Reply
 
Thread Tools Display Modes
 
Old 10-11-2011, 08:50 AM   #1
Senior Member
 
belizebill's Avatar
 
City: Caye Caulker
Country: Belize, Central America
Vessel Name: Irish Miss
Vessel Model: 36' Marine Trader, D C
Join Date: Nov 2010
Posts: 227
On Board Refrigeration

I want to replace the 110 V college dorm type fridge on my boat. I have been looking at 12V and 12v/110 V. How do thease dual volt fridgs work? Are there two plugs. How would they be wired if only one plug in ? Im pretty sure my 12 and 110 systems are seperate?? How would the unit switch from the different voltage as needed? BB
__________________
Advertisement

belizebill is offline   Reply With Quote
Old 10-11-2011, 10:21 AM   #2
Guru
 
Conrad's Avatar
 
City: Calgary
Country: Canada
Vessel Name: Blue Sky
Vessel Model: Nordic Tugs 42 Hull #001
Join Date: Oct 2007
Posts: 1,553
RE: On Board Refrigeration

We have a NovaKool (R4500 I think) with the 12V/110V setup; it does require two plugs, one for each voltage. I kind of forget, but I think the 12V is hardwired while the 110 is an actual plug.

The switching is completely automatic at the fridge, i.e., when shorepower is connected it runs on 110V but once disconnected it switches over to 12V.

I believe there are discussions elsewhere on the forum about whether it's better to have a a straight 12V & use the shorepower to keep the batteries topped up vs straight 110V & use an inverter vs the dual voltage. (Assuming no generator.)

My vote is for the dual voltage.
__________________

Conrad is offline   Reply With Quote
Old 10-11-2011, 11:39 AM   #3
Guru
 
Capn Chuck's Avatar
 
Join Date: Jan 2009
Posts: 899
RE: On Board Refrigeration

Bill, I would suggest you go with straight 12 volt. The 110/12 volt systems just step down the 110 to 12. Here is our chaioce and we are very happy with it.
http://trawler-beach-house.blogspot....igerators.html

Chuck
Capn Chuck is offline   Reply With Quote
Old 10-11-2011, 11:47 AM   #4
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
On Board Refrigeration

Manufacturers do things differently but I believe the most common way of powering an AC/DC refrigerator is to power the compressor with AC and have a small inverter as part of the refrigerator's mechanism to convert battery power to AC when the refrigerator is "run" on DC.* This, I believe, is how our Norcold works.* However I may have that wrong and it may be that more units use a DC compressor and use a small transformer to convert AC to DC.

Our boat has a Norcold AC/DC unit the previous owner installed the year before we bought the boat (so it's 13 years old now). There is a breaker for the refrigerator on the DC panel and one on the AC panel. We switch over between batteries and groundpower with the breakers, but if one leaves both breakers on, the refrigerator will default to AC power if there is AC power available.

When we thought we had a failing refrigerator about three years ago we went shopping for a replacement. We wanted to retain the AC/DC capability as for us we feel this offers advantages over either a straight DC or straight AC unit..* We also wanted it to fit as closely as possible in the space occupied by the Norcold, and we wanted it to have a Danfoss compressor which everyone I've talked to with knowledge on this subject says is the best compressor for this type of refrigerator out there.

In the end we settled on a stainless steel Isotherm unit. Changing the refrigerator is a big job on our boat--- it has to enter and leave the boat via the front window which has to be disconnected from its fittings. When the Norcold "revived" itself we decided to keep it until it truly died, so we have not yet changed it out. But if or when the day comes that we do, we will go with an Isotherm unit unless by then there is something better out there.


-- Edited by Marin on Tuesday 11th of October 2011 11:50:55 AM
Marin is offline   Reply With Quote
Old 10-11-2011, 07:48 PM   #5
Senior Member
 
Jay N's Avatar
 
City: Edmonds, WA
Country: USA
Vessel Name: WESTERLY
Vessel Model: 1974 Pacific Trawler 37
Join Date: Oct 2007
Posts: 387
RE: On Board Refrigeration

Our*AC/DC Norcold went 25 years, and then it was still going.* But, we were heading for a 4 month adventure the next year, and didn't want to have to deal with possible failure.

After installing a custom size box (because Norcold/industry stopped making our size), we went with a 12VDC only*compressor.* Because the compressor was installed in the bilge instead of hanging off the back of the box, we gained 33% reefer space and 100% freezer space in the same physical box dimensions.

As best I can tell, our electrical usage decreased by at least 33% because of a more efficient compressor, and cooler operating location.

These are all good reasons to think about upgrading.
Jay N is offline   Reply With Quote
Old 10-11-2011, 08:06 PM   #6
Senior Member
 
Datenight's Avatar
 
City: Noank, CT
Country: USA
Vessel Name: Datenight
Join Date: Jan 2008
Posts: 415
RE: On Board Refrigeration

As mentioned in previous posts, we went with a 12v DC Isotherm with a remote Danfoss when the Norcold died. We also saw a reduction of at least 33% in amps per day. Would go the same route again.

Rob

37' Sedan

*
Datenight is offline   Reply With Quote
Old 10-12-2011, 04:24 AM   #7
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,537
RE: On Board Refrigeration

"As mentioned in previous posts, we went with a 12v DC Isotherm with a remote Danfoss when the Norcold died. We also saw a reduction of at least 33% in amps per day. Would go the same route again."


YES YES YES, the alternate energy folks DO have 12v units that are efficient , better compressor and expensive ,thicker insulation and door seals.

The RV stuff may work in 2 voltages , bur they were never constructed for efficiency.

Look at a Sun Frost IF you need house sized , as well as efficient.
FF is online now   Reply With Quote
Old 10-12-2011, 06:04 AM   #8
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
RE: On Board Refrigeration

Quote:
belizebill wrote:
I want to replace the 110 V college dorm type fridge on my boat. I have been looking at 12V and 12v/110 V. How do thease dual volt fridgs work? Are there two plugs. How would they be wired if only one plug in ? Im pretty sure my 12 and 110 systems are seperate?? How would the unit switch from the different voltage as needed? BB

With all due respect, from your post, I don't think you're ready to be doing electrical work on a boat.

Yes, your 12 and 110 systems are seperate.* There are not two plugs, there is a plug for 120 volt AC power but the 12 volt DCpower is usually hard wired.* The refrigerator has a circuit that checks for 120 volt AC power If it's there, the refrigerator runs on 120 volts AC.* If it's not, the refrigerator switches to 12 volts DC.. This is all automatic.
*
rwidman is offline   Reply With Quote
Old 10-12-2011, 06:11 AM   #9
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,377
RE: On Board Refrigeration

Check the archives, this subject has been BSed to death. The 12V/110V or 12V units from Nova Kool with Danfoss compressor are the same insulated refrigerator and either works just fine. What does most units in is inadequate air circulation - it happened to me 3 years ago.
sunchaser is online now   Reply With Quote
Old 10-13-2011, 01:54 PM   #10
Guru
 
skipperdude's Avatar
 
City: Whittier AK
Country: USA
Vessel Name: Apache II
Vessel Model: 1974 Donald Jones
Join Date: Oct 2007
Posts: 3,147
RE: On Board Refrigeration

The frige has a built in Inverter. I know because I tried to repair* my old frige.

When you plug in you have 110 when you un plug it automaticly turns on the inverter.

SD
skipperdude is offline   Reply With Quote
Old 10-14-2011, 04:20 AM   #11
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,537
RE: On Board Refrigeration

The most efficient fridges will use pulsed DC with a brain that attempts to slow the unit \to extend the run time as the brain learns.

The "most efficient" (in terms of cold vs amps used) would be operating , slowly , 24/7.

But too many owners would panic , so the mfg will only allow a 50 min run time.

Vacume plate insulation is great , but really expensive.

Even high quality insulation needs to be 2 fridge ,3 freezer inches thick , which cuts down on interior volume.
FF is online now   Reply With Quote
Old 10-14-2011, 12:36 PM   #12
Senior Member
 
belizebill's Avatar
 
City: Caye Caulker
Country: Belize, Central America
Vessel Name: Irish Miss
Vessel Model: 36' Marine Trader, D C
Join Date: Nov 2010
Posts: 227
RE: On Board Refrigeration

OK, I bought the Isotherm 12volt with the ASU system with enternal cold plate. Also a Isotherm Freezer 110 volt for the long trips. BB
belizebill is offline   Reply With Quote
Old 10-14-2011, 02:55 PM   #13
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
RE: On Board Refrigeration

Quote:
superdiver wrote:rwidman wrote:belizebill wrote:
I want to replace the 110 V college dorm type fridge on my boat. I have been looking at 12V and 12v/110 V. How do thease dual volt fridgs work? Are there two plugs. How would they be wired if only one plug in ? Im pretty sure my 12 and 110 systems are seperate?? How would the unit switch from the different voltage as needed? BB

With all due respect, from your post, I don't think you're ready to be doing electrical work on a boat.

Yes, your 12 and 110 systems are seperate.* There are not two plugs, there is a plug for 120 volt AC power but the 12 volt DCpower is usually hard wired.* The refrigerator has a circuit that checks for 120 volt AC power If it's there, the refrigerator runs on 120 volts AC.* If it's not, the refrigerator switches to 12 volts DC.. This is all automatic.
*

*I disagree, i think he needs to do it himself for sure, and learn.* I would have asked almost the exact same question 2 years ago.* After redoing the electrical on my boat I now have enough knowledge to be truly dangerous, but at least I have learned....* if he is anything like me us answering his question might only soak in a bit, having to figure it out as he goes with guidence from others teaches him for LIFE!

Here's part of the OP's post:

"Im pretty sure my 12 and 110 systems are seperate?? "

Think back to when you went to school.* They made you finish the first grade, then you were prepared for the second grade.*Only when you passed the second grade did they allow you into the third grade.* It continued like this until you graduated and were deemed "educated".

The OP needs to know a lot more about boat electrical wiring before he starts doing it himself.* Learning by making mistakes is not efficient and it could be deadly.

There are books available if he wants to learn but it's best to know what you're doing before you tackle and actual boat.

*

*
rwidman is offline   Reply With Quote
Old 10-14-2011, 03:19 PM   #14
Senior Member
 
belizebill's Avatar
 
City: Caye Caulker
Country: Belize, Central America
Vessel Name: Irish Miss
Vessel Model: 36' Marine Trader, D C
Join Date: Nov 2010
Posts: 227
On Board Refrigeration

Actually The Question about the two systems was rhetorical. Of course they are separate.I have never dealt with a AC/DC unit and did not know how they will be wired. Granted electrical is on the bottom of all my expertise and I too,know enough to be dangerous. Everybody off the boat, Im changing a bulb! BB****** Live like you are going to die tomorrow, LEARN like you will live forever-Gandhi


-- Edited by belizebill on Friday 14th of October 2011 03:22:27 PM
belizebill is offline   Reply With Quote
Old 11-05-2011, 08:48 PM   #15
Guru
 
C lectric's Avatar
 
City: Somewhere
Country: , Canada
Vessel Name: Island Pride
Vessel Model: Palmer sedan 32'
Join Date: Oct 2007
Posts: 1,874
On Board Refrigeration

Sunchaser's comment about air circulation is dead on.

If the compressor can't efficiently get rid of the heat it has removed from the fridge box then it can't cool and will run and run and run. Won't matter that the Danfoss unit is more efficient than the Novacool (oops Norcold) unit.

The Novacools have or can have a 12vdc output to run a muffin or computer fan and it will make a big difference to the cyle time and overall operation of the fridge when used to run the fan to exhaust the fridge cavity.




-- Edited by C lectric on Tuesday 8th of November 2011 07:58:59 PM
C lectric is offline   Reply With Quote
Old 11-06-2011, 06:49 AM   #16
Senior Member
 
belizebill's Avatar
 
City: Caye Caulker
Country: Belize, Central America
Vessel Name: Irish Miss
Vessel Model: 36' Marine Trader, D C
Join Date: Nov 2010
Posts: 227
RE: On Board Refrigeration

Ive ordered some SS louvered vents and a small fan. It should help. Going to redo the gally,so while everything is apart, it should be an easier job. Thanks for the inputs. BB
belizebill is offline   Reply With Quote
Old 11-27-2011, 09:22 PM   #17
Hospitality Officer
 
Andy G's Avatar
 
City: Pittwater
Country: Australia
Vessel Name: Sarawana
Vessel Model: IG 36 Quad Cabin
Join Date: Sep 2010
Posts: 1,557
RE: On Board Refrigeration

Does any one still use the Eutectic systems that came standard with a lot of the boats. They were wired up to engine.

When we bought our present boat the PO had kept the eutectic system and ran it soley from the new generator he had installed.*The boat is set up with a traditional underbench fridge*with*a large underseat*(saloon) freezer.Both have big Eutectic plates. The compresser*lives in the engine room and is raw water cooled.

It works well, however with the unit *siting in that enviorment in summer, with the long refridgerent*runs from the compressor to the eutectic plates, all runing through the engine room, must be very inefficient.
Andy G is offline   Reply With Quote
Old 11-28-2011, 03:56 AM   #18
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,537
RE: On Board Refrigeration

Eutetic plated are usually sized for the number of hours that power will not be aviliable.

On power boats that's 12 -14 hours between noisemaker operation to sleep at night.

Sailors will usually prefer 1 to 4 days of eutetic operation , but that required a LARGE (usually engine driven) compressor and the plate volume takes away lots of room from inside the fridge or freezer.

Hundreds of pounds of batteries today make DC possible for days , and do not require room in the fridge.

BUT seldom can the be recharged in the low time (usually under 2 hours) of a mechanical system.

Lived with all them ,and worked for a while for Adler Barbour, and today Propane is my solution
FF is online now   Reply With Quote
Old 11-28-2011, 06:04 AM   #19
Guru
 
Keith's Avatar
 
Vessel Name: Anastasia III
Vessel Model: Krogen 42
Join Date: Oct 2007
Posts: 2,716
RE: On Board Refrigeration

I have a Rich*Beers system with two plates in the freezer, run off a 110v compressor. Great system. Once went 48 hours without power or opening, and the temp was 31F when I got the power back.
Keith is offline   Reply With Quote
Old 11-28-2011, 03:23 PM   #20
Guru
 
City: North Charleston, SC
Country: USA
Join Date: Sep 2010
Posts: 4,390
RE: On Board Refrigeration

I've seen refrigeration systems that use seawater and a heat exchanger much like the typical boat air conditioning systems. I've seen them in catalogs, not actually installed in boats. It seems that would be more efficient than just dumping hot air into the cabin (or more typically, behind the cabinets).
__________________

rwidman is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
PC's on Board KJ General Discussion 9 04-19-2011 12:00 AM
Refrigeration.... the topic makes me HOT! hollywood8118 Other Trawler Systems 2 06-28-2010 04:42 AM
Refrigeration problem - any ideas? carvendive General Maintenance 5 07-20-2009 09:28 AM




All times are GMT -5. The time now is 07:48 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012