The perfect fridge ! Under Nav Station

[Susie Johnson]

Ted,

Thanks for all you help.  The price of the Norcold is very pricy$$$$.  We found the Kenmore for a cool cost of $119.00 compared to $700 to $1,000 for a Norcold.  We have an inverter on board so we can run the fridge on the water too.

The Kenmore is newly installed as of yesterday 7/20/03.  We'll see how it works.  Hopefully it will be good for the 3-4 months we can use our boat in the cold Midwest!

[Stu Jackson]

Inverter Use for Fridge

Susie

I sure hope you did an energy budget, and have an appropriately sized house bank to run your AC fridge off your inverter, and have included the inefficiencies of transferring DC back to AC.  The Norcold is a model that runs on DC unless AC is present.

Stu

[Ted Pounds]

According to literature on the Norcold it's actually AC driven and to run off DC it has its own small, built-in, inverter.  So using the boat's inverter should be OK.  The Norcold draws about 3 amps when running so you can compare that to the added draw for your inverter when the Kenmore is running.   :cool:

Ted

[Paul Blumenfeld]

Susie and Ted,

I'd like to get an update on how your refrigerators are working.  I'm trying to decide between putting in an Adler Barbour Cold Machine or something like the Norcold 323T.  I like the idea of the 110v while at dock.  Any suggetions from your experience?

[Ted Pounds]

Paul,

I've been happy with my Norcold.  (I didn't install it, by the way, the PO put it in).  The plusses and minuses as I see them are:

Plus:  uses 'wasted' space under nav table
 :)    runs off A/C at dock
       frees up the ice box for use as a nice, big dry locker
       easy installation - just stick the unit in and hook up the wires

Minus: not very efficient - only about 2+ inches of insulation and no way to add more
     can be a hassle to access when under way especially on port tack.
       opening the door dumps all the cold air (and some times the contents - see above)
       Not as much space as the ice box - I usually carry an extra cooler on long trips

If you have any more specific questions let me know.

Ted

[Stu Jackson]

REFRIGERATION

Paul, you wrote: "I like the idea of the 110v while at dock."

Seems to me that a 12 V DC system would work just as well at the dock, since your battery charger would more than make up for the current draw by the fridge.

What am I missing?

Stu

[Paul Blumenfeld]

Stu,

I have an 8D and two Group 27 batteries in series so I'm shouldn't have a problem. I've just read various opinions about running off the battery/charger while at dock.  I use the boat mostly for day cruises coming home at night.  85% of the time I'll have 110v at night and seems to be about a $1k price difference.

[Paul Blumenfeld]

Ted,

Thanks for the info.  What size batteries do you have and any problem running them down?

[Ted Pounds]

Paul,

I have two banks of golf cart batteries (I'm adding a starter battery this winter).  Like you I mainly day cruise.  Even when we travel overnight we end up at a dock as there a few anchorages on Lake Michigan.  So I have not had a problem with draining the batteries.  The reason I'm adding a starter battery is so I can keep the two house banks in parallel  so they can share the load which is less stressful on the batteries.  Since the Norcold draws 3 amps even constant running for two days uses less than 150 amp hours.  And that, by itself, would be OK for any bank with over 300 amp hours capacity ( max 50% discharge is usually the rule of thumb for decent battery life).  

Ted

[Stu Jackson]

Fridge Pictures

Do Larry's pictures seem the same as your installations?

See:  http://www.c34.org/projects/projects-refrigeration-2.html

Stu

[Ted Pounds]

Mine is similar, but my Norcold is tucked all the way under the nav table. It doesn't stick out like Larry's.

Ted

[Mike and Theresa Vaccaro]

Another option is a Norcold AC/DC unit that uses an evaporator in your icebox.  This is similar to DC units (Adler Barbour, etc), but has the advantage of using AC power when available.  

We've got an older (early 90's vintage) unit that we've kept running by replacing the power supply and thermostat unit.  We learned that the bulletproof Danfoss compressor actually runs on 24v AC power--thus the power supply either converts 110v AC or 12v DC to 24v AC.  Turns out that the "conversion" from 110v AC is much more efficient, which translates to more efficient cycle times.  This is similar to any "inverter" which is a convenient, but not efficient (i.e., some amp capacity is spent in the conversion process), way to produce AC power on board.  

Most air cooled units are challenged by a tropical environment (they've got to pump the heat out of the ice box and recirculate it to the ambient atmosphere).  The higher the ambient temperature, the less efficient the radiator.  A small 12v "pan" fan (similar or identical to the one mounted on a computer) goes a long way to improving efficiency of the radiator.  Installing another small fan in the ice box itself will also improve efficiency by circulating cool air throughout the deep box.  The reduction in cycle time usually offsets the small amount of electricity used by these fans.

Cruising World just did a great article explaining refrigeration options.  Newer units are also much more efficient than the older ones, so there is probably some merit in "replace" vs. "repair," depending on circumstances.

The AC/DC Norcold unit is available from West Marine for about six boat units.  It comes with an L-shaped evaporator that is easy to install in a Catalina 34 icebox and takes up very little room.  With this type of evaporator, you do lose the "small freezer" provided by a continuous rectilinier type, however.

Another useful technique is to use ice, dry ice or ice packs in the icebox to supplement the electrical system.  This will also reduce cycle time and power consumption and can be very efficient for over-night and weekend trips away from an AC power source.

Since refrigeration is usually the number one  gobbler of DC power on board, it's worth thinking about your needs/desires and installing an appropriate system.  Sometimes, the domino effect catches up with you and the size of your house bank becomes a limitation!  

Incidentally, Danfoss (an English company) has a great website, including tech manuals and troubleshooting documentation.  The compressor itself is "hermetically" sealed and thus, maintenance free--it either works or it doesn't!  If you're not familiar with servicing refrigeration units, probably best to leave that to someone with the proper equipment and knowledge, but most small units can be installed by anyone, since the lines come pre-charged from factory.  A properly installed system is usually a lot like the fridge in your kitchen--runs forever (or at least as long as most of use typically own a particular boat!).  Six cubic feet of cold beer is a worthy goal...

More stuff we've learned the hard way!

Cheers,

Mike

[Steve Michel]

Sorry Folks!
My e-mail address is michelsecurity@erols.com