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Old 07-11-2011, 10:53   #31
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Re: Help with Refrigeration Decisions . . .

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Originally Posted by sailorchic34 View Post
Being Blonde I'm somewhat unconventional. I in my blondness went with a standard 120V fridge with an inverter, which everyone said would not work on the hook. Now being an engineer I know that a btu is a btu weather 12V or 120V. In other words the amount of heat rejection for a size box is the same weather the compressor runs at 12V, 120V, 240V or 4160V

So being Blonde and unconventional, I put a 3.5CF dorm fridge with a small freezer on my boat, bolted it down and put a latch on the door to hold it close when healed. Think it cost me $120 for the fridge and $40 ish for the 700 watt inverter. this was four years ago.

Now when running the fridge pulls 1.4 amps at 120V or 168 watts. Now wait before you say she does not know what shes talking about and oh lordy that's a lot of watts, let me continue.

Factoring in the efficiency of the inverter, I figure its costing me 10 percent more so call it 184 watts. yikes! Big load and it is. The trick is it runs about 2 minutes every 15 minutes in 75-80 degree weather, or .13 hours per hour. I'll round it up to .15 hours per hour as its not exactly two minutes

So take the 184 watts x .15 = 27.6 watts per hour or about 2.3 amps per hour or say roughly 60 amps a day. With door openings its probably more like 80 amps a day. Which is in the ballpark of the typical AB 12V system uses. The difference is the 12V compressor just runs longer..

Ok maybe its just the blonde way of doing things and your mileage may differ. but I just put that out there FYI.
I have no doubt your system will work as you claim in San Fran but I doubt you will see the same performance in the tropics. Also 80 amp hours per day is about double what I would be shooting for but this setup has many financially appealing attributes. I just cant imagine it would be well suited to use in the tropics.
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Old 07-11-2011, 11:01   #32
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Re: Help with Refrigeration Decisions . . .

I've always heard that you're not supposed to tilt conventional refrigerators because of how the oil sits in the compressor. Would a mono heeling often affect a normal "dorm fridge"?
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Old 07-11-2011, 11:25   #33
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Re: Help with Refrigeration Decisions . . .

Seems I read that the old Danfauss compressed units (cold machine etc) were 120V compressors and the Black box inverted the 12v. The newer Danfauss which came out several years ago are true 12v units. Is/was this correct?
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Old 07-11-2011, 11:55   #34
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Re: Help with Refrigeration Decisions . . .

I'm pretty sure the Danfoss compressor uses AC (not necessarily 120v) which it gets from the black box.

I'm sure that the dorm room stand alone units, at least the older ones, were not designed to conserve electricity. I looked at the new ones on Amazon--some had an energy rating--typically 325-350 kwh/yr. The Energy Star model I found claimed only 260 kwhr/yr, which would use about 66 amp-hrs/day at 12v with a 90% efficient inverter. However, these usage guides assume room temps of about 70 degrees, and the insulation on these units looks like a lot less than 3 inches.
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Old 07-11-2011, 12:24   #35
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Re: Help with Refrigeration Decisions . . .

Well I expect that because my compressor only runs for a few minutes at a time that even healed over 20-30 degrees, which I have been know to do, it does not worry it too much. Least wise not yet. I figure worst case if it only runs 5-6 years I can always get another pretty cheap. No way can I afford a $1000+ 12V system.

on insulation, yes looks like only an inch or a bit more of insulation. On mine the condenser is built in the two sides of the exterior panel. So insulation is a bit weak and can't really add more. If I did it over I'd look for one with a rear exterior condenser. Then insulation could be added to the exterior maybe...

Not saying its a great idea, only that for a rather poor sailor chic it works well enough for me.
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Old 07-11-2011, 20:33   #36
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Sailor chic I think it's brilliant and tip my hat to you for thinking outside the Nigel Calder indoctrinated west marine fueled world we operate in!
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Old 18-12-2011, 01:02   #37
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Re: Help with Refrigeration Decisions . . .

Same problem. No decisions. Had an engel it broke! Have you looked at the price of Engel machines. $1000 is wishful thinking. Seems that the Small DF makes are in the same ballpark
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Old 18-12-2011, 02:10   #38
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Re: Help with Refrigeration Decisions . . .

Avast! My Engel died the first day I got to Sumatra!! The compressor swing motor has a dead short in it, and it used heaps of power when the temp was 38C!!! Would not freeze, only cool. A low capacity unit.
Had a danfoss bd35 in the old boat, would freeze in 15 minutes and ran off of the 150 watt solar panels, no need to charge the batteries with the motor.

Going to put the bd50 and a small vertical freezer/evaporator in when I return to Langkawi, costs a lot, but it WORKS!!!! in the tropics and makes ice cubes and I can make ice cream when the surf drops?
Cheers from Keith.
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Old 18-12-2011, 14:01   #39
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Re: Help with Refrigeration Decisions . . .

As can be seen here in this thread there are as many suggestions based on the many variables and opinions. Here's my 2cents worth. 9 years ago when I purchased my 43' CC Ketch it had a Norcold upright refer which didn't work. I removed it and replaced it with cabinetry. Fortunately the boat also came with a large refer space meant to be used with block ice. I divided it into a refer/freezer and installed a water cooled Grunert holding plate system using a 110 volt compressor off a 3000 watt inverter. Here in the Pac. NW it worked adequately running 1 hour in the morning and 1 hour in the evening. And yes it’s potentially expensive power wise but the refer/freezer is a bit on the large size. The freezer and refer measures each 28” deep x 25” x 14”. In the summer time I would add another hour of operation. This last summer I bit the bullet and tore the whole unit out by cutting out the side wall (to preserve the counter tops) and reinsulated it with blue and pink insulation boards found at Home Depot. I first lined the space with heavy mil plastic sheeting then added 6 inches of floor insulation and 4 inches everywhere else. I lined it with pre-fabed FRP panels found at Home Depot and filleted the seams with a West System paste, the results were dramatic. Construction note; I used a Dremel plunge cutter tool using the dry wall cutting blade to cut the insulation board. The blade of course wasn’t deep enough to cut through the thickness of the insulation boards so I would make the cut on one side, use an ice pick to create a series of dots on the opposite side and then “followed the dots” for the final cut, very effective.
Where originally the freezer would only go down to 18 degrees it now holds pretty much at 10 below. There are times during an hour of operation where the compressor shuts down early because the temps have reached their operating parameters. I have no doubt when I reach the southern climates another hour or so of compressor time will be needed but for me it’s worth it.

My system uses a fair amount of power when running but ultimately it works out about the same as a Danfuass unit which cycles on for about 20 minutes every 15 minutes or so 24/7. I’ve heard good things about the 12 volt refer systems currently on the market. One solution to the question of water cooling and having to poke another hole in the hull is to mount the keel cooler in the fresh water tank. It solves the galvanic issues and when the boat needs to go on the hard the refer can keep operating.

The Engle refer is a viable one that seems to be a popular solution when the boat loses it’s refer in Mexico. It’s always a question though of where to put it.
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Old 22-12-2011, 14:37   #40
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Re: Help with Refrigeration Decisions . . .

I am going through the process of installing a fridge & freezer unit on our boat. I haven't really got much to add to this conversation that hasn't already been said, except to remind y'all that regardless of what system you use to generate the coldness, the amount of electrical energy that will be required to keep it cold is proprtional to the amount of heat energy your insulation lets in. i.e. the better your insulation, the less run-time for your cooling system. So don't focus too much on air cooled versus water cooled, cold plate versus eutectic, etc remember to give some careful thought to the type and thickness of your insulation (and to the need to prevent moisture ingress into that insulation).
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Old 22-12-2011, 15:16   #41
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Re: Help with Refrigeration Decisions . . .

I'm probably too scientific for this thread, but will give it a try anyway. Your insulation must meet the following four criteria to be really effective:

1. Block conductive heat transfer
2. Block convection heat transfer
3. Block radiation heat transfer
4. Block moisture and/or other contaminants from the insulation

Don't be too quick to click this away because it sounds more difficult than it is, for example, the radiation barrier can just be some aluminium foil with the shiny side outwards. Look up these terms or find them in the excellent dedicated refrigeration book from Nigel Calder and others.

Click the following photo to find my complete album of the rebuild we did.
(or click here for easy access: http://sv-jedi.smugmug.com/Projects/...16492663_CNnX6)



ciao!
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Old 22-12-2011, 16:03   #42
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Re: Help with Refrigeration Decisions . . .

So how do you cover/glass the tinfoil Nick?
And was there enough left over for a hat?
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Old 22-12-2011, 16:11   #43
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Re: Help with Refrigeration Decisions . . .

We have an Engel onboard for the last year that's been great (the 35). Super quiet, very low consumption, very cold even when packed to the gills. Like your set up we started with a Norcold in the icebox (which we learned why it's nicknamed the Notcold when we got into much warmer water). Mounting it is a bit of a pain in the ass; we're having our seaberth cut open to make space for it. Blasphemy, I know, but it's a great place for it.

One thing to consider as well is running two separate units. We don't really need a freezer (haven't had one for five years at this point), and although more space is always nice we've made it work including having a newborn onboard and needing to store milk and chilled medications. If we had the space I'd run two 35's so we can either run one as a freezer and another as a fridge, or both as fridges, or whatever.

If it dies it's money well spent. My friend just got to New Zealand (from San Diego) with a 45 unit; he loves it as well.
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Old 22-12-2011, 16:32   #44
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Re: Help with Refrigeration Decisions . . .

I was actually going to give these 12v units a run



Marine Fridge Freezer BCD-210 - Marine refrigerator
Which evakool Aust. sell
EvaKool Australia-BCD210L - $1477.00
for 3 x US retail price
Sun Electronics Upright Fridge/Freezer BCD-210 7.4 CF 12/24V [BC-210ID] - $575.00 :

Evakool also have these upright 12v freezers from, I am pretty sure, the same manufacturer

Evakool Store - TravelMate Deep Freeze 108

Also interesting to see that the manufacturer also do smaller units that look remarkably like a waeco


Portable Fridges BCD-60

WAECO CF-60AC VERB
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Old 22-12-2011, 17:41   #45
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Quote:
Originally Posted by cat man do
So how do you cover/glass the tinfoil Nick?
And was there enough left over for a hat?
There is an epoxy moisture barrier under the tin foil. I was too late pressing the foil into still tacky epoxy so I just used some 3M spray glue.

Man I got soo much foil for hats left! Now let me find an original pic this time...



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