12v vs 120v Refrigerator

[ERTF]

I'm looking for testimony regarding performance of 12v fridge/freezer combos (7-10 cu ft range) in hot climates. Mine needs to be replaced and I am debating paying $$$ for an exact replacement vs a 120v apartment fridge.

My boat came with Tundra T80 (8 cu ft) 12v fridge/freezer. It appears a brand named Vitrifrigo sells the identical model now for $1800

My fridge has always struggled to be cool outside of winter (and forget about truly cold ever). The old non-replacable gaskets are surely part of the problem. I do have computer fans for ventillation. Anyway, I'm not really looking for ways to improve the one I have, moreso wondering if it's actually worth paying $1800 for a new one.

My fridge compressor runs 24/7 most of the year & draws 5.35a. 10 cu ft apartment combos are rated 115-125watts. So basically twice the draw of my 12v, especially after accounting for inverter loss. But i'm just wondering if they draw double the current for nothing, or if they utilize the power to cool faster and thus run notably less than a 12v model.

 

[SteveK]

I have the original 120/12 fridge and run it on 12V 24/7 to allow inverter power 120v for other items.
There was a recent discussion on 120/12v v. only 120v AC due to cost and newer have lower power needs and also offer frost free.
From that thread I plan to replace when needed with a straight 120v version due to purchase cost of 60% of 120/12

 

[Jeff F]

My fridge compressor runs 24/7 most of the year & draws 5.35a. 10 cu ft apartment combos are rated 115-125watts. So basically twice the draw of my 12v, especially after accounting for inverter loss. But i'm just wondering if they draw double the current for nothing, or if they utilize the power to cool faster and thus run notably less than a 12v model.

It's not quite that simple. Here's a different but maybe more useful way to approach it.

Your existing unit running continuously uses 5.35*24*12 = 1.54 kwh/day. Compare that to Enerstar ratings on apartment units.

 

[ERTF]

It's not quite that simple. Here's a different but maybe more useful way to approach it.

Your existing unit running continuously uses 5.35*24*12 = 1.54 kwh/day. Compare that to Enerstar ratings on apartment units.

Unfortunately, that's not a like for like comparison because it is 85 degrees in my boat. Also my current unit has gaskets that don't seal perfectly (so a new 12v unit may not run constantly).

 

[SteveK]

Unfortunately, that's not a like for like comparison because it is 85 degrees in my boat. Also my current unit has gaskets that don't seal perfectly (so a new 12v unit may not run constantly).

You are correct, compare the rating of a new 120/12 to a 120v only and then the cost difference. If you find the 120/12 wins out let me know as I have dismissed upgrade to another 120/12

 

[ERTF]

I'm not aware that the RV/Marine units undergo Energyguide testing.

For the vast majority of boaters, an apartment fridge is surely the logical choice economically. My boat has spent 2000 consecutive nights on anchor, so the math is less obvious.

 

[SteveK]

@ERTF and that is why it is difficult to purchase at twice the cost just to be able to run off 12V when you already have an inverter working, maybe have a few solar panels.

 

[Comodave]

We replaced the old Nevercold in our boat a couple of years ago. Since the cabin door opening was only about 22” we had a tough time finding one that would go through the door. My wife found an Isotherm CR271, I think. It was 20” with the doors off. It is almost 10 cubic feet. So I had to modify the cabinet to fit the taller unit. I made the top opening 2” above the refer. The new unit was 2” narrower than the old one so I have an inch opening on each side. I put a 5” computer fan blowing upwards to help move the hot air up. The new unit runs off both voltages. We have always had to run boat refers at the maximum setting. The new unit goes from 1 to 8. We started using it set on 8. It froze everything in the refer compartment. So we gradually turned it down until we got to 3. It still freezes ice cream and cools the refer compartment very well. We are extremely satisfied with this unit.

 

[O C Diver]

Here's my thread on switching to an apartment refrigerator.

My new Apartment Refrigerator

A little background: I had a Norcold DE/EV 0061 7.0 cuft AC/DC refrigerator. The gasket on the freezer door didn't seal completely necessitating that I defrost it every one to two weeks. The gasket isn't sold separately, but you can buy the whole door assembly for a princely sum. I had my...

www.trawlerforum.com

Post #26 explains how before installation, the refrigerator was able to reach operating temperature on an 85 degree day in 30 minutes. Small compressors are a fallacy as they neither maintain temperature in hot environments nor are able to reduce warm groceries to refrigerator temperature in a reasonable time. Far better to have a larger compressor that has short run times, than a small compressor that runs continuously.

Ted

 

[CaptTom]

It still freezes ice cream and cools the refer compartment very well. We are extremely satisfied with this unit.

This is what has me considering swapping out a dedicated RV/Marine fridge for an apartment-sized unit. I do like not having to run it off the inverter though. I wish there were a 12/120 fridge which fit in the existing space the N'ercold takes, but actually freezes to zero F and keeps the fridge section a constant temperature even when it gets hot in the cabin.

 

[rslifkin]

This is what has me considering swapping out a dedicated RV/Marine fridge for an apartment-sized unit. I do like not having to run it off the inverter though. I wish there were a 12/120 fridge which fit in the existing space the N'ercold takes, but actually freezes to zero F and keeps the fridge section a constant temperature even when it gets hot in the cabin.

My Novakool fridge (model RFU9000) comes close. A bit of added insulation and some changes to the fan setup helped performance significantly in hot weather. They now make a version with separate fridge and freezer compressors (RFU9200) which should give a bit better performance (more total cooling power) and separate freezer temperature control (which should allow a lower freezer temp without freezing food in the fridge).

 

[Kaniksu]

I recommend Summit Appliance if you decide to go with an AC fridge/freezer. They are quality made (U.S. Company) and they have a wide variety of sizes. They also make outdoor units intended for patios and bars. I replaced a noisy old Norcold with with a 4.8 cu. ft. freezerless fridge as we simply don't use the freezer. What I love about it is that it is counter depth, it is intended to be be installed in a zero clearance tight place and it vents from the bottom and needs no additional fan. It is also silent and holds 38 degrees on the hottest of hot days. I know others here have used Summit as well. Have a look.

 

[ranger58sb]

I recommend Summit Appliance if you decide to go with an AC fridge/freezer. They are quality made (U.S. Company) and they have a wide variety of sizes. They also make outdoor units intended for patios and bars.

We just replaced the boat's original Sub-Zero undercounter freezer with a Summit Outdoors undercounter freezer. AC only (as was the Sub-Zero), same dimensions, icemaker option, locking door, choice of full stainless cabinet or stainless door only with black metal cabinet. (We chose the latter, pretty much what the Sub-Zero was.)

Cost was approx same as the Sub-Zero repair estimate. About half the cost of the new Sub-Zero "similar but lower capacity" model. Seems good quality. (Pretty sure I saw a "Made in China label on it.... not an issue I care about.)

-Chris

 

[Jeff F]

This is what has me considering swapping out a dedicated RV/Marine fridge for an apartment-sized unit. I do like not having to run it off the inverter though.

If you're not already running the big inverter all the time a dedicated small inverter for the fridge may be a good solution. Lower overhead, and easy to install. Check specs, but 500w is plenty. It's been discussed here.

 

[Comodave]

What I have found to make a significant change in the refrigerator performance is to have 2 vents, 1 low for cool air intake and 1 high for hot air exhaust. I also add a small draw computer fan to help move the hot air up and out of the compartment. The fan I use draws 50 mAmps so it is insignificant in power consumption. This is the one I use from Amazon.

Noctua NF-F12 PWM, Premium Quiet Fan, 4-Pin (120mm, Brown)​

 

[SteveK]

We replaced the old Nevercold in our boat a couple of years ago. ..............

Dave, why do you and others say Nevercold. Do they have that rep?
Am I the only one that has a 33 year original Norcold that can become a freezer in the main compartment? Of course I cannot tell if the thermostat was changed but compressor shows no sign of being changed. It runs 24/7.

 

[Comodave]

I have had several of them in our 24 boats and never had anything good about them. Always had to run them on the max setting and still didn’t freeze ice cream, that is my go/nogo decision. But with our new, several years ago, Isotherm we only run it on 3 out of 8. And it freezes ice cream. Maybe you are the lucky guy???

 

[CaptTom]

My experience is the same as Dave's. The Norcolds I've known work fine, but you have to run them almost all the way on high, and still the freezer barely gets below freezing. Not cold enough for ice cream or many other frozen foods, which like to be at zero F.

Hence the "Nevercold" or "N'ercold" monikers.

 

[ranger58sb]

We just replaced the boat's original Sub-Zero undercounter freezer with a Summit Outdoors undercounter freezer. AC only (as was the Sub-Zero), same dimensions, icemaker option, locking door, choice of full stainless cabinet or stainless door only with black metal cabinet. (We chose the latter, pretty much what the Sub-Zero was.)

Cost was approx same as the Sub-Zero repair estimate. About half the cost of the new Sub-Zero "similar but lower capacity" model. Seems good quality. (Pretty sure I saw a "Made in China label on it.... not an issue I care about.)

-Chris

I wandered off... meant to say, more on topic, that we've come to appreciate the frost-free feature that we've never had on previous and current Norcold and NovaKool AC/DC units.

-Chris

 

[ERTF]

Dave, why do you and others say Nevercold. Do they have that rep?
Am I the only one that has a 33 year original Norcold that can become a freezer in the main compartment? L

Probably because you are not in a hot climate.

 

[Ithaka7]

It comes down to cost. The volume of 12/24V fridges is very small and good ones cost Eur 1,000+ where I live. Households fridgers come in lots of styles, have better insulation and cost Eur 100 where I live, so easy to replace. The efficiency is smilar (newer fridges have better motors but less efficient refrigerants, so it evens out). I could not start an 85W 220v fridge on a 500W Victron sine wave inverter but a 1,400W inverter from a no name company works well. You need an inverter on the boat anyway for the coffee machine, the vacuum, occasional electronics. I would go with 220v if space permits.

 

[rslifkin]

newer fridges have better motors but less efficient refrigerants, so it evens out

That has been true up to a point, but some newer stuff that uses R600 seems to be a significant jump in efficiency. Comparing 2 ice makers, one using R134a and one being a slightly newer model with R600, the R600 unit uses significantly less power overall.

 

[3rdOrderEffect]

Dave, why do you and others say Nevercold. Do they have that rep?
Am I the only one that has a 33 year original Norcold that can become a freezer in the main compartment? Of course I cannot tell if the thermostat was changed but compressor shows no sign of being changed. It runs 24/7.

I have a ~22 year old Norcold on my boat that works fine. The previous owner changed something on it because it only runs off 12v now so maybe that’s why it works well, I can’t say.

 

[Ithaka7]

That has been true up to a point, but some newer stuff that uses R600 seems to be a significant jump in efficiency. Comparing 2 ice makers, one using R134a and one being a slightly newer model with R600, the R600 unit uses significantly less power overall.

You are right, the R600a is a very efficient refrigerant and it also operates at lower pressures. Here is what I found on the web. Standing pressure for R600 is 50 psi, for R134 is 90 psi and for R410/R454 is 220 psi. The efficiency is R600 > R410 > R134. The point is that R22 was a very efficient gas. The replacement R134 operated at similar pressures but was less efficient. Then we went up to R410 which improved the efficiency to R22 levels but increased noise levels (this is why in general older AC units are quiter than new units, despite what the manufacturers say). Today, there is no practical replacement for R22 that has efficiency, low noise and is not bad for the environment, at least not one that I know of.

R600 is a great solution for fridges and smaller systems but because the gas is flamable and heavier than air, it is only advisable to have a limited quantity of it and in general you will not find a marine fridge or AC unit with R600, hence your best bet for efficiency/noise levels is to get a household R600 unit. For larger systems, it is better to stay with R134 for as long as possible and resist the move to R410/R454 if you want low noise.

 

[Bmarler]

Dave, why do you and others say Nevercold. Do they have that rep?
Am I the only one that has a 33 year original Norcold that can become a freezer in the main compartment? Of course I cannot tell if the thermostat was changed but compressor shows no sign of being changed. It runs 24/7.

I sold my sailboat that had a 35 plus year old norcold still working flawlessly. Always had the thermostat set to 3, run it 24/7 all year long, year after year.

 

[SteveK]

I sold my sailboat that had a 35 plus year old norcold still working flawlessly. Always had the thermostat set to 3, run it 24/7 all year long, year after year.

Looked it up

Norcold, which was founded Oct. 15, 1959, in California, is celebrating 60 years of manufacturing specialty refrigerators for the RV, marine, and mobile markets.

Operations moved to Sidney, Ohio, in 1964, which remains the company’s largest manufacturing facility. In 1997, Norcold was purchased by Thetford Corp.

Those of us with pre 1997 units are still operating well were made in the USA. Since then Thetford Corp gets parts from China but there is no internet found manufacturing locations anywhere listed.
So maybe those sold since 1997 are the ones that are nevercold

 

[SIBERNUT]

Just to add another thought - there is a company that will reconfigure your existing RV (boat?) unit to a new better compressor. A lot of the RV units are built in and NOTHING else fits.

 

[Mambo42]

I guess it all depends on the amount of space you have and the amount of money you want to spend. All my freezers and fridges are normal household equipment, run on 220V, use about 9 to 10 amps per hour at 24 V (when I convert it). My inverter can handle 8000 W, so the 200 - 250 W these coolers use are no problem for the inverter. The batteries have 1400 AH, so 10 amps per hour is not going to kill me. And the solar panels deliver (in summer) around 15 - 20 kw per day, which means I have no problems regenerating the electricity the coolers use.
If I would have a smaller boat, a small inverter, perhaps I would choose a small 12 V fridge. But indeed, they are very expensive and if the break down you really will spend a lot of money getting them back to life, since spareparts are very difficult to find.

 

[3rdOrderEffect]

I have a ~22 year old Norcold on my boat that works fine. The previous owner changed something on it because it only runs off 12v now so maybe that’s why it works well, I can’t say.

Oops, looks like I misspoke. I am on the boat and checked, turns out my galley fridge is actually a 23 year old Nova Kool.

She works great tho

 

[ranger58sb]

We had NovaKool units on our last boat, and both worked fine. Had to deal with frost buildup, though, especially the double door unit... since that one saw more open/close activity.

-Chris