Refrigeration: convert ice box or install under counter frig or drop in frig?

[TheOffice]

My C&C 35 has a large ice box. I'm thinking of adding refrigeration. Am I better off adding a compressor and plate or an under counter refrigerator or drop in unit?

[Sumner]

Our Endeavour had/has an ice box ....



...back in that corner under the right arrow and is hard to get to and deep and hard to reach the back and bottom. We decided to just use it for storage in the future.



There was also an upright 12 VDC/110 VAC fridge where the two left arrows were above. It was not insulated well and inefficient with the front opening door.

We made a new fridge that slid into that opening and also extends past it ....




...for more counter space. It is one large box with two openings...



...the one above is in the old counter-top and is to the freezer section and where we store items and ...



..the second opening is into the smaller section where we keep the items we need to get to daily.

We used it about 3 months and love it and so far it seems to be using under 20 amp-hrs/day. I'll know more when we return and I put an hour/meter on it.

The complete build plus other galley mods are all at this link....

Endeavour 37 Interion Mods Index

Good luck,

Sum

[mbianka]

Sumner:

Very nice install!

[onestepcsy37]

i installed an adler barbour fridge/freezer and am very happy with it. but that doesn't mean you need to. depends on what use you expect to make of it. if it's just casual, ice or a 12 volt cooler might be best. worst, i think, is trying to use a 'college dorm' size 120 volt fridge, but one of the posters here is an engineer and she swears by hers...

[Mr B]

Waeko or Dometic, check out what they have to offer, Prices arent too bad either,
Its better than building your own, Gas, electric, 12 volt, 3 way,

[Richard Kollmann]

There are maybe 100 options to pick from when selecting refrigeration for a pleasure boat. Icebox conversion refrigeration systems are generally more of a challenge to select and install as you must do your own engineering. Cabinet self contained refrigerators are designed mainly for the RV industry so process heat removal is a problem. Portable refrigerators like Engel, Norcold, WAECO or Dometic are the simplest to install but usually are smaller than three and one half cu ft. There are key questions you must answer first before selecting a refrigerator system for your boat:
• What level of refrigerator temperature are you looking for inside refrigerator?
• Are you planning on cruising for extended time in a warm climate?
• Power management, will your boat’s DC power grid support an additional 35, 50,75, or 100 amp-hr per day requirement for 12 volt refrigeration?
• Refrigeration systems for small boxes are less expensive, what size box do you think you need?
• Do you want a freezing compartment?
R value of box insulation needed will depend on how you answer the above questions. Under certain conditions like box used as a drink cooler in cool climates an insulation value of R 10 may be adequate. For standard refrigerator temperature above Latitude 26N insulation R 20 is good. In tropical climates R 30 insulation is recommended. The greatest energy demand on refrigeration in warm weather is not lack of insulation it is the consumption by crew of cold drinks.

[sailorchic34]

Just for fun I calculated that cooling a 6 pack of beer / soda takes about 240 btu's to cool (40 degrees F delta) which when factoring in motor efficiency, etc. is ballparkish 100 watts, It takes 70 watts for direct conversion, but adding motor efficiency losses it comes in at about 100 watts or about 7.5 amps @ 13V for one 6 pack.

All the of 12v systems, other then Engel, pretty much use the danfoss compressor. The basic 12V compressor design is pretty much the same as the 120V compressors used in small dorm fridges, with perhaps a slightly smaller capacity in the danfoss unit.

The thing is that a BTU is a BTU weather the compressor is 12V, 24V 120V or 240V. So for a given amount of heat gain, its going to take roughly the same amount of amp hours.

I can tell you from personal experience that the 120V dorm fridge uses about the same amount of power as a 12V AB system. My daily power usage works out to 55-60 amps for refrigeration (less in winter). While an inverter adds a 10% loss to the 120V system, we must remember that the danfoss black box is also a DC/AC inverter and that there is a efficiency loss in that block box too.

I should note that the 120V compressor pulls a lot more amps when running at about 14 amps when running. But the duty cycle for the 120V fridge is 16 percent at 88-90 degrees F cabin temperature. This is for a 3.5 CF magic chef unit ($140) That works out to about 2.5 amps per hour, including inverter losses. This is about the same as the typical AB 12V system...

Of course, box insulation and condenser design/location can lower energy costs some.

[S/V Alchemy]

Now, that's math I can use.

It's just a baseline, however, because the skill of the OP in constructing or reinsulating a new box, the quality of the installation, ambient temperatures and frequency of access are all going to skew those numbers.

All I can say about the C&C original icebox is that it probably is surrounded by crumbling urea foam from the '80s or earlier and is just about useless.

I am moving toward a two-part solution: I already have a well-insulated, moderately efficient Nova Kool set-up for a medium-sized top-loading fridge box. I think the key is getting the frequently accessed items away from the breakfast/dinner/frozen foods. So I'm thinking that a Waeco or Engel unit in the pilothouse can contain cold drinks, whereas the "food box" is opened maybe twice a day (planning and note-keeping helps here, meaning fewer amps are going to be used with the bigger unit.

Whether the OP wants to go to this trouble or effort is unknown, of course! On my smaller boat, I just bring a Peltier-type 12 V cooler and wrap it in a "space blanket" after loading it with frozen and fresh items. Works for 24 hours, then you plug it into a 12 VDC for two hours. Repeat as needed or until you hit shore power.

I recommend Sumner's site, by the way. There are lots of sensible ideas and projects there.

[Richard Kollmann]

Sailorchic 34,
I do not rule out dorm 110 volt refrigerators, there are applications where they are the best choice for boats that take only short cruises and spend most of the year connected to shore power. I can not see why your daily amp-hrs are so high with a three and a half cu ft box in San Francisco. The US climate zone average temperature report shows average temperature of 57 degrees F in 2012 and only one day did temperature reach 90 degrees. It is true that an increase ambient temperature of 90 degrees over 57 average degrees would double daily amp-hours consumed.

It is better to use watts of power into compressor to watts of energy out (Btu) when comparing Coefficient Of Performance (COP) than heat loss projections. The major difference between your 110 volt unit’s inefficiencies could be comparing a 110 volt inductance compressor motor against a three phase variable speed 12 volt compressor. Danfoss BD compressors can produce COP figures of 2.84 in a small drink cooler box when operated at 2000 Rpm. This higher COP is why box’s smaller than 4 cu ft operated in cool climates can consume 50% less daily amp-hrs than older Danfoss BD compressors.

[Cheechako]

If the location is good, then just installing a simple compressor/evaporator unit is easy and works quite well.

[Pelagic]

Originally Posted by S/V Alchemy

....I am moving toward a two-part solution: I already have a well-insulated, moderately efficient Nova Kool set-up for a medium-sized top-loading fridge box. I think the key is getting the frequently accessed items away from the breakfast/dinner/frozen foods. So I'm thinking that a Waeco or Engel unit in the pilothouse can contain cold drinks, whereas the "food box" is opened maybe twice a day (planning and note-keeping helps here, meaning fewer amps are going to be used with the bigger unit.

I recommend Sumner's site, by the way. There are lots of sensible ideas and projects there.

Thanks all….. I am right in the middle of researching how to replace my aging units in the most energy efficient manner. . I agree with sailorchic34 that “box insulation and condenser design/location can lower energy costs some” ……but will Alchemy’s idea to modularize actually be more efficient or simply more convenient? That I don’t know
Are 2 small units more efficient than one big one?
I have in my pilothouse 2 old 24v ISOTHERM Top Loaded Fridge/Freezer boxes.
http://www.marinewarehouse.net/image...ed/TB50USA.pdf
They are mounted on top of each other with the bottom one used as a Freezer (it slides out) and the top for fluids. In replacing those 2 failing units I am actually wondering if a single, well designed and fitted unit, would be more energy efficient?

Could someone please post the Sumner's Link?

[Cheechako]

I contemplated two units at one time, but every scenario I came up with said that would use more electricity. I really liked the units I had that had top and bottom doors. Kept the drinks in the bottom....

[Shanaly]

Cheechako - where do I find a cheap compressor? - they re a multiple price of a fridge on oz ebay!
J

[Shanaly]

any compressor needs a good airflow - do i have to install a duct and fan?

[Shanaly]

Alchemy - can you post details of peltier arrangement? I have plates, sinks, and power supply, and no reliable info source for sizing/matching and installation
J