Why no Residential Fridges?

[Cadence]

Originally Posted by Cat nap2

I have small propane ref on my cat. Does any one else have experience with propane?

You are probably speaking of an a unit using ammonia as a refrigerant. On a cat probably works well since it needs to be somewhat level. It probably also works on 12V which is not much more than a heat tape. Basically what has been used in RVs for years.


Dormetic comes to mind?

[four winds]

Originally Posted by Cat nap2

I have small propane ref on my cat. Does any one else have experience with propane?

Factory install next to the companionway? I forget the make, but if it's the one a friend had it's dangerous. It's a rv fridge designed to be mounted in an outer wall. This allows combustion gases to escape outside.

The cat maker did not do this. Instead a vent was behind the fridge in the cabinet top. The manual says to open the window next to the cabinet when using the fridge.

Was rafted up with a friend one night when he almost kills himself with the fridge first time he used it. Barely conscious when I went aboard. Fresh air and thirty minutes later he had recovered.

[belizesailor]

Originally Posted by Cat nap2

I have small propane ref on my cat. Does any one else have experience with propane?

Ive used them ashore, but not on boats. Maintenance is very important to maintain operating efficiency and reducing fire hazard. Mine ashore got spendy to run when propane prices rose...not so bad if just using for a weekend, but this was in full time use.

Friend nearly burnt her house down with a poorly maintained and modified one.

[kismet]

As to the Edgestar. I had one, quite as soon as the warranty ran out, no help from the company. Chinese junk.

[darylat8750]

I looked into propane refer. A friend who lives remotely in the mountains used one for years and was happy with it. I couldn't figure out how I could reasonably vent it so no go for me. Also solar has advanced to the point that the (already small) market for propane refrigerators has dried up.

[jeepbluetj]

Originally Posted by a64pilot

I believe the frost free part is done literally by resistance heating, and if that's true I can see how that part uses more energy than the compressor, but I believe there are units that have an energy saving setting that turns off the frost free part.
I think even the seals may be heated?

The frost-free system is indeed basically a resistance heater around the evaporator, a timer that turns it on, and a sensor on the evaporator that turns the heater off if it gets too hot.

Yes, it takes quite a bit of juice. But only once a day for 15-30 min or so. Never seen one with a switch, but you _could_ bypass it by removing a wire to the heater. You'd get a block of ice completely covering the evaporator within days though.

The seals are commonly heated to reduce condensation. (It's called the stile heater) On big U.S. style domestic units that is commonly a resistance heater and it's what is turned off in 'energy efficient' mode. On cheaper units around 10cf or so, the stile heat is just part of the condenser. i.e. a condensor tube run between the fridge and freezer door.


My Boat:

On my boat, I've got a Norcold icebox conversion fridge. Aircooled. Pulls 6A or so when running. Duty cycle is around 60% or so. (Yes, I need better insulation) With 200W of solar I can run it for 2-3 days before the batts are pulled down too much for my comfort. Manually turning it off at night, then letting it get waaaaay cold when it's sunny. All lights on the boat are now LED, no significant other draw when on a cruise. 220AH battery bank.


Semi-Related Long RV story to prove domestic fridges work:

My RV had the standard Dometic propane thing. It was awful. Had to be perfectly level. Didn't get very cold - couldn't have ice cream. Took 24 hours to cool down. Used lots of propane. Pulled 12v of about .5A not running, 2-3A when running. Was a major fire hazard. When it died I was very happy (wasn't all the way dead, but don't tell my wife that)

I replaced it with Vissani 9.9 cu. ft. Top Freezer Refrigerator in Black-HVDR1040B - The Home Depot

For basically the price of a new propane unit (which would still suck) I got:

1. The new residential fridge
2. 480 watts of solar
3. 2000W PSW inverter
4. 30A MPPT controller (Midnite solar kid)

RV only has 220AH battery bank, I've got room for 2 more GC6s but I haven't added them yet 'cause we haven't needed them.

In so cal, I can pretty much run that fridge and the rest of the RV forever. We don't plug in if we've got hookups unless we want to run the AC. Overnight drop is around 30ah running the fridge off the batteries. Batteries fully charged (float) by 1-2 pm or so the next day - even with a pretty good overcast.

Fridge pulls ~8A (12v) once it's running. Defrost pulls more, but it's rare. Inverter overhead is worse than the defrost overall ('bout .5-1A). Duty cycle is less than 30%. It'll keep ice cream hard as a rock. It cools down in an hour or so. It's 4cf bigger so I no longer need a cooler for beer. If it breaks, it's a $300 unit to replace. Better all around.

If I had to put something in a boat now

For a cat, if there was somewhere to put a domestic fridge I wouldn't hesitate to use one and plaster the bimini with solar.

Drop-in top-load Engel would be the shizznat IMHO on a mono or a cat. (I've used em a lot jeeping) 3-5A draw, around 30% duty. And very reliable. Would be much less power than a domestic fridge. You can drop in a new one or work on it out of the boat if it breaks.

I don't think I'd go to any watercooled solution. I'd be worried about corrosion on a keel cooler, and a pump type system seems like overkill. Dedicated marine style units are also pretty expensive, making the Engel look better to me.

[Lepke]

It's a matter of space and power. It also depends on your comfort expectations and pocket book. Most boats don't have the room for a house type frig. Inverters have become much better so maybe we'll see changes in interior design to make room for larger refrigerators.
I am retired and wanted comfort, so picked a boat I could have a 2 door frig, washer, dryer and dishwasher. I also mainly use 120 volt lights because I don't like the dc options. And I am not rich. With my old inverter/batteries, I could go 2 days without running a generator. The new setup goes about a week if I'm not running a freezer.

[SeaSon]

The PO of my trawler installed the Norcold RV version fridge that could also run on propane.

The propane was never hooked up. It used heat to cool the box (ammonia/evaporation?).
1. Drew 30+ amps of converted dc (~3 amps of 120v)
2. Generated huge amount of heat, like 'holy crap, that thing is really hot and so is the wall and anything near it'.
3. Never got very cold when the boat was underway as they have to be very level to operate. Milk bad in 2 or 3 days.
-Moral: don't use evaporative refrigerators.

Put in a 5.5cu ft Magic Chef as the marine Norcold was 2" taller and it was time to get off the dock. MC not made for inverter use, but can make ice cubes for the Captain and keeps food fresh. Draws less than 5.5 amps dc . Maybe 50pct duty cycle.

FWIW, We live aboard traveling or at anchor 90pct this summer on the Chesapeake and it is working fine.

[SV THIRD DAY]

I shouldn't do it...but I will...I'll expose my evil dark side as an off the grid, doomsday prepper show vendor.....

We can barely fill orders for these fast enough, basically here's what we do.Take an off the shelf 120v AC refrigerator, rip out the 120V AC compressor and then install a 12v DC compressor like a Danfoss BD35/50 or Cubigel.

12v Solar Refrigerators and Freezers for Off the Grid Living

Rich...Rich...Rich....you are crazy. Why would I pay $995 for one of these?

A) Yes of course I'm crazy, but have you ever been to a doomsday prepper show or talked to the off the grid in the Mojave desert folk that are buying these units like hot cakes? They make me almost look sane!
Add in a 140W solar panel and battery and boom, no power no problem.
If I could build in a gun-hide-a-box in one of these I would be a millionaire!
(and YES more than one client has asked...ha ha ha)

B) Then don't pay me...do it YOURSELF! This is totally something you can do yourself folks, it ain't rocket science and I would be happy to help walk you through it. The "hardest" part is just getting access to a vacuum pump if you don't have a buddy with one and then taking your time in balancing the right charge.

Depending on the brand you will use from 25% to 43% less power (what we tested) than running the 120v AC compressor through an inverter.

Is that worth the money for that savings and to be all back to 12v again?
That's your call, but we literally can't keep up with making these 120v AC to 12V DC conversion units. The RV remodel folks love them and we have them all around in doom day bunkers...no joke.

When you price it out if you did it yourself:
Box of your liking $150
Compressor $245
Controller $235
Misc schrader valve, fittings, etc $20
Parts $650

So at $995 we are charging basically $345 for the labor to do the work, know how, and bench testing. It's not going to make anyone "rich" but it keeps one of our guys busy 40hrs+/week. We always joke, "doing a job Americans won't do...actually building something in California"....

[jhnhll]

I was just wondering. If you wanted to keep your top loaded box and had one of the larger dorm size units how hard it would be to use the boats box and the fridge parts?


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[newhaul]

The Engel units are great however the dropins are by far to small for most of my customers. I have installed one of their conversion units in a 3.5cf top load fridge side and a 2cf freezer side it preformed poorly and the this had 6 plus inches of foam all around with at least 4 in the bottom on a Dickinson ketch also installed two 85 watt solar panels that were not quite enough to carry the fridge I installed a technautics in a 7 cf fridge spill down unit with 2.5cf freezer keeps ice cream just fine. With 2.5 inches of foam front load unit with 200 watts of solar carrying the whole boat haven't needed to plug in or charge with the main since install in February here in Tacoma WA

[jeepbluetj]

Originally Posted by SV THIRD DAY

I shouldn't do it...but I will...I'll expose my evil dark side as an off the grid, doomsday prepper show vendor.....

We can barely fill orders for these fast enough, basically here's what we do.Take an off the shelf 120v AC refrigerator, rip out the 120V AC compressor and then install a 12v DC compressor like a Danfoss BD35/50 or Cubigel.

Now that's pretty awesome.

What refrigerant? I was thinking along the same lines but the boxes I was looking seemed to have R600a, and I know nothing about dealing with that.

[SV THIRD DAY]

Originally Posted by jhnhll

I was just wondering. If you wanted to keep your top loaded box and had one of the larger dorm size units how hard it would be to use the boats box and the fridge parts?

Have tried that myself, but the way these dorm units are built it is damn near impossible to get the refrigeration system separated from the "Box" without damaging the lines or parts. Like most things these days, these small units are built as throw away if they fail and not with servicing in mind. The condensing part of the system is embedded on top of the insulation and right under the side wall skin. But if you are able to solder any broken pieces back together...sure, why not? Just don't be doing it for an efficient unit... Take a look at the size of that nice evaporator in the unit we use as a refrigerator.

Originally Posted by jeepbluetj

What refrigerant? I was thinking along the same lines but the boxes I was looking seemed to have R600a, and I know nothing about dealing with that.

The boxes we do the conversion on are all using R134a.
Of course you can't do a full size home refrigerator because the 12v DC compressor just won't have enough BTU capacity...but for these small boxes...heck it works like a dream.

[bobw100ton]

I'm assuming this forum is principally cruising boats, where the design concept does not involve a shore cord. NMMA has stats confirming that the majority of boats are owned for 3 years and that most due little more than anchor out overnight. For that reason a boat builder would be foolish to install a more expensive keel or water cooled condenser to amplify efficiency for a customer who is not micromanaging power consumption. Efficiency is not cheap because the economy of scale doesn't work in favor of the cruising sailor. A 115 VAC air-cooled hermetically sealed home refrigerator compressor built into a enamel painted steel front load refrigerator is a far cry from the efficiency of a hermetically sealed modulated DC to 24vac compressor (such as the most common German made Danfoss compressor) when water cooled. The only thing they have in common is the black paint on a hermetically sealed case. I assure you that buying on the cheap with the refrigeration and box design (insulation is cheap and makes the biggest difference in power consumption) will cost you much more in the long run if you are truly designing for offshore efficiency rather than cruising from shore cord to generator and back to shore cord.

[valhalla360]

Originally Posted by darylat8750

I looked into propane refer. A friend who lives remotely in the mountains used one for years and was happy with it. I couldn't figure out how I could reasonably vent it so no go for me. Also solar has advanced to the point that the (already small) market for propane refrigerators has dried up.

We have them on the boat and the RV.

Silent and no moving parts. As long as you can safely vent them and keep them upright (monohulls need not apply), they work great. When at anchor we get 2-3weeks out of a tank of propane.

The original premise that RV's are switching to residential is largely limited to high end RV's that are either running the generator or hooked up to power continously. Your typical RV's still use the propane/electric units.