a four-door Norcold refrigerator and it uses 1/2 gallon of propane a day, which is more than I expected.  Since the OP's refrigerator looks to be about half the size of mine, I'd make a wild guess that it uses about 1/4 gallon/day.

Angiekaye

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Re: How does a fridge work while I'm off-the-grid?
« Reply #18 on: November 04, 2017, 11:51:08 PM »
OK, I turned on the propane for the first time today. (I've been afraid I'd blow myself up:). So I turned it on, and lit the stove top to get the air out of the line (as someone suggested).  The stove worked great. But then the fridge wouldn't ever start. It tried. It kept clicking to try and start. The x would go on and off. Then I would try turning it off and on again. Maybe I'll try it again tomorrow and see how it goes.

Gary RV_Wizard

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Re: How does a fridge work while I'm off-the-grid?
« Reply #19 on: November 05, 2017, 08:57:29 AM »
Quote
I have a four-door Norcold refrigerator and it uses 1/2 gallon of propane a day, which is more than I expected

That does seem excessive. Are you sure it isn't a 1/2 lb rather than  a 1/2 gallon? The flame isn't much bigger than an oven pilot light.

Of course, temperature in the RV and door-open frequency can have a big effect on consumption rates.
Gary
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WILDEBILL308

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Re: How does a fridge work while I'm off-the-grid?
« Reply #20 on: November 05, 2017, 08:32:56 PM »
OK, I turned on the propane for the first time today. (I've been afraid I'd blow myself up:). So I turned it on, and lit the stove top to get the air out of the line (as someone suggested).  The stove worked great. But then the fridge wouldn't ever start. It tried. It kept clicking to try and start. The x would go on and off. Then I would try turning it off and on again. Maybe I'll try it again tomorrow and see how it goes.
Could still be some air in the  system. Lighting the stove helps get the bulk of the air out but you can still have a little in the lines to the refrigerator and hot water heater. Go ahead and try the hot water heater, it may take several tries with it to.
Life is better with hot water.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
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Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
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coxid

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Re: How does a fridge work while I'm off-the-grid?
« Reply #21 on: November 05, 2017, 10:51:24 PM »
We “dry” camp about 99.5% of the time. So our refer is on gas ALL the time, even when driving. Can’t remember when it was on 120 VAC last? A for driving with the refer on- Would you rather have Propane or Ptomaine?

AStravelers

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Re: How does a fridge work while I'm off-the-grid?
« Reply #22 on: November 06, 2017, 03:59:34 PM »
I doubt if they come that way from the factory, at least not intentionally, but the fridge icemaker is usually plugged to an inverter outlet so as to allow the icemaker to work off-grid.  Sometimes the fridge electric mode heater gets plugged into the inverter outlet, either accidentally or because the owner wants to avoid LP gas mode while traveling. That's fine as long as the engine alternator is running, but not so good once you park.
The reports I have been reading are that the MH is coming from the factory with the gas/elect fridge wired through the inverter. 

Here is a link to one of the reports:  http://www.rvnetwork.com/topic/129500-winnebago-mhs-have-gaselect-fridge-wired-to-inverter/

The other reports were in conversations on a Winnebago Yahoo Group.
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

WILDEBILL308

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Re: How does a fridge work while I'm off-the-grid?
« Reply #23 on: November 06, 2017, 07:04:44 PM »
I would like to see some verified proof not just hearsay. I bet some are confused because if the refrigerator has an icemaker it is plugged into the inverter circuit so it will function when on gas. I used this outlet when I installed my residential refrigerator.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

Mauleman

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Re: How does a fridge work while I'm off-the-grid?
« Reply #24 on: November 06, 2017, 09:55:55 PM »
so I too am waiting for you experts to explain the water heater... she needs hot water... actually so do I since this is my first MH and I pick it up from the previous owner on wed,,, I got the fridge down ... is the hot water heater automatic in that it switches to propane when no elect.. or is it strictly propane... 2008 La Palma.. 34...as overwhelming as some of this stuff seems at times it is kinda fun.. and we are really looking forward to rv'ing..

WILDEBILL308

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Re: How does a fridge work while I'm off-the-grid?
« Reply #25 on: November 06, 2017, 10:23:35 PM »
Lookin your owners manual or look up your model of water heater on line. Most likely it is just propane. (you need 12v power for the control board)  Make shure you have water in the system. Turn on your propane and light the stove to get the majority of air out of the system. you should be able to hear the igniter click when you turn the switch on. If it doesn't light you will need to cycle the switch off and back on. It might take a couple of tries to get any air out of that line.
Let me know if it lights. :))
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

Gary RV_Wizard

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Re: How does a fridge work while I'm off-the-grid?
« Reply #26 on: November 07, 2017, 11:07:49 AM »
Quote
is the hot water heater automatic in that it switches to propane when no elect.. or is it strictly propane... 2008 La Palma.. 34

The water heater does not auto-switch. There will be separate on/off switches for LP and electric modes, and you can use both at the same time if you wish (faster heating). Sometimes the electric switch is located in an entirely different place than the LP gas mode switch.

An upper tier rig like the La Palma will surely have a combo electric/propane water heater, but we can be more sure if you give the heater make & model.
Gary
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Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Tom

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Re: How does a fridge work while I'm off-the-grid?
« Reply #27 on: November 07, 2017, 12:20:10 PM »
In addition to a switch above the entry door for 110V operation of the water heater, our Monaco Camelot has an additional switch on the water heater itself. I suspect your LaPalma may have the same switch. Our switch was hidden beneath insulation around the tank.
Tom.  Need help? Click the Help button in the toolbar above.

Mauleman

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Re: How does a fridge work while I'm off-the-grid?
« Reply #28 on: November 08, 2017, 09:13:13 AM »
ok thanks guys... will find out all this stuff starting today... we pick it up later this morning... leaving San Diego for Temecula in about an hour... so the adventure begins... thanks for your help... i know I will need it more, "down the road" so to speak.... 8)

AStravelers

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Re: How does a fridge work while I'm off-the-grid?
« Reply #29 on: November 08, 2017, 03:20:25 PM »
I would like to see some verified proof not just hearsay. I bet some are confused because if the refrigerator has an icemaker it is plugged into the inverter circuit so it will function when on gas. I used this outlet when I installed my residential refrigerator.
Bill
Good point Bill.  Make me wonder if the reports I have seen of the fridge "cooling" AC power" going through the inverter are because the cords are switched between the ice maker AC plug and the fridge cooling AC plug.
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

 

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