Gas Absorbtion Refrigerators

[Lisa H.]

Does anyone know anything about gas absorption refrigerators. I need to replace the little Hadco frig. in the campster and the conversion charts indicate that the Norcold N300.3 is the only replacement of the same size. The N300 model is not a 3-way, which I need due to the primitive camping areas I frequent. Does anyone know if this is a reliable refrigerator? Do I have any other options that I am unaware of if I want a 3-way? I want to get a frig. and install it before the end of June and may need to factor in shipping delays.

The Thetford website has a PDF diagram of how this kind of refrigerator works but it has no meaning to me. http://www.thetford.com/Portals/0/PDFs/N26...ptionSystem.pdf
I just need to know whether or not they are energy efficient and reliable. Any advice is greatly appreciated as this purchase will be a big chunk of my trailer renovation budget!

[danny m]

Does anyone know anything about gas absorption refrigerators. I need to replace the little Hadco frig. in the campster

All RV refrigerators are absorption cycle regardless where the heat comes from. They should never wear out as they don't have any moving parts, so I would suppose any brand is reliable. Dometic (formerly Servel) is the most common and cheaper than Norcold as I recall. Here's a chart for Dometics (get out your glasses!).

Dometic chart

As for efficiency they would all be about the same. A home sized Dometic (8 cu ft) burns about 2 gallon per week so a little RV sized one would go a long way on a 20# propane tank.

EDIT: By the way, what's the problem with the old unit?

[pjanits]

These thing work by magic mostly.
Sometimes the stuff inside separates or something and you can turn them upside down for a day or two and it's all happy again.

What happened to the one I had in my old 28' trailer was where the condensation happened the most, the steel pipe rusted thru and the magic ( Ammonia) leaked out.
Pretty overcoming the first time I opened the door. Then the ammonia ate away at some aluminum sensor.
Anyway short story is I took it to Elkhart ,Ind and a guy rebuilt it for a third of what a new one would cost. It seems that what happened to mine is common.

[danny m]

What happened to the one I had in my old 28' trailer was where the condensation happened the most, the steel pipe rusted thru and the magic ( Ammonia) leaked out.

Did this pipe rust from the outside in?

I have some old home sized Servels in the basement dating from the forties. They still work. I thought nothing could go wrong with one of these other than a thermocouple going bad.

[Lisa H.]

Dometic chart

As for efficiency they would all be about the same. A home sized Dometic (8 cu ft) burns about 2 gallon per week so a little RV sized one would go a long way on a 20# propane tank.

EDIT: By the way, what's the problem with the old unit?

Thanks for the Dometic chart! FYI, if you click on the chart the teeny tiny print gets magnified. Yeah!

The old Hadco is only 110v. Before I drove 6 hours to check out the trailer before buying it I was told that "the refrigerator is useless because it is only 110v." After I arrived I was then told it didn't work. In all honesty I have not bothered to try to turn it on because it was missing the cap on the roof vent and there is evidence that snow melted into the compartment. I don't want to risk a short when I'll never be able to use this kind of frig. even if it does work. I really need a 3-way frig. I wonder if Traveland will take it in trade and refurbish it?

[Harry Young]

Thanks for the Dometic chart! FYI, if you click on the chart the teeny tiny print gets magnified. Yeah!

The old Hadco is only 110v. Before I drove 6 hours to check out the trailer before buying it I was told that "the refrigerator is useless because it is only 110v." After I arrived I was then told it didn't work. In all honesty I have not bothered to try to turn it on because it was missing the cap on the roof vent and there is evidence that snow melted into the compartment. I don't want to risk a short when I'll never be able to use this kind of frig. even if it does work. I really need a 3-way frig. I wonder if Traveland will take it in trade and refurbish it?

There is a company in Washington State that will refurbish your unit, if the cabinet is in good shape I would...The refrigeration section is removable, when you contact the company they will explain shipping, in rebuilding the unit they make a few modifications so it runs better...I am in refrigeration and understand these systems...On the Norcold question...These units are good...They are not as fussy about being level as the Dometics...All are going to the newer design...The biggest problem is when they are operated not level and are of the old design. The ammonia inside is stabilized from corroding the metal tubes inside the unit with another chemical that makes it less corrosive to the contacted components, when not run in a level condition the chemical components separate when they boil...These chemicals separate and the whole well balanced shooting match craps out...Once the chemical solution is changed there is generally no going back... So leveling is of supreme importance...Pulling it out and tipping it up side down can provide short term relief, However it does not make the balance of caustic ammonia and the buffered agent (puts them back in solution with each other) work again... Ergo the caustic ammonia starts to react with the metal tubes until pin hole leaks develop. Special equipment is needed in the repair process, it must be done in an oxygen free environment so there are few companies that attempt repair locally...almost all service centers will ship your refrigeration section they take out and mark up the cost when it returns rebuilt and reinstall it charging you allot more...You can do this yourself fairly easily...I hope this helps, if you need more I will be happy to give you the business names and web addresses of the people you can deal with. I have replied in a generalized way respecting you may not be in the business...The process and the chemicals involved are more detailed and dangerous than I have explained, I in no way recommend anyone service the refrigeration system...

The controls and systems not related to the sealed amonia refrigeration tubes are another matter and are simple.

Harry

[danny m]

The old Hadco is only 110v. Before I drove 6 hours to check out the trailer before buying it I was told that "the refrigerator is useless because it is only 110v." After I arrived I was then told it didn't work. In all honesty I have not bothered to try to turn it on because it was missing the cap on the roof vent and there is evidence that snow melted into the compartment. I don't want to risk a short when I'll never be able to use this kind of frig. even if it does work. I really need a 3-way frig. I wonder if Traveland will take it in trade and refurbish it?

If twelve volt operattion isn't too important and you're mostly interested in propane operation you can still see if the system works on 120 volts. If everything is dry inside you needn't worry about a short. If the refrigerator gets cold on 120 volts then the problem the previous owner had with propane is probably simple to fix. It may just need a new thermocouple or something else cheap.

[Lisa H.]

If twelve volt operattion isn't too important and you're mostly interested in propane operation you can still see if the system works on 120 volts. If everything is dry inside you needn't worry about a short. If the refrigerator gets cold on 120 volts then the problem the previous owner had with propane is probably simple to fix. It may just need a new thermocouple or something else cheap.

The Hadco 300 refrigerator is only 110v and does not have propane nor 12v capability. I'm confused. Are you suggesting that it could potentially be converted to operate on a battery and propane? Do you know if some of these repair companies will take an old refrigerator in (like an old car trade in) and use it's nominal worth toward the purchase of a new refrigerator? If this old Hadco cannot be made into a 3-way then I want to get rid of it and buy another unit that meets my needs. I will mostly be powering the frig. with an 85w solar panel and battery or propane. In all honesty, I don't see myself camping very often in places with full hookups. . . there are too many people and that's exactly what I am trying to escape by going to primitive campgrounds off the beaten path. Perhaps if I go camping locally at the San Mateo campground during the summer I'll use the hookups there and will need 110v. But other than that, I can't imagine myself sticking with this frig. with it's current limitations even if it does work satisfactorilly on 110v.

[danny m]

The Hadco 300 refrigerator is only 110v and does not have propane nor 12v capability. I'm confused. Are you suggesting that it could potentially be converted to operate on a battery and propane?

I'm not familiar with Hadco refrigerators. I thought it was a two way, propane and 120v, and the propane didn't work. Well if it's 120/110 volts only, then you would want to go with a new one. I suppose you could get a little for the old one at an RV salvage dealer.

[Harry Young]

First I am sorry I am confusing you...According to my books your model 300 is not a compressor operated refrigeration system, it is an ammonia absorbtion system powered by a 300 watt (aprox) 110 volt a/c (elec) heater, this heater is what begins the chemical process that turns into refrigeration... below is a snapshot of my book.<span style="font-size:10pt;line-height:100%"><div align="left">HADCO DOMETIC</div>
<div align="left">HR-2 same as RM 24</div>
<div align="left">HR-3 same as RM 36C</div>
<div align="left">HR.4 same as RM 460</div>
<div align="left">HR-6 same as RM 660</div>
HR-7 same as RM 760

</span>Yours would be the three...There are three manufactures who make the products that has the Hadco name on it in their refrigeration family line...If my book is correct you can simply replace the 110v heater with a 12v and yes it would be a 12v, if the refrigeration module were sent in to be refurbished you can ask for a 12v/propane module back intead of an electric only, (12v/110v) But you would have to beg borrow or steal the rest of the hardware you would need (pilot assembly, ignitor ect) and that would be painfully tedious...To answer honestly... this is more than you probably want to do after you factor in all the "stuff" and the different bottom chasis these units came with when gas equiped.

If your unit is compressor driven then in the back there is a round black can looking thing about the size of a grapefruit...this means your unit is made by the other two guys Hadco uses...The black can will say embrako or danfoss according to my books or a stamp "made in Italy"

Since the topic in the forum header was listed as "absorbtion system" I approached the subject from that point of view...In hindsight I should have asked the S/N and then asked the millon dollar question about if this was a compressor driven 115v or an absorbtion 115v from the start like a good technician.

I got one of these to work on from a guy who had a Serro Scotty for a member of Tin Can Tourists in Az. and he wanted to stay exactly O.E.M. so I did regardless the cost and it was converted to gas/elec...If its not important to you to keep this exact fridge because it came with your camper then I would go the Norcold suggested earlier and your thinking much better than I am.

Even if yours is the 110v absorbtion unit and you put in the 12v heater the 12v amp draw would draw down the best deep cycle battery in about 6 hours...so the advantage of converting to 12v from 110v is minimal without gas to be the primary energy source when stoped and camping...I would not want a fridge that makes my battery go dead that fast...You really want the 12v/Propane refrigerator.

Again for the confusion I apologize to all...

P.S. Be sure of the disposal rules for your refrigerator in your area according to its type...Freon or if its Amonia... It can very flamable, caustic and poisonous, Never puncture or incinerate this type of system, respritory distress or failure can result.

Harry

The Hadco 300 refrigerator is only 110v and does not have propane nor 12v capability. I'm confused. Are you suggesting that it could potentially be converted to operate on a battery and propane? Do you know if some of these repair companies will take an old refrigerator in (like an old car trade in) and use it's nominal worth toward the purchase of a new refrigerator? If this old Hadco cannot be made into a 3-way then I want to get rid of it and buy another unit that meets my needs. I will mostly be powering the frig. with an 85w solar panel and battery or propane. In all honesty, I don't see myself camping very often in places with full hookups. . . there are too many people and that's exactly what I am trying to escape by going to primitive campgrounds off the beaten path. Perhaps if I go camping locally at the San Mateo campground during the summer I'll use the hookups there and will need 110v. But other than that, I can't imagine myself sticking with this frig. with it's current limitations even if it does work satisfactorilly on 110v.

[Harry Young]

To the campster/compact owners:

I felt so bad about confusing rather than helping I forgot to say I had replaced my refrigerator in my Astro, (its a carbon copy of the campster in most ways). I did remove the drawer under the old refrigerator in order to make the room for a standard size dometic, I added the top vent to the roof so the heat from the unit can excape and installed a service door on the outside of the camper to access the pilot assembly...It looks really nice I think...The issues I faced that I did not foresee going into this renovation was that the body of the camper tapers from the middle seam/lip both to the roof and down to the bottom of the trailer...All refrigerators are built along the idea of square cabnets in all 3 dimensions...a tapered space gets to be a problem for the rear condenser fins of the fridge...The depth of the unit I found is far more critical in the end than the length or width wilst measureing for the origional hole which is where my attention to details was at the time...Measure from the top of the rectangular space inside the camper to the outside wall and then do it again at the bottom from the interior wall to the exterior wall of the camper. (measure front to back) ((I found some units to deep)) I can send detailed pictures of my camper if it helps.

As a precaution I lined the interior wall around the refrigerator with a flame proof fiber glass foil backed 1/2" auto firewall mat, I included covering the wood at the bulk head and the fiberglass exterior skin...Since the rear of these units are open to the weather thru their louvers and exhaust vents it was important to me to insulate this area, and it provides some protection from open flames in case of a malfunctions with combustable materials.

I had to negotiate the wheel well when installing the access door...and after removing the drawer for an extra sized and more common size refrigerator I used the wheel well top inside the camper as a good platform anchor point for the base of the unit...I did this because my refrigerator is a good size one and they are heavy units.

I have found good units thru craigslist, also I hunt rv wrecking yards rather than lay out awful sums of money for 3 way refrigerators you can save alot this way.

Harry

All RV refrigerators are absorption cycle regardless where the heat comes from. They should never wear out as they don't have any moving parts, so I would suppose any brand is reliable. Dometic (formerly Servel) is the most common and cheaper than Norcold as I recall. Here's a chart for Dometics (get out your glasses!).

Dometic chart

As for efficiency they would all be about the same. A home sized Dometic (8 cu ft) burns about 2 gallon per week so a little RV sized one would go a long way on a 20# propane tank.

EDIT: By the way, what's the problem with the old unit?

[Casandra F]

Harry, you da MAN.

I don't even OWN an egg yet, but when I do... and if that egg needs some kinda fridge work... and I don't know what to do... boy, I'm gonna be on you like flies on poop. You're the wikipedia of rv fridges. Good luck Lisa.

[pjanits]

Yes it rusted from the outside in. On mine, a larger Dometic I beleive the guy showed me the spot.
It's about 1/3 down from the top and in the middle of the coil. Right where the plastic drain area is.
This was about 25 yrs ago so I'm hazy on the rest of it. I remember the shop had a ton of the same type frig being fixed. Pretty much for the same reason.

Now my friend removed his about the same time and put a larger one in his trailer. The original he stuck into his basement wall , plugged it into 110v and it's still running today.

[Roger H]

A point of order for those less experienced with RV refrigerators:

The three way refrigerators are 12v DC, LP, and 120v AC. LP is for use when camping "off the grid". 120v is used, of course, when on shore power. The 12v DC system is only for use when the trailer is moving; it's not a alternative "boondocking" power source to LP. The heating element draws enough amps that is will run both your trailer and tow vehicle batteries down in a short time, usually less than three hours or so. Your tow vehicle alternator supplies enough current to make it work fine though. Many RV refrigerators are now just 120/LP, and if you pre-cool the fridge before you move the trailer, it'll do fine for all-day traveling without being plugged in or having the LP running.

Roger

[danny m]

Yes it rusted from the outside in. On mine, a larger Dometic I beleive the guy showed me the spot.
It's about 1/3 down from the top and in the middle of the coil. Right where the plastic drain area is.
This was about 25 yrs ago so I'm hazy on the rest of it. I remember the shop had a ton of the same type frig being fixed. Pretty much for the same reason.

Now my friend removed his about the same time and put a larger one in his trailer. The original he stuck into his basement wall , plugged it into 110v and it's still running today.

Something Harry Young said here,

P.S. Be sure of the disposal rules for your refrigerator in your area according to its type...Freon or if its Amonia... [b]It can very flamable, caustic and poisonous, Never puncture or incinerate this type of system, respritory distress or failure can result.

reminded me of something. Absorption cycle refrigerators have another gas besides ammonia in them, which I think is hydrogen (correct me if I'm wrong). This is the gas into which the liquified ammonia evaporates, just as water evaporates into air at a temperature far below its boiling point. If you smell ammonia then you may also have a hydrogen leak with the possibility of an explosion hazard. Of course if you smell ammonia you should get out anyway as it is poisonous in high concentrations.

[Harry Young]

You are bang on Danny and Roger,

At the risk of repeating myself both your talking points are 100% correct.

The difference in the properties of these gases and condensed liquids which boil at a low temp creates the heat pumping qualities and are very explosive...Hydrogen is one of the bad boys in the recipe.

When the refrigerator is not level a death cycle begins corrupting its well thought out design making its advantages become its undoing...The buffering agent in suspension inside the box is in solution ie. "a soup" this buffering agent gets left behind as a condensed solid in the tubes and does not easily go back into solution because it crystallizes...These crystals may clog the carburetor "the funny tube that is always to one side and vertical to the heat source ie a 12v heater or 120v heating element or a pilot flame source.

This became so annoying in the old design that new units now use a dual carb set up on all manufactures now...The old ones could be salvaged in the short term with the upside down trick but it has a cruel catch...It will get you camping again...but...Even though the carb would/could unplug the buffering agent that made the ammonia behave does not redisolve into the now more corrosive ammonia solution...The crystals migrate to the bottom of the system and sit there inert sometimes trapped by a screen in some models...The ammonia now has become more caustic and more corrosive albeit more dangerous! It begins to attack the metal tubing from the inside out until pin holes develop...Allot of fires occur in older RVs because when these leaks occur while traveling and on propane...usually because the 12v element burned out and the owner could not find a replacement...the leak causes a rapid fire to develop, its several times hotter than a campfire or propane and can have a shockwave faster than sound.

Which brings me to the other correct point this forum makes... You guys are correct about traveling... if in the desert or in urgent need use 12v mode only when on the move...Or dry ice, Or if your like me a gallon plastic bottle of really good frozen water frozen two days before...Or a gallon of frozen milk...Store it in the pre cooled box while on the road...Start your unit up at your camp spot after leveling all three axis points for the box!...level respective to the fridge not the coach!!!!! this is critical Manufactures are sinners campers...When they install these fridges they oft just throw them in by eyeball...When you level the coach the refrigerator can be perilously off canter even though the coach is honestly saying level. But the refrigerator is as crooked as bad dice in a cheap vegas casino.

These boxes last years and years...more than the modern freon ones...no moving parts really... when used correctly they last and last. I have a full sized one "looks just like a home unit" in a cabin that is 30 years old, never serviced.

Ignorance kills these and makes me money.

Harry

[Lisa H.]

These boxes last years and years...more than the modern freon ones...no moving parts really... when used correctly they last and last. I have a full sized one "looks just like a home unit" in a cabin that is 30 years old, never serviced.

Ignorance kills these and makes me money.

Harry

Harry, you got me thinking that if my current HADCO still runs on household current it might be worth using in my garage. Are they relatively energy efficient or do they use a lot of electricity? It sure would be nice to have access to cold soda and juice while I'm working down in the garage restoring the Campster!

Thanks for all of your helpful, informative advice!
Lisa

[Harry Young]

It uses aprox 300 to 400 watts per hour, a compressor in this size range uses 600 to 800 watts...if it works Id use it.

Harry

Harry, you got me thinking that if my current HADCO still runs on household current it might be worth using in my garage. Are they relatively energy efficient or do they use a lot of electricity? It sure would be nice to have access to cold soda and juice while I'm working down in the garage restoring the Campster!

Thanks for all of your helpful, informative advice!
Lisa

[Lisa H.]

It uses aprox 300 to 400 watts per hour, a compressor in this size range uses 600 to 800 watts...if it works Id use it.

Harry

Let's cross our fingers I can actually get the thing going! We'll find the answer this weekend.

Thanks again!
Lisa

[Rob Carmody]

I thought I'd jump onto this thread instead of starting a new one.

We have a 1982 13' Burro with just an ice box. I really want to take that out and add a fridge. What are my options? I've only found 2 models that I believe would work and 2 that are deaper and not sure if they will work:

Dometic:

RM 2193 Americana - I know this one will fit
http://www.dometic.com/enus/Americas/USA/RV-Products/refrigerators/Refrigerator-Product-Display/?productdataid=71045

DM 4223 Americana - This one is a little deeper so it's bigger but I think it will still fit correct?
http://www.dometic.com/enus/Americas/USA/RV-Products/refrigerators/Refrigerator-Product-Display/?productdataid=71043


Norcold:

323T - This one will fit and is similar to the 2193 above
http://www.thetford.com/Home/Products/NorcoldRefrigeratorsHome/323T/tabid/209/Default.aspx

N300/N302 - This is similar to the 4223 above so it may be too deep
http://www.thetford.com/Home/Products/NorcoldRefrigeratorsHome/N300/tabid/208/Default.aspx


Are there any other options? I can't remember what the dimensions of the cabinet area is so I'm not sure if the deeper ones will fit or not. Anyone out there have one of the deeper ones in a Burro from the same time period as mine?

Thanks for the help!

Rob