Nova Kool? Dometic? Norcold?
- Thread starter Chris491
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RickB
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- Vessel Make
- CHB 48 Zodiac YL 4.2
A ball peen hammer is OK, just*align a large flat blade screwdriver between it and the evaporator.
*
Perhaps there are different kinds of AC/DC units. I have always been told that the AC/DC units are all AC, but they have inverter circuitry in them so they can run "on" DC. That's one of the things the repair shops who work on Norcold units--- or used to--- in the Seattle area told me they don't like about them. They apparently use a bizarro (their word) 20-volt or 24-volt AC motor.
JD
Guru
I have the manual for my Nova Cool here on the desk.* The only difference between the 12V model and the 120V / 12V models according to the wiring Schematic is in the dual voltage unit it has*a*power supply box*that is in the system that the 12V from the battery goes into and 120V from the shore power goes into*then 12V exits to the compressor control module.** All test procedures refer to 12V only at the control module.
Anyone that needs the manual I would be willing to FAX it to them it is eight pages.
*
RickB
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Nearly all the modern units use the Danfoss BD brushless DC compressors. These are variable speed permanent magnet rotor machines that use a fairly sophisticated commutation system that is in many ways identical to the power controls on diesel electric propulsion.
The motors are DC, the voltage into the motor on the Danfoss units varies from 27 to 45 VDC to control speed. There are three wires going into the motor so that might be why some people think it is an AC motor. That and the fact that that little box on the side of the compressor contains both a converter to turn AC into DC, and an inverter to*generate the DC pulses that drive the motor.
Unless the tech is stuck in the 60's there is nothing "bizarro" about the units. They are amazingly efficient compared to the older single speed machines.
*
-- Edited by RickB on Tuesday 15th of February 2011 09:05:57 AM
-- Edited by RickB on Tuesday 15th of February 2011 09:07:28 AM
Would this basic description apply to the Norcold AC/DC units too, or at least Norcolds from the late 90s?* It was the Norcold specifically that the service shops in this area didn't like because (among other reasons) of what they considered to be a very odd motor setup.
*
RickB
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The older Norcolds with the tall beancan*looking compressors were AC, about 20 volts if I recall correctly. They used a solenoid sort of vibrating slug compressor. It wasn't really a motor in that it didn't rotate.*
RickB
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*Yes, that little box on the side of the compressor has the ciruitry that converts AC to DC that is then sent along to a 6-pole IGBT (insulated gate bipolar transistor) inverter that sends carefully timed*pulses to the field of the permanent magnet motor that are phased to create a rotating magnetic field that turns the armature that drives the compressor that pumps the refrigerant that cools the beer.
The things are magic. They measure the back*EMF to determine the load and speed and make adjustments to the phase and timing of the pulses to manage the operation. they run from around 2000 rpm up to about 3500, 27 volts for low speed and linear up to 47 for full speed.*If you have one running on a 24 volt system that alway hangs around*27 volts it will never revert to AC operation ... funny little unintended effect*of the control circuit. I think Danfoss cleaned up on that design and their patents.
OP
OP
Chris491
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Well, I now have two months' time on my Nova Kool R4500 'fridge, and I'm pretty OK with it--not thrilled, but OK. It was the largest unit I could have in the space allotted in my 31- trawler. The freezer takes up more space than I would have liked, so there is limited space for tall bottles and cartons; I'm guessing those kinds of things will live in the ice chest inthe cockpit while cruising.
The folks at Long Beach Marine Refrigeration--about which I have nothing but good things to say--convinced me to install a DC-only unit, and so far I am glad I did. If I intend to use it while at anchor, however, I*will have to increase battery capacity or add solar panels or something as it runs the batteries down pretty quick: over a three-day weekend , the house batteries (four golf-cart batteries) ran down to about 25% in 36 hours before I plugged back in.
Which leads to my next question. There is a lovely-big crisper bin in the bottom of this unit. Could I put ice in that, either water ice or dry ice, and shut off the 'fridge when not under way? This seems sensible, but it also seems too easy a solution; on the other hand, it may be that this is exactly why there is such a big crisper bin in such a small 'fridge. Any experiences any of you have had using ice, either water ice or dry ice, to cool your DC refrigerators while at anchor would be deepley appreciated.
Chris Ericksen
Long Beach, CA
The folks at Long Beach Marine Refrigeration--about which I have nothing but good things to say--convinced me to install a DC-only unit, and so far I am glad I did. If I intend to use it while at anchor, however, I*will have to increase battery capacity or add solar panels or something as it runs the batteries down pretty quick: over a three-day weekend , the house batteries (four golf-cart batteries) ran down to about 25% in 36 hours before I plugged back in.
Which leads to my next question. There is a lovely-big crisper bin in the bottom of this unit. Could I put ice in that, either water ice or dry ice, and shut off the 'fridge when not under way? This seems sensible, but it also seems too easy a solution; on the other hand, it may be that this is exactly why there is such a big crisper bin in such a small 'fridge. Any experiences any of you have had using ice, either water ice or dry ice, to cool your DC refrigerators while at anchor would be deepley appreciated.
Chris Ericksen
Long Beach, CA
Edelweiss
Guru
The Novakools are made up in vancouver, BC. I got a walk through of the Plant. When I was looking to replace my Norcold, I gave them a hard look and liked them a lot, but the size I needed that would fit my built-in space was a strange layout, freezer on the bottom and a smaller fridg space, would have had to modify the space anyway! Norcold discontinued my size too, so I ended up settling for a used fridg pulled out of a 4788 Bayliner. Hopefully, it will last for a few years as I don't want to rebuild that enclosure. I have used ice in the crisper before and it will keep things like an ice chest. Just don't have any frost in the freezer or frozen liquids. It will melt and run everywhere!!
-- Edited by Edelweiss on Tuesday 30th of August 2011 01:51:53 PM
-- Edited by Edelweiss on Tuesday 30th of August 2011 08:54:42 PM
-- Edited by Edelweiss on Tuesday 30th of August 2011 01:51:53 PM
-- Edited by Edelweiss on Tuesday 30th of August 2011 08:54:42 PM
FF
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" All I have to do with my Nova Kool AC/DC refrigerator is turn it on and fill it up. A caveman could do it. "
And on anchor what is your endurance? How many days till dead batteries or the noise maker has to recharge ?
The best toss in units for many folks are the Sun Frost , big (thick insulation) and efficient , but not cheap.
And on anchor what is your endurance? How many days till dead batteries or the noise maker has to recharge ?
The best toss in units for many folks are the Sun Frost , big (thick insulation) and efficient , but not cheap.
Adelaide
Senior Member
We also have the Nova Kool DC only fridge. We do have a solar panel that assists with keeping the batteries charged and it works well.
*
-- Edited by Adelaide on Tuesday 6th of September 2011 05:57:26 PM
*
-- Edited by Adelaide on Tuesday 6th of September 2011 05:57:26 PM
FF
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The OFF GRID folks believe it is far better to not need energy than have to create it and save it.
Someone that loves the hook, and QUIET!
Toss the boat and RV catalogues and look in the alt energy suppliers.
Home Power mag is on line free , look at their advertisers to get efficient , not low cost refrigeration/freezers.
Someone that loves the hook, and QUIET!
Toss the boat and RV catalogues and look in the alt energy suppliers.
Home Power mag is on line free , look at their advertisers to get efficient , not low cost refrigeration/freezers.
FF
Guru
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www.sundanzer.com is one of the off grid units, that might be more efficient than boat or RV items.
