Helium Absorption Refer

[hohenwald48]

My motorhome came with an Atwood helium absorption type refer. It works just like the ammonia type refers without the dangers of leaking ammonia. At least that's my understanding.

I've had the motorhome for about a year now and can't see any difference in performance or operation over the many ammonia units I've had in the past. Seems to me it would be a good solution for those with failed ammonia refers. Fits in the same cut-out and uses the same electrical and propane connections.

I never see any discussion of this type refer on any of the RV forums. Any reason why it doesn't seem to be in widespread use?

[MotorPro]

Just more expensive ....work great

[Sudsy]

Folks only tend to post complaints about things that break.

[nothermark]

It's one of the options mentioned if moving to an Amish cooling unit for an existing absorption refrigerator. The ammonia is still there but they use helium as the gas instead of hydrogen. The flammability issue is the hydrogen gas leaking. As far as I can tell the only issues are cost and availability of the helium.

FWIW - From what I have gleaned - there are a lot of happy absorption refrigerator users out here. The real problem was that the bean counters got too far into engineering the Norcold 1200 double door. That resulted in sub standard tubing that corrodes and fails. Folks looking for an alternative found the Samsung unit and started singing it's praises. That hooked the "can't leave it alone" crowd. Now we are dealing with the aftermath in the form of the increased electrical load.
Ammonia based cooling goes back as far or farther than compressor based systems. They were used in the early ice plants that are still in commercial use. They are just over engineered by today's limited life designers. Point is to blame the right folks.

[Gary RVRoamer]

My motorhome came with an Atwood helium absorption type refer. It works just like the ammonia type refers without the dangers of leaking ammonia. At least that's my understanding.

Not quite accurate. It still has ammonia as the basic gas, but it uses helium in place of hydrogen as the secondary "helper" component. It's the hydrogen that is so easily ignited in a leak, so the helium is much safer in that event. Helium doesn't help as much as the hydrogen in the gas absorption process, but your report indicates it works well enough. At least in a typical usage environment.

[harleyjt]

Originally Posted by nothermark

It's one of the options mentioned if moving to an Amish cooling unit for an existing absorption refrigerator. The ammonia is still there but they use helium as the gas instead of hydrogen. The flammability issue is the hydrogen gas leaking. As far as I can tell the only issues are cost and availability of the helium.

FWIW - From what I have gleaned - there are a lot of happy absorption refrigerator users out here. The real problem was that the bean counters got too far into engineering the Norcold 1200 double door. That resulted in sub standard tubing that corrodes and fails. Folks looking for an alternative found the Samsung unit and started singing it's praises. That hooked the "can't leave it alone" crowd. Now we are dealing with the aftermath in the form of the increased electrical load.
Ammonia based cooling goes back as far or farther than compressor based systems. They were used in the early ice plants that are still in commercial use. They are just over engineered by today's limited life designers. Point is to blame the right folks.

Really? I wouldn't think it would be much more if any more. When I hook up at a campsite, my Norcold switches to electric power as well. So whats the difference? The current residential refers are really quite efficient. I'm not really sure how about the Norcold. I would think though that the usage would be comparable.
jt

[MSHappyCampers]

Originally Posted by Gary RVRoamer

Not quite accurate. It still has ammonia as the basic gas, but it uses helium in place of hydrogen as the secondary "helper" component. It's the hydrogen that is so easily ignited in a leak, so the helium is much safer in that event. Helium doesn't help as much as the hydrogen in the gas absorption process, but your report indicates it works well enough. At least in a typical usage environment.

X2!

[hohenwald48]

Well, now I've learned my thing for the day. I had no idea that they both contained ammonia or that it was hydrogen causing the fire issue. Thanks for the info.

Before I bought my motorhome it had been broken into at a storage lot and the refer and generator were stolen. As a result, it had a brand new refer and generator when I bought it. As far as I can tell, it performs just like all my previous RV refers.

[hohenwald48]

You'd think they'd have learned something from the Hindenburg.

[nothermark]

Originally Posted by harleyjt

Really? I wouldn't think it would be much more if any more. When I hook up at a campsite, my Norcold switches to electric power as well. So whats the difference? The current residential refers are really quite efficient. I'm not really sure how about the Norcold. I would think though that the usage would be comparable.
jt

It's not an issue when hooked up at a campsite. It is an issue when dry camping. That is when you need extra batteries to keep the residential happy.

Some very rough numbers are that the absorption draws something around an amp to run the controls and does the rest with propane. The compressor draws around 10+ Amps at 12 VDC to provide an amp at 120 VAC. For a 10 hour overnight that's 10 Amp hours of battery capacity vs 100 Amp hours. In anything smaller than a DP they had to double the battery capacity to make it through the night. AFAIK DP's get a couple of extra batteries.

Both cycle their power draw depending on how much work they are doing to transfer the heat out of the box. The difference is that the gas unit shuts down the gas valve saving power when off. The residential kicks on heaters to do the defrost cycle thus drawing more power for short periods. That is why nobody publishes the current draw. They publish long term power usage instead.

Both types can have very efficient boxes and cooling systems. Given the other problems around the Norcold 1200 I suspect they cheated on the box insulation as well as cooling capacity. That is a model specific issue not a type of cooling issue. The single door plus freezer units we have had worked/work fine at keeping the ice cream cold and the refrigerator not freezing the veggies or milk.

[twinboat]

Originally Posted by nothermark

Some very rough numbers are that the absorption draws something around an amp to run the controls and does the rest with propane. The compressor draws around 10+ Amps at 12 VDC to provide an amp at 120 VAC. For a 10 hour overnight that's 10 Amp hours of battery capacity vs 100 Amp hours. .

They are very rough numbers.

I know you later mentioned that the compressors cycle on and off, but to start with 100 AH in 10 hours, for the residential fridge is way off.

Most residential fridge compressors only run 1/3 the time, probably less overnight. That drops your 100 AH down to 33.3 AH in the 10 hour span.

Sure there is some defrost cycle current draw but nowhere near 66 AH.

The energy guide that comes with any fridge will tell the whole story. If it uses 365 KWH a year, that's an average of 1000 watts a day. That's 83 AH in a 24 hour day. Add some inefficiencies and its still less then 50 AH in that 10 hour overnight.
Even a large fridge using 50% more power then my numbers will use less energy then your " very rough numbers ".

The great thing about residential fridges is that almost everybody has one. If your thinking about installing one in an RV, you can buy a $25 Kill A Watt meter, plug it in and run the numbers on yours.

[hohenwald48]

I think the whole absorption vs residential discussion is mostly dependent on how you use your RV.

For me, I probably "boondock" 2-3 nights a year. That's usually a short overnight in a Wal-Mart parking lot where I almost always run the generator all night anyway. Occasionally a couple of days at a football game but again I run the generator almost all the time. Every other night I'm plugged into a 50A pedestal. I don't give much thought to energy usage or battery management.

If you spend a lot of time in the desert then I can see how you would have a totally different view.

[twinboat]

I did the gas or electric fridge research because we live 50% off grid on our boat. Gas fridges are not used in boats for insurance reasons. I'm about to swap the gas fridge the a residential in our MH. Its 18 years old and not keeping the temps down.

[Smokyjoe]

I changed to residential fridge 10 years ago. More room inside and works at any outdoor temperature.