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DaveK

How much LP gas does a RV frig use?

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I am a newbie/fulltimer trouble shooting a high LP gas consumption by my Dometic RM 3800 refrigerator. I am not sure if this is the right group, please advise if there is a better place to post my questions.

The frig runs a cold 5 to 10 degrees in the freezer constantly within 2 hours of start. This is true on electric or gas. The refrigerator compartment will cool to safe temp in 8 hours from start. When running on LP it seems to use 3 to 4 gallons per day and will empty our LP tank in 3 days. As a newbie this seems extremely high LP consumption! What is normal LP burn rate?

I am still determining if there is a LP leak adding or exclusive to the high burn rate. Still trouble shooting.

My main question, what is the rate of LP gas consumption I should expect from a Dometic RM3800.

Thank you in advance.

 

 

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I could not find any gas consumption information in the manual, maybe look at their troubleshooting ?? Hardware stores have spray on leak detectors, LOOK FOR LEAKS !!!!!!!!!!! Is the burner flame blue or yellow ????

Things that come to mind are proper gas pressure and gas regulator operation,,,,,,,,is the stove flame normal and short and blue and NOT  huge and yellow and likewise the fridge burner flame short and blue instead of yellow ???? IF IN DOUBT HAVE A TECH CHECK LP GAS AND REGULATOR AND PRESSURES INCLUDING THE FRIDGE BURNER ORFICE

 http://techsupport.pdxrvwholesale.com/wp-content/uploads/2019/01/Dometic-Refrigerator-Installation-and-Operating-Instructions-RM3800.pdf

Are you sure its NOT the hot water heater or furnace or stove/oven using that much LP Gas ??????? 

Do you have an LP Gas Detector?? If not I strongly advise you to get one.

What size LP Tank do you have 20 30 50 lb ????

If it empties a 30 lb in 3 days, THAT SEEMS EXCESSIVE if alls well and there's no leaks ??

I don't remember if I've owned a 3800, but I've never in 49 years of RV ownership had a gas fridge empty a tank (many had 30) in 3 days   

Sorry I cant give you the gas consumption rate maybe others have it ????????????? however that seems excessive so look for leaks and inspect the flame until someone can give you an accurate fridge gas consumption answer PLUS insure the water heater or furnace or stove/oven isn't a problem ???

John T

Edited by oldjohnt

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Welcome to the Escapee forums! This is a good place to post your question. 

I did some research online and find that a 10 cubic foot volume gas refrigerator will typically use about 1.5# of propane per day. A gallon of propane is 4.24# so that would mean that said refrigerator should take 13 days to use up a 20# bottle of propane. Most RV refrigerators range from about 4 cubic feet to as much as 12 cubic feet. Your propane must be going somewhere else as that is far more than any RV refrigerator that I know of. 

Edited by Kirk W
Edit to correct typo pointed out by podwkrz

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We boondock almost exclusively using propane for everything -- furnace, refrigerator, stove, water heating (we have an on-demand water heater).  Our propane container is 20# and we can go ~one month between refills if we're using the furnace...more time between fill ups if we're not.

Your propane consumption is way too much, particularly if all you are running is a refrigerator.  Now, if you are ALSO running a propane generator to operate AC, for example, then it might be a reasonable consumption.

I agree with others that something isn't right and you more than likely have a leak.  Personally, I wouldn't mess around with propane myself...I'd take the RV to someone qualified to work with propane.  

Edited by LindaH

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You have a leak somewhere.

First thing to check is, when the propane valve is on, but all appliances are OFF...smell around the underside, inside, and especially around the tank itself, the pigtail, and any joints, manifolds, and connectors or fittings.

If you smell ANY propane, turn off the tank. Come back in an hour or so, slowly open the valve, listen for gas entering the pigtail. Smell around everything again. If you smell propane again, you need to use a soapy spray and look for bubbles on every fitting and connection. Don't assume the fitting on the tank is leak-proof, check it too.

Even a brand new pigtail fitting can be leaky...I had a brand new one on a brand new trailer, that was leaking.

Check eveything.

 

 

Edited by podwerkz

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Thanks everyone for your quick replies.

I am suspecting a gas leak. Since we only occasionally smell a small wif of gas, I dismissed this as major.
The frig is always flashing the red light on gas, indicating it did not light even though it has a flame and cooling. I thought maybe the frig flame might be running non stop. I turned off the gas to frig and running 110 volt, I noticed the LP level drop but seems to be less. 
Note: All testing has been with stove, water heater and furnace turned off. Only frig used because we have food in there. So the last test was overnight, with frig running on 110volt. In less than 12 hours the tank dropped from 3/4 to between 1/2 & 3/4. I can hear gas flowing through the regulator when the valve is open and everything off.

We just finished spraying the gas line from the valve up to 4 entry points through the floor with soapy water, no bubbles. Sprayed external and internal connections, when accessible on each appliance, no bubbles. Never gas build up in the cabin and rarely smelled inside.

Everything seems to be pointing to an external link primarily. I just switched the frig to gas, the flame is blue. The weather seal on the lower left corner of the frig door does not seal tight, I suspect this will cause the frig to run more than normal.

I am thinking:

1) A small and elusive gas link on the underside.

2) Frig needs a new door seal.

3) Frig may also have another issue since the red light always blinks when on gas even though it is cooling.

Conclusion: Spray down the lines again to find the leak and get a new door seal for frig. Going through 14 gallons of LP every 3 days is expensive!

The door seals are close to $200! Does anyone know of a source I can magnetic door seal in bulk roll and make a new seal?

How much does an LP gas detector cost?

Thanks again, I appreciate all your help.

 

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3 hours ago, Kirk W said:

I did some research online and find that a 10 cubic foot volume gas refrigerator will typically use about 1.5# of propane per day. A gallon of propane is 4.24# so that would mean that said refrigerator should take 3 days to use up a 20# bottle of propane.

Correction: 20 pounds would yield about 13 days at that rate, not 3. 

But in reality, a 20# exchange tank is around 16 pounds of LP these days, and an average (and modern) RV fridge of about 4 cu ft could burn about one pound per day, in average conditions. This could yield around 2-3 weeks of use (depending on high or low ambient temps, opening and closing frequency, sun exposure on the fridge,  ventilation efficiency etc and assuming NO other appliance use) which lines up with my experience.

Edited by podwerkz

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3 hours ago, oldjohnt said:

I could not find any gas consumption information in the manual, maybe look at their troubleshooting ?? Hardware stores have spray on leak detectors, LOOK FOR LEAKS !!!!!!!!!!! Is the burner flame blue or yellow ????

Things that come to mind are proper gas pressure and gas regulator operation,,,,,,,,is the stove flame normal and short and blue and NOT  huge and yellow and likewise the fridge burner flame short and blue instead of yellow ???? IF IN DOUBT HAVE A TECH CHECK LP GAS AND REGULATOR AND PRESSURES INCLUDING THE FRIDGE BURNER ORFICE

 http://techsupport.pdxrvwholesale.com/wp-content/uploads/2019/01/Dometic-Refrigerator-Installation-and-Operating-Instructions-RM3800.pdf

Are you sure its NOT the hot water heater or furnace or stove/oven using that much LP Gas ??????? 

Do you have an LP Gas Detector?? If not I strongly advise you to get one.

What size LP Tank do you have 20 30 50 lb ????

If it empties a 30 lb in 3 days, THAT SEEMS EXCESSIVE if alls well and there's no leaks ??

I don't remember if I've owned a 3800, but I've never in 49 years of RV ownership had a gas fridge empty a tank (many had 30) in 3 days   

Sorry I cant give you the gas consumption rate maybe others have it ????????????? however that seems excessive so look for leaks and inspect the flame until someone can give you an accurate fridge gas consumption answer PLUS insure the water heater or furnace or stove/oven isn't a problem ???

John T

The tank is 68.5 lb.

Thanks for frig manual.

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I'm assuming that is a frame mount ASME tank and if you are not using the stove/oven more than a few brief times per day, (normal cooking) and (in the summer) you are not using the furnace at all, and assuming the tank is filled up, it should/could last for a couple of months of 'average' use....unless you have a leak.

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Dave, An RV Tech or even an LP Gas dealer can perform a pressure leak test in a heartbeat if you don't find anything yourself. Even if the fridge has a door seal leak I still don't envision using as much gas as you're talking about.

You're going to get this 

John T

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7 hours ago, DaveK said:

The tank is 68.5 lb

That should last 45 days for just the refrigerator. Do not ignore this as propane can be dangerous. It is heavier than air and is know to sometimes pool and any spark could set off an explosion. I am wondering if your leak might be in something like the water heater or furnace? Either one could be leaking and the gas venting to the outside and if your RV isn't in a building it would be easy for it to dissipate so that you don't notice it. I strongly advise you to keep the gas supply shut off except when testing for the leak. Run the fridge on 120V power. 

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Kinda sneaky, silently fixing the earlier numbers so that my quoted text and reply looks wrong.

Many other forums 'lock' the edit window after 15 minutes or so just for this reason.

Hopefully the OP will get this solved.

 

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10 hours ago, podwerkz said:

Kinda sneaky, silently fixing the earlier numbers so that my quoted text and reply looks wrong.

Really? The post states that it was edited, as all of them do when edited. The number was a typo and I repaired it because you caught it. I suppose I should have given you credit but didn't realize it mattered. 

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Mentioning that you have fixed an earlier typo that someone has quoted would seem to be sufficient...I would do (and have done) that.

But moving on, again. the important take-away here is that the OP knows to investigate the situation further, because they have a better idea of what we would consider 'normal' or 'average' refrigerator LP  consumption.

 

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First, download a copy of the service manual for your refrigerator from: http://bryantrv.com/docs.html

Read the nameplate on your refrigerator/appliance, it states the btu per hour for LP gas. The consumption rate may accurately be determined from the service manual, as the LP flame is constant, the flame size is determined by the cold setting.

This article by (now deceased) Gary Bunzer will help you understand how it works.

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Follow up.

I ordered a gas detector, found a leak underneath in a fitting to the furnace. Opened the flared copper fitting, cleaned and reseated twice. Leak is slower. Next step buy new copper tubing and replace run to furnace. May be crack in the copper tubing near fitting I can’t see.

I will continue to turn on gas only for stove and showers, as needed, until I get the parts to resolve issue. After the leak is resolved then determine if the fridg is using excess gas, which I am still suspecting is a lessor issue for high gas consumption.

Also replaced the regulator, it started sticking off after the original post. Someone previously installed a vertical 2 stage, I replaced with a horizontal 2 stage that is required for my configuration.

Thanks for each of your replies. The most helpful was the recommendation to buy a gas detector.

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Flare fittings should be assembled with some lube at the flare as when doing the final tightening, the flare may have the tendency to hold onto the brass fitting and wrinkle the copper flare, causing a small leak.  There are also gaskets for these flares, which will replace the lube.  With the vibration that RVs encounter, its a wonder that more leaks arent created.  Rolling earthquakes.

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