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Topic Boards => Coach => Topic started by: randall on December 31, 2008, 09:31 AM

Title: What is "burping" your refrigerator?
Post by: randall on December 31, 2008, 09:31 AM
Sent: 8/14/2005
My Dometic is dead.  I tried it on a/c and it gets hot around the heater box but does not cool.  The RV guy here said to "burp" it.  Has anyone had any luck with this?
randall in vegas
Title: Re: What is "burping" your refrigerator?
Post by: Oz on December 31, 2008, 09:31 AM
Sent: 8/14/2005
I have a Norcold which had sat in a rig, unused, for 5 years.  I started by hooking it up on electric and it did the exact same thing.  The first time I turned it over (burping).  I didn't hear a thing.  The second time, I thought I heard a trickle of ammonia in the tubing.  The third day, I definitely heard a trickle.  3 more days of turning it end-on-end and it was flowing freely.  Now, the freezer frosts within an hour of starting it and the main compartment is cold in about 3 hours.
I'm not sure exactly how it happens, but if the fridge sits for long periods of time, the ammonia must become dense from not being expanded by the heat and is like a clog in the tube.  "Burping" gets it flowing again. 
I also start the fridge 2 or 3 times during the winter to prevent this condition.  I sure don't want to have to remove the fridge and go through that again!
Title: Re: What is "burping" your refrigerator?
Post by: Oz on December 31, 2008, 09:34 AM
Sent: 8/14/2005
"Burping" is a method to free-up the ammonia which may thicken and clog in the tubing in the back of the fridge.  Ammonia is used in RV fridges like freon is used in home fridges.  Basically, when heated by the LP burner or electric element, the ammonia travels up the tubes and through the fins in your fridge causing it to cool.
When the ammonia clogs, your fridge won't cool.  To "burp" it, you take the fridge out and set it on its top for a day, turn it right-side up the next, and so on until you can hear the ammonia trickling up and down the tubing.  This may take several days, but it is necessary to free-up the ammonia.
Title: Re: What is "burping" your refrigerator?
Post by: randall on December 31, 2008, 09:37 AM
Sent: 8/24/2005
well it worked.  I pulled the fridge, turned it, turned it again, it made the burping noise.  plugged in the AC AND IT COOLED!!!!!!!!
wooooooo.  I haven't tried it on propane yet but what the heck.   thanks for the good advice all of you.c  old beer in my future
Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 09:38 AM
Sent: 12/27/2005
The fridge in our '87 Allegro hadn't worked in years.  Previous owners were told it needed "service"... read all the burping instructions and proceeded to try to remove the monster from its den.... but then.... My father has a friend who is RV fridge saavy... said the method to try prior to putting the effort into removing and burping it is to simply plug it in and let it run this can take anywhere from 3-10 days.... Our Dometic took 5 days but on AC power at least... voila, its back working.
Title: Re: What is "burping" your refrigerator?
Post by: moparmotivator on December 31, 2008, 09:40 AM
Sent: 1/1/2006
I had the same problem with my 73' vintage Dometic in a 270 Travco.
I pulled the monster out, no more then a 1/4 clearance getting it manipulated out of the kitchen and through the door.
I turned it upside down for a few days and then turned it back over and bypassed the ac thermostat and plugged it in till it was good and cold, about 6 hours.
I had to fix a few other problems before everything worked again though.
The contacts for the thermostat switch had to be cleaned to work at all on the ac side through the thermostat and the propane burner orifice had to be removed and cleaned out to cool properly on the lp side. 
Been a year since then and it still works great!!!
A little effort saved over $500 for a used replacement.
Good Luck
Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 09:42 AM
Sent: 5/8/2006
hi guys,

    Looks like we will indeed be burping our new baby.... 48+ to freeze and another 48 to a chilly reefer.... so...
    What are the steps to removing the beast? any hints will be greatly appreciated and I will take pictures and post the removal process as well.  Ours is a big beasty one of the 54x24x24s... not looking forward to it but wouldn't want to shoulder the $1k replacement cost either unless absolutely necessary...
   We did circumvent the problem partially. We have a Coleman 12V/110V cooler that we bungeed to the front cup holder (its an industrial strength oldie made from at least 1/2" plywood holds 4 cups!) . Served a dual purpose of keeping the corona's and limes chilled and kept the dogs from our laps while driving! it wasn't in the way one bit so maybe just replacing the Dometic with a cheaper apt model will serve ok for short trips anysay....

Title: Re: What is "burping" your refrigerator?
Post by: 1978Chieftain on December 31, 2008, 09:51 AM
Sent: 5/10/2006
Basically they are all about the same.  Removal is reverse of the install. Turn off gas/electrical (12VDC and 110VAC).  Disconnect gas/electrical.  Remove trim work if installed.  Remove any bracing/insulation stuff and unbolt feet from floor.  Pull out of opening into RV passageway.  Mule haul it out the door and burp (you can burp it in the rig if you want).  They are very very heavy.  Mandatory 2 big boy lift (maybe even 2 of the new Texas whoppers).   Caution and patience required.  Carefull of all piping as these things are filled with an ammonia based caustic gas.  Not only is the gas dangerous, if it leaks out the cooling coils are toast (approx $500 to replace if you do the work).  I am just saying be cautious when removing/handling.  You can test it out of the rig using the 110VAC connection as long as you do not have one that requires 12VDC power for a control board.  Gas can also be checked if you have the adaptors.
Burping:  rust particles and such (like hardened ammonia anti-caustic inhibiter) can clog up the pipes in the area of the boiler (heated portion) restricting or plugging up the flow of the gas.  Burping is an attempt to unclog those pipes so that the gas flows freely.  No promise that burping will work (didn't for me).  Some models are more susceptible to the problem than others.  Older style boiler was most susceptable.  Newer style is better but immune.   Running the reefer off level is bad juju.  The substance they add to the gas to prevent corrosion (ammonia is caustic) seperates from the gas and when boiled it hardens thereby plugging the pipe.  Burping will not fix that.
Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 09:54 AM
Thanks for the advice. At this point since it "don't work" attempting to burp it won't set us back any more than the manual labor to do it. I think I may have the manuals as the PO gave us a 3" stack of stuff I have yet to totally weed through.
Since it works partially... probably just partially blocked I'm thinkin' (then again I am blonde so that may be dangerous  !)
Now the decision if burping doesn't work... to replace with a standard apt. style or... another Dometic etc... We have the Coleman to plug into the dash while running and parked... Freezer would be nice if staying a while to make ice for the Rita's... hmmmm. Seems to be folks on this site 50/50 with that.
thanks Again
Title: Re: What is "burping" your refrigerator?
Post by: Lefty on December 31, 2008, 09:56 AM
Sent: 5/11/2006
A word of caution before you buy an apartment fridge. When we got our rig, the original 3-way fridge didn't work. After trying to burp it for a week without sucess, We decided to look into replacing it with an apartment style fridge. This has some good advantages, but a few drawbacks as well. First, the advantages; Cost, availablity, and larger size. Disadvantages; requires 110v power to run, may require modification to surrounding cabinentry to fit.
Because we rarely camped without 110v power hookups, we decided that wouldn't be a problem. we found a model at a "scratch & dent" sale, half off due to a large scrape on the side. Because we planned to flush mount it anyways, a scratch on the side didn't matter to us.
We overlooked a very important thing!! And it caused our rig to catch fire! We neglected to read the power requirements label before we installed it. Turns out, it required only 5 amps to run, but 18 amps to start the compressor! Our rig was on a 30 amp hook-up, and the roof AC requires 15 amps to kick on the compressor. Add in a TV, clock, coffee pot, and a few more "goodies", and when the fridge tried to kick on, it overloaded our plug. For some reason, it failed to trip any breakers, neither in the rig, or at the campgrounds plug. We awoke at 2:am to a warm interior, and no power. We noticed a flickering outside, and when we looked out the window, we saw the campground power box blazing merrily!! Thank God it caught fire at the box, and not in the coach!
After quietly moving to another campsite at the other end of the campground (we had arrived after the office had closed, so they never knew we had been parked there-lol)
and a trip to the all-nite Walmart for a replacement end, I was able to get the juice back on. But from then on, we had to run a seperate cord for just the fridge. Most campgrounds have a 30 amp connection, and a 20 amp connection (a regular dual prong grounded outlet). We plug the main cord into the 30 amp, and the extension cord for the fridge into the 20 amp. Had I not had a very heavy gauge extension cord (rated for 50 amps), this would not be possible.
  We later found similar sized models, that required much less power to operate. Some were as low as 1.5 amps running, 4.0 amps starting These would work just fine using the existing plug in the RV.
Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 09:58 AM
Sent: 6/17/2006
ok, reefer is out! yea... ok its out of its space and sitting on its head but.... it doesn't  fit out the door.... knew it was too good to be true. Haven't tried the drivers side door yet (or measured it to see if it would...). anyway It gurlgled well when flipped, but we will keep flipping. Pat did find that the control knobs didn't really have good contacts... so we'll give it a couple days and plug er in...

Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 09:59 AM
Sent: 6/20/2006
How many flips? its gurgling nicely. So far 24 hours on its head, side, and other side. Figure back upright tomorrow then plug it in and see..... Its been an exercise (sweat, sweat, sweat).... to flip it without scratching any trim, paneling, floor cover, and/or ripping upholstery, BTW.... the couch/bed os bungeed backwards.
Whoever installed it even put some silicone on the sides too..... oiy.  So hopefully it will work now... if not... its an RM 2800. found a RM2600 on ebay for $875 (used retooled  cooling 3 yr warranty), and one at RV place in Lancaster PA (about 3 hrs drive to pick up)... for $1165... and one at $1600 at the "Dometic" dealer for our area in Baltimore plus $150 install... (i'm that this will go exponentially up as a window may have to be taken out to get old out and new in....
ok off to mix a salad for dinner......
Title: Re: What is "burping" your refrigerator?
Post by: Oz on December 31, 2008, 10:01 AM
Sent: 6/21/2006
If you've noticed that the "gurgling" of the ammonia has gotten louder, indicating that it is flowing more freely, then you may have solved the issue.  A good "burp" can take a few days of flipping... did it myself several days with the Norcold which sat for 5 years.  I didn't think it was ever going to free up... but it did, and cools exceptionally well now.  Let's hope, yes?
Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 10:02 AM
Sent: 6/23/2006
Tomorrow is the day of truth.... Been a week of flipping every 24... so far only 2 dings in the wallpaper.... oops. Let you know.... All I know from the PO is that "it never worked"... they owned it about 4 years near as I can tell. Prior to that it sat but don't know how long... It does have 67K on the engine so the first owner did lots with it prior to parking her due to his old age.
Hey did y'all know that Cedar Point is just a hop from the Jam? they even have critter sitting and Campers Village! wohoo.... think we will head out sunday to there. Monday if you listen well you'll hear me screaming getting my ya-ya's out on all da coasters... wohoo!!!! I solid day of screaming, getting battered and bruised but.....ahhhhhh.

Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 10:03 AM
Sent: 6/27/2006
well... nada... been plugged in for 3 days now and ain't one little bit cold... ah well. looks I'm gonna start surfing for a new fridge as soon as the flood waters recede.... over 6" of rain so far... oiy.
Title: Re: What is "burping" your refrigerator?
Post by: tiinytina on December 31, 2008, 10:04 AM
Sent: 6/28/2006
Well, Big Discount RV has a charge on my Visa for $1174 for a replacement Dometic RM 2852 (the new version of the 2800)... Free Shipping to commercial addresses so its coming to my Job #2 site that has a loading dock..... Best price I found anywhere and beat most prices by minimum $300... Yea!... Now to figure out how to get the old one out and the new one in as the regular door is not big enough.... Still haven't measured the driver's side door yet.... The Exit rear Window... however may be used
Title: Re: What is "burping" your refrigerator?
Post by: tatkin on December 31, 2008, 10:06 AM
Sent: 6/28/2006
So if the frig is cooling when running off 110 then that means it does not have to be burped ?    I have never lit my frig up with the LP yet and I was under the impression that it used a different method to cool when using the LP ...
Title: Re: What is "burping" your refrigerator?
Post by: OldEdBrady on December 31, 2008, 10:09 AM
Sent: 6/28/2006
Whoa!  It doesn't matter HOW you run it.  The mechanism that actually runs it is exactly the same.  12V, 110V, propane--it's still operating from the same mechanism.  It's only the "juice" that runs it that changes.
Title: Re: What is "burping" your refrigerator?
Post by: ClydesdaleKevin on December 31, 2008, 10:11 AM
Sent: 7/1/2006
My main entrance is the same size as yours...and the new fridge fits...barely. 
When bringing it into the rig, you have to turn it sideways...the depth of any RV fridge is DESIGNED to be just slightly narrower than our standard door WILL fit...barely...
Don't worry, WILL fit...sideways (door in your right hand, cooling fins in your left, or vice versa).
Title: Re: What is "burping" your refrigerator?
Post by: DanD2Soon on December 31, 2008, 10:12 AM
Sent: 7/1/2006

It Will fit! - - Somehow - - we had to remove the door (easy) & take it in like Kev said;  Sideways.   Most of those door are made to come off and.or switch which side the hinges swing from - Not to worry - there is a way.
You're right about the absorbtion frig - if it's working well on any source, the problem should not be burping.  A three way (LP/12VDC/110VAC) frig uses the same ammonia system for all three sources - but each source uses a different "Heater" to evaporate the ammonia in the first place.  For LP its actually a flame operating in the "chimney coil", and for 12VDC and 110VAC each source has its own heater element mounted near or within the same chimney.
Title: Re: What is "burping" your refrigerator?
Post by: RedneckExpress on September 19, 2011, 07:27 PM
In Ammonia Absorption Fridges, what causes blockages is not the ammonia itself, but the salts that are part of the chemical mix in the pipes, your average RV Fridge has a mix of Ammonia, Water, Salts, and a Rust Inhibitor that circulate through the pipes in the back. 

Sometimes when a unit sits for too long (Even Level) The salts will start to crystalize and create blockages.  What happens when you "Burp" the fridge is you reverse the flow of the solution through the pipe, helping to break up and redisolve the salts.   This method is hit or miss, depending on how bad the blockage is. 

When a fridge is run out level, what causes it to stop working is that the unlevel position allows for all of the water to be evaporated off, leaving the salts behind in a hardened crystalized form that will not redisolve no matter how many times its burped. 

Title: Re: What is "burping" your refrigerator?
Post by: Oz on September 19, 2011, 09:56 PM
That's very good info!  And yes, it's definitely hit or miss but, it's worth a try before taking the shot in the wallet for a replacement.  Good lawd they're expensive!  I had to work mine over and over for 3 days before it fully cleared.  (It had sat, unused and unmoved for 5 years.)  The first day, I didn't think it was going to happen but then, I heard a slight trickle.  Each time I turned it, I heard it louder.  Once it was flowing good and I put in my rig, I got 5 years of excellent service from it until I sold the RV.
Title: Re: What is "burping" your refrigerator?
Post by: RedneckExpress on September 20, 2011, 11:31 AM
Yeah, I'm not looking forward to the day when my G.E 2-way finally gives up the ghost.  3 more years and it'll be 40 years old, I got lucky in that regard, as it has been keeping good and cold ever since I made some mods to it. 

When she does finally go, I'll likely take her apart and send the cooling unit in to be rebuilt.  The one major draw back to newer units is that they no longer galvanize the cooling pipes, something the early Swedish made units had, which was why if they were taken care of, 40 years later, they're still running. 

Another interesting tid bit is, keeping the fridge running vs turning it on and off will actually extend the life of the unit as it keeps that rust inhibitor flowing, which in turn keeps the cooling unit from rusting out from age. 
Title: Re: What is "burping" your refrigerator?
Post by: JDxeper on January 20, 2012, 08:28 PM
I found this at

A gas refrigerator uses ammonia as the coolant, and it uses water, ammonia and hydrogen gas to create a continuous cycle for the ammonia. The refrigerator has five main parts:

Generator - generates ammonia gas
Separator - separates ammonia gas from water
Condenser - where hot ammonia gas is cooled and condensed to create liquid ammonia
Evaporator - where liquid ammonia evaporates to create cold temperatures inside the refrigerator
Absorber - absorbs the ammonia gas in water
The cycle works like this:
Heat is applied to the generator. The heat comes from burning something like gas, propane or kerosene.
In the generator is a solution of ammonia and water. The heat raises the temperature of the solution to the boiling point of the ammonia.
The boiling solution flows to the separator. In the separator, the water separates from the ammonia gas.
The ammonia gas flows upward to the condenser. The condenser is composed of metal coils and fins that allow the ammonia gas to dissipate its heat and condense into a liquid.
The liquid ammonia makes its way to the evaporator, where it mixes with hydrogen gas and evaporates, producing cold temperatures inside the refrigerator.
The ammonia and hydrogen gases flow to the absorber. Here, the water that has collected in the separator is mixed with the ammonia and hydrogen gases.
The ammonia forms a solution with the water and releases the hydrogen gas, which flows back to the evaporator. The ammonia-and-water solution flows toward the generator to repeat the cycle.

I am very interested in this and may have to try it myself, as i have an old rv refrigerator jut laying around. I dont think the heat tape will work(not nearly hot enough), but it would be very easy to use a lantern base burning lamp oil or low odor mineral spirits. Very cheap and effective.
Title: Re: What is "burping" your refrigerator?
Post by: Oz on January 20, 2012, 08:41 PM
Would be great if this works.  It should take a lot less time than burping!
Title: Re: What is "burping" your refrigerator?
Post by: OldEdBrady on January 20, 2012, 09:21 PM
A lot of people don't have the option I do.  But, with the trailer right here in my yard, I simply plug in the trailer power, and keep the fridge going on 120V.  Never had a problem, even if it is a  1976 model.  It seems (from what I've read) the basic problem is "downtime" for the fridges.  If they aren't running a lot, they tend to have problems.  I could be wrong, but I'm just basing that one various threads I've read.
Title: Re: What is "burping" your refrigerator?
Post by: ClydesdaleKevin on January 21, 2012, 12:02 PM
You are right, Ed.  Keeping your fridge plugged in is the best thing you can do for it for longevity. 

There are 2 enemies of RV fridges...sitting around, allowing them to clog up over time, and rust eventually eating up your coils causing the gas to leak out and killing the fridge.

By keeping it always plugged in or running off propane, not only will it never clog up, the heated coils are much less susceptible to rusting out.  Since there aren't any real moving parts on these fridges, they won't wear out...and even if you do get electrical wear resulting in bad circuit boards or switches, those parts are WAY cheaper to fix or replace than replacing the cooling coils...or even the whole fridge.

Title: Re: What is "burping" your refrigerator?
Post by: RedneckExpress on January 23, 2012, 01:00 PM
The one thing they don't include in that ingredient list is the salts that are also in the solution, which is what causes blockages, and the rust inhibitor that keeps the water from rusting out the steel pipes. 

Fridges, especially older units, will last a long time so long as they are run level and run to keep that rust inhibitor flowing through the pipes. 
Title: Re: What is "burping" your refrigerator?
Post by: ClassCKing on January 24, 2012, 10:40 PM
im gonna say and ask this..i had to burp my fridge,took 3days of turning side to side  and over and over.had nothing .than a neighbor mentioned that he had the same problem with his.he said that he took a hand held propane torch put it on low and put it in the flute area and left it there for about 15 to 20 min flipped it a couple of times and it worked..well i tried it and it worked for me and i havent had a problem JDxeper mentioned heat tape a page or so question is never heard heat tape used does it work?and if it did..livn in a colder climate like i do it would keep the coils warmer longer after there was no power..i like the idea for boondockn...just a thought  Hm?
Title: Re: What is "burping" your refrigerator?
Post by: Oz on January 25, 2012, 10:02 PM
by ClassCKing:  JDxeper mentioned heat tape a page or so question is never heard heat tape used does it work?

Heat tape is most known for its use with mobile homes.  Since the plumbing runs under the floor and is exposed to cold weather, the "tape" is basically wires, encased in a strip, which warm-up and is wound around plumbing pipes and plugged into the house electric, thus preventing the pipes from freezing.  Note that, for many years, most mobile home fires were the result of heat tape because it wasn't checked on a regular, frequent basis for signs of damage from rodents and any areas where the casing may be wearing through.
Title: Re: What is "burping" your refrigerator?
Post by: ClassCKing on January 25, 2012, 10:22 PM
good point there Mark D:oH! that you mentioned it your right :)rotflmao i could see the tape but not the wires...brain fart
Title: Re: What is "burping" your refrigerator?
Post by: cattlejack on September 26, 2020, 08:07 AM
I just bought  what I think to be in good shape, 1972 Indian, but I don't know anything about her history, the PO said that the Norcold refrigerator was a newer model.  I went to start it up, it seems to be running but never got cold.
PO said she had been in storage for a long time. I don't know anything about Rving, so everything has a learning curve. To burp this unit, after I figure out how it going to come out, is there anything I have to unplug, disconnect or remove first?
Thanks, everyone for your help, after this it's the furnace, water heater, air conditioning, etc, etc. 
Title: Re: What is "burping" your refrigerator?
Post by: Oz on September 27, 2020, 08:12 PM
Nothing to unplug once you have it out.
Turn it upside down and leave it for a few hours.   If it isn't bad, you should hear the ammonia trickling pretty quickly.  If it is, you may have to do this 2 or 3 times.
Title: Re: What is "burping" your refrigerator?
Post by: Woodybago on September 29, 2020, 07:37 PM
My 74 Brave had a similar problem. We burped it, but that did not work, so we had an expert recharge the unit and refurbish it. It is a Dometic 4 cubic footer. However, it still did not get really cold. One of the owners of Sand's RV in Madison, Ohio suggested that we change the gas regulator at the propane tanks. He said old ones lose the ability to push the gas through enough to get the frig cold. After following his advise our frig runs like a new one.
Title: Re: What is "burping" your refrigerator?
Post by: Oz on September 29, 2020, 07:55 PM
Yep. That can certainly be a problem as well.