Today years old when I discovered what 3-way is

d_v

So I just learned today what the absorption refrigeration cycle is. Before we bought or trailer I was thinking 3-way, that has to be better than two way, right?  It’s an entirely new way, one full way better. And it’s the 2020s, more efficient? Certainly! Easier to use? Definitely! I imagined a compressor and some sort of Bloom Energy thing that changes propane to electricity. Wait, what? All three ways are there just to boil ammonia, with heating elements and burners? That can’t be efficient. 300w?! That’s 2hrs of battery! And this 30a fuse is on the panel where a 20a should be?! And Norcold’s warranty is one year and my trailer is 2 years old? And a DC refrigerator is how much? What a day. All for trying to figure out why 2 buttons on the Norcold touch panel don’t work. Learning about Danfoss compressors now though, and a new respect for propane.

Marceline

d_v said:

So I just learned today what the absorption refrigeration cycle is. Before we bought or trailer I was thinking 3-way, that has to be better than two way, right?  It’s an entirely new way, one full way better. And it’s the 2020s, more efficient? Certainly! Easier to use? Definitely! I imagined a compressor and some sort of Bloom Energy thing that changes propane to electricity. Wait, what? All three ways are there just to boil ammonia, with heating elements and burners? That can’t be efficient. 300w?! That’s 2hrs of battery! And this 30a fuse is on the panel where a 20a should be?! And Norcold’s warranty is one year and my trailer is 2 years old? And a DC refrigerator is how much? What a day. All for trying to figure out why 2 buttons on the Norcold touch panel don’t work. Learning about Danfoss compressors now though, and a new respect for propane.

If you can get your fridge to run on propane you'll be using waaaaaay less power than any 2way fridge. This can be a serious advantage. Will it not run on propane?

d_v

Yes, that was my new respect for propane. We have not tried it on propane yet and it’s covered right now. I doubt it would burn the cover, but don’t want to chance it. It’s been over 100 degrees all but 3-4 days this July/August and 3-way reviews for those temps seem mixed. The two days we took it out it froze everything (on ac power) so that is promising.  The control panel button does not work for selecting the source, it just goes to auto. Hopefully propane is 2nd auto choice.

Mickerly

I think you meant the DC refrigerator will not run on propane. This is the "3-way" advantage.

The DC powered compressor refrigerator is more efficient than a "3-way" operating on DC.

Each design has advantages and disadvantages. The design that is best for you is based on how you operate your trailer. 

Marceline

d_v said:

Yes, that was my new respect for propane. We have not tried it on propane yet and it’s covered right now. I doubt it would burn the cover, but don’t want to chance it. It’s been over 100 degrees all but 3-4 days this July/August and 3-way reviews for those temps seem mixed. The two days we took it out it froze everything (on ac power) so that is promising.  The control panel button does not work for selecting the source, it just goes to auto. Hopefully propane is 2nd auto choice.

The 2way fridges can struggle when the ambient temperature is over 90deg as well. You're really not missing anything by having a 3way fridge. I would absolutely not run it from the battery, though. It's a huge power hog (constant 10-11amps). It's really designed to run in that mode in a vehicle with an alternator supplying it constant DC power, like a motorhome or van. You don't say what trailer or what fridge you have, but if it's a 3way, you absolutely should be able to select the mode (propane or electricity). I would try to get it to work on propane before giving up on it and spending a lot of money on a 2way fridge.

d_v

It’s the 3-way Norcold 4104 in a 2021 400. The touchpad does not work where you select the “source”. It does work where you select the cooling level. Not being able to select the source (stays in Auto) and then looking for the cost for the likely broken part is what took me down the absorption cycle rabbit hole. Yes, the sticker says hungry 16.2a on 12v. The manual says Auto goes AC, DC, propane. I think I have to leave the DC switch off, disconnect the AC and wait for it to try propane. Yes, boondocking is where it will shine. 

Sharon_is_SAM

@d_v - have you seen this thread?  https://tab-rv.vanillacommunity.com/discussion/comment/173046#Comment_173046

GregChris

A "2way" or 12v fridge like the Isotherm doesn't exhaust outside, is doesn't care what outside temp is. It could be 110f outside, but if inside  is 70 to 80 because of ac, that's all the fridge care about.

Marceline

GregChris said:

A "2way" or 12v fridge like the Isotherm doesn't exhaust outside, is doesn't care what outside temp is. It could be 110f outside, but if inside  is 70 to 80 because of ac, that's all the fridge care about.

Plenty of people camp without hookups, which means that they don't have AC (unless using a generator). The fridges for all of the CS T@Bs are in the galley at the back, so they are never in an air conditioned environment. I don't have personal knowledge of the Isotherm, but the Norcold 2way definitely struggles when it's over 90degrees.

Mickerly

We've used ours over 100 without issues. Check your door seal.

SLJ

We boondock so no air conditioning. Out 12 volt Isotherm Stays at about 40 degrees when the inside air is above 90 degrees. Otherwise I have it set for 38 and it will stay there. The Dometic 3 way in our motorhome always struggled on propane when it was hot out and drew too much when on battery. I don't miss it.

GregChris

Didn't think about cs's, sorry.

Marceline

SLJ said:

We boondock so no air conditioning. Out 12 volt Isotherm Stays at about 40 degrees when the inside air is above 90 degrees. Otherwise I have it set for 38 and it will stay there. The Dometic 3 way in our motorhome always struggled on propane when it was hot out and drew too much when on battery. I don't miss it.

How much does the compressor run compared to an ambient temperature of 70 degrees? How much power does it consume at the different ambient temperatures? 

Samrollseyes

I have a 2018 320s with the Norcold refrigerator. I use propane when I'm boondocking and generally my food has remained cold up to an exterior temp of 95 degrees. My biggest issue is my home elevation is about 4800 feet and while camping I go up in elevation. That makes my refrigerator hard to light when I get there. I've not yet put on a flow restrictor on my gas line feeding to the pilot light but I find if I turn the feed on the refrigerator to low-medium flow I can usually start it. I was once desperate enough to run on battery but only to keep the chill in the refrigerator.