Advice wanted

[Sooperdrave]

2 way vs 3 way fridge?
The 2 way in my van works but I'm thinking of putting a 3 way in it...
Also, what size generator should I be looking at to run the fridge, lights, and AC?
Solar generators?
Solar systems?

[BBQ]

Originally Posted by Sooperdrave

2 way vs 3 way fridge?
The 2 way in my van works but I'm thinking of putting a 3 way in it...
Also, what size generator should I be looking at to run the fridge, lights, and AC?
Solar generators?
Solar systems?

3-way is passé.

[InterBlog]

I've owned three van fridges thus far -- two 3-ways and one 2-way. My suggestion is that, before you make your decision, you skim the following:

(1) This blog post of mine (here), in which I discuss all three of our fridges.

(2) This thread (here) about the performance of the Dometic 2351. That model or its successor is one of the most commonly-installed 3-ways in vans due to its small size, and the application being discussed in the thread is not entirely the fault of the installation method being discussed - part of the problem is deriving from the fridge itself. I say "skim" because that one has 351 posts. Ask yourself: why would any fridge justify 351 posts?! Answer: a lot of frustrated users.

(3) This forum thread (here) where the pros and cons of both fridge types are debated. It includes some commentary on failure modes and come-backs (failed fridges still under warranty). This thread was initiated by a poster who had a 2-way and was considering swapping it for a 3-way, so you'll immediately see the proper-context issues raised in it.

[avanti]

This may be too late, but I would like to suggest that the term "2-way" is not the best choice as a label for a compressor fridge. There exist 2-way absorption fridges: my old rig had one that was propane/120VAC only. Also, there are lots of compressor fridges that are "1-way" (12VDC only). Moreover, as I have said, the 120VAC input to a compressor unit is largely irrelevant to B-vans.

"3-way" is probably OK as a synonym for "absorption", since all 3-ways are absorption and not everybody knows the latter term. However, IMO, we should use the term "compressor" when that is what is meant.

I hope I am not being pedantic, but I have been genuinely confused by this use of "2-way".

[cruising7388]

Originally Posted by avanti

This may be too late, but I would like to suggest that the term "2-way" is not the best choice as a label for a compressor fridge. There exist 2-way absorption fridges: my old rig had one that was propane/120VAC only. Also, there are lots of compressor fridges that are "1-way" (12VDC only). Moreover, as I have said, the 120VAC input to a compressor unit is largely irrelevant to B-vans.

"3-way" is probably OK as a synonym for "absorption", since all 3-ways are absorption and not everybody knows the latter term. However, IMO, we should use the term "compressor" when that is what is meant.

I hope I am not being pedantic, but I have been genuinely confused by this use of "2-way".

I think the evolution to "2 way" from "3 way" occurred because the 12 volt mode caused more problems than it solved. Typical 12VDC drain on a Dometic is in the neighborhood of 15 -20 amps. The better designed "3 ways" required ignition on for 12V operation (which presumably would mean engine running and alternator support)) Also, the 12V boiler BTU is substantially lower than the AC boiler BTU so the practical consequence is that the 12V mode can do little more than hold an existing fridge temp.

[Sooperdrave]

Originally Posted by avanti

This may be too late, but I would like to suggest that the term "2-way" is not the best choice as a label for a compressor fridge. There exist 2-way absorption fridges: my old rig had one that was propane/120VAC only. Also, there are lots of compressor fridges that are "1-way" (12VDC only). Moreover, as I have said, the 120VAC input to a compressor unit is largely irrelevant to B-vans.

"3-way" is probably OK as a synonym for "absorption", since all 3-ways are absorption and not everybody knows the latter term. However, IMO, we should use the term "compressor" when that is what is meant.

I hope I am not being pedantic, but I have been genuinely confused by this use of "2-way".

By 2 way, I mean that my fridge is shoreline or propane only. Neither can be used while I'm driving.
By 3 way, I'm talking about shoreline/propane/12vdc that can run while I'm driving/idling.

Sorry, I'm pretty new to all this.
I would like to be able to keep the fridge running as much as possible.
Is taking out the working "2 way" and replacing really going to be worth the trouble or expense?

[avanti]

Originally Posted by Sooperdrave

By 2 way, I mean that my fridge is shoreline or propane only. Neither can be used while I'm driving.
By 3 way, I'm talking about shoreline/propane/12vdc that can run while I'm driving/idling.

Sorry, I'm pretty new to all this.
I would like to be able to keep the fridge running as much as possible.
Is taking out the working "2 way" and replacing really going to be worth the trouble or expense?

My apologies. I totally misinterpreted your question -- your terminology is correct. I was the confused one.

Now that I understand:
Do you have an inverter (converts 12VDC to 120VAC)? If so, turning it on should allow you to power the fridge in 120VAC mode. If not, adding one would probably be cheaper and easier than replacing the fridge.

[Sooperdrave]

No it does not have an inverter. I didn't even think of doing that. I'm sure I could wire one up easily enough. What size inverter would you suggest?

[avanti]

Originally Posted by Sooperdrave

What size inverter would you suggest?

Depends on what you might do with it. If it is just for the fridge, just look at the power spec for the refrigerator and round up. If you have other uses for the inverter (and have the battery to support it), then the sky's the limit.

[Sooperdrave]

I'm adding 3 batteries and a 300 watt solar system. I'm thinking an inverter that is big enough to run the fridge and AC...

[dhectorg]

Originally Posted by Sooperdrave

2 way vs 3 way fridge?
The 2 way in my van works but I'm thinking of putting a 3 way in it...
Also, what size generator should I be looking at to run the fridge, lights, and AC?
Solar generators?
Solar systems?

The absorption fridge (propane) in the RV we had when I was a kid was a nightmare. It seemed to never work right and was extremely finicky about being level. I know they've improved over the years, but I will never own one because of those memories from 20 years ago, as well as countless accounts of fridge woes on YouTube. Personally, I'd only have a 2-way compressor based fridge, 110v and 12v.

[eric1514]

At the risk of starting an argument let me ask, "Why don't you run your refrigerator on propane when you drive?" It was designed for that.

[wincrasher]

If you have 200 watts of solar and 2 house batteries, then a 2 way fridge is virtually worry free. It's more than enough to keep ahead of the fridge's power consumption, plus you have the battery capacity to carry you over 2-3 days of no sun.

[eric1514]

Originally Posted by wincrasher

If you have 200 watts of solar and 2 house batteries, then a 2 way fridge is virtually worry free. It's more than enough to keep ahead of the fridge's power consumption, plus you have the battery capacity to carry you over 2-3 days of no sun.

Except that by “2 way”, the OP means an absorption refrigerator that runs on 110v or propane.

[hepcat]

Originally Posted by eric1514

At the risk of starting an argument let me ask, "Why don't you run your refrigerator on propane when you drive?" It was designed for that.

There are LOTS of reasons not to run a fridge on propane while you drive. Most of them involve the threat of fire/explosion hazard/risk if something goes wrong.

That said i've always run my fridges on propane going down the road, and never had an issue in nearly forty years of RV'ing. I've had a variety of 2-way and 3-way fridges over that time. Frankly, the 12v setting is pretty much useless, which is why I run on propane when driving.

[JohnnyFry]

I use Propane while driving all the time, it works fine.

[Doneworking]

I run our RT on 12 volts going down the road if the refrig is already at its usual high 30s temperature. On a very hot day, the temp will go up five or so degrees. Nothing is going to rot that I know of in a few hours at a temp in the low 40s.

The reason I do that instead of propane is because you have to remember to turn off the refrig on propane before pulling in to buy gasoline. However, running down the road on propane is perfectly acceptable in my mind. On our Class Cs over the years I have had two way (110v/propane) refrigs and I just run them on propane virtually all the time. They are very efficient on propane.

You can increase the efficiency on 12 volts by adding a little 12 volt fan (directed towards the roof) at the bottom of the refrigerator. You have 12 v back there and it is a $20 deal to put in a little electronic equipment fan and a simple on off switch. This little assistance to the upper flow of heated air seems to help my RT on 12 v quite a bit.

I don't personally understand the fear of propane. Around here (Oklahoma City) several major companies run most of their fleets on compressed natural gas (CNG) and fill up stations are readily available. In all those years this has been going on, I don't think I ever heard of an accident caused by CNG. UPS runs their delivery trucks on CNG. CNG psi is generally 3000 at 70F ambient as I recall.

Maintenance of the propane system in a RV of any description is essential. I check every connection and line on my rigs with soapy water at least once a year (generally every spring).

I guess I have just used propane so many decades I never give it a thought except to follow the normal safety standards rigorously.

Paul