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Crotchety Old Member
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Discussion Starter · #1 ·
We have a problem that I'm trying to solve.

We are purchasing a Morgan 41 OI from someone that was a liveaboard. They tore out the cabinet that housed the refrigerator, and put in a standard apartment-sized refrigerator (I know, I know). Our ideas are that we are going to rebuild the interior and bring her back from the throws of what was done to her.

That said, I am working on a design for a freezer/refrigerator that is more traditional for the boating world. A top-loading design. There is a dry box that we are going to convert to a freezer using a cold plate. It is probably about three cubic feet. I then want to build a bigger box next to it, and channel some of the cold, via PVC pipe, to the bigger box. The PVC pipe will be around three inches in diameter and will have a vent so I can control the amount of cold channeled to the refrigerator side. Once completed, all will be heavily insulated.

Because there is no refrigerator box, I have been looking endlessly for something that I can use, as opposed to building one. I came across a laundry sink at Home Depot, that is square and has approximately 10 square feet of space. This looks like it could be ideal, if insulated properly.

Have any of you looked into this? I'm looking for any ideas on this. Thanks!
 

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Over Hill Sailing Club
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When I renovated the fridge, I thought about fitting in a standard cooler but there wasn't one that would fit the space. I just relined and reduced the space to the required size with 2" polyisocyanurate and then glassed that over for a permanent surface. The most important thing to me was making it super insulated so that the new little Isotherm SP unit would work at maximum efficiency. If sitting at a dock, there is no issue but out cruising, watt/hours are the main consideration.
 

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islander bahama 24
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I have installed the Engle units and technautics system and I found that watt for watt the technautics holding plate system is more energy efficient however you would have to build the box for it as upposed to the little Engle unit drop ins others are recommending if over 5 cubic feet of refer and a couple cubes of freezer I would personally recommend a holding plate system about quite a bit higher cost
 

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Crotchety Old Member
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Discussion Starter · #6 ·
Thanks, all.

I did the research on the Engel, and I really like the idea. The problem is that they are a bit small. We will need something larger - more like 7-10 square feet. That is why I'm leaning towards a design using the Cool Plate cold plate system. I can size the plate that comes with the system so that I can make it much larger, if I want.

I didn't mention this, but the plan is to sail her on an extended voyage into the south Pacific.
 

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Thanks, all.

I did the research on the Engel, and I really like the idea. The problem is that they are a bit small. We will need something larger - more like 7-10 square feet. That is why I'm leaning towards a design using the Cool Plate cold plate system. I can size the plate that comes with the system so that I can make it much larger, if I want.

I didn't mention this, but the plan is to sail her on an extended voyage into the south Pacific.
One of the problems that we saw with holding plate systems is the attention they require over what the Engel unit needs. At one point we had an emergency back home that required us to fly back ASAP. If we had a holding plate system it would have delayed our departure by a day. That MAY not be a problem, but it is something to think about. ;)

I built in one Norcold unit back in 2002 (Guenevere's Projects, Ice box replacement ). The Engel does much better and I have since taken out the old unit, built a shelf and put in an Engel chest type on it. If I had the room, I would use 2 units, one for a freezer and one for a reefer. And because each Engel can do either, that way I would always have a backup.

Another plus, at least for me, is that when the next units come out that only use half the power, I can just toss the old one without a LOT of building on the boat! :D

Greg
 

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islander bahama 24
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One of the problems that we saw with holding plate systems is the attention they require over what the Engel unit needs. At one point we had an emergency back home that required us to fly back ASAP. If we had a holding plate system it would have delayed our departure by a day. That MAY not be a problem, but it is something to think about. ;)

Greg
Greg please explain to me why the holding plate system would have delayed your emergency departure from the vessel we just put one in dads boat
 

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Greg please explain to me why the holding plate system would have delayed your emergency departure from the vessel we just put one in dads boat
All of the holding plate systems that we saw as we cruised (for about 5 years) were engine driven. So, if you did not start the engine every couple of days, the system would quit. So we would have had to dump the contents of our fridge. It may be different now.

Also, when I was deciding on a system, I saw that unless a small fan was put in the box, the cycling of the holding plate caused some large temp graduations in the box over time.

Like I said, this may be different now.

Greg
 

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Crotchety Old Member
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Discussion Starter · #10 ·
All of the holding plate systems that we saw as we cruised (for about 5 years) were engine driven. So, if you did not start the engine every couple of days, the system would quit. So we would have had to dump the contents of our fridge. It may be different now.

Also, when I was deciding on a system, I saw that unless a small fan was put in the box, the cycling of the holding plate caused some large temp graduations in the box over time.

Like I said, this may be different now.

Greg
Good things to keep in mind. Before we did the Norcold on the Columbia, we had an engine-driven cold plate system. I did not want that system because I didn't want to have to start the diesel to freeze the plate.

We're looking at an electric-driven cold plate.
 

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I was JUST looking at the holdover electric system, I can always learn ya know.:D

At any rate I was at a site at; Marine refrigeration for boats

It states;
" Engine/Alternator battery charging

The DC refrigeration system will drain your boats batteries, so check battery capacity and charging capacity. Many manufacturers recommend 500 amp hrs battery capacity for a refrigeration system in the tropics. Plus you will need charging ability, so make sure you have a large alternator say 100 amp. A large alternator to charge the battery bank in short order if you only use the engine in limited periods.

Solar and wind Battery charging

If you spend large amounts of time sailing, consider solar power, wind generators or water generators to charge your DC system. This will keep your batteries charged while not at the dock and will save you needing to run the engine.

The same applies for at anchor. While at anchor you don't want to have to run the engine. Some manufacturers like SeaFrost have systems for alternate energy.

Solar Stik has 2 50 watt panels and can put out up to 89 amp hours per day. This will not supply a large DC refrigeration system but will cut down the amps consumed."

Our Engel system (one box) is more than able to keep up in stateside temps with one 85 Watt solar panel, for our boat. I add about 100 more Watts for tropical temps.

Greg
 

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islander bahama 24
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All of the holding plate systems that we saw as we cruised (for about 5 years) were engine driven. So, if you did not start the engine every couple of days, the system would quit. So we would have had to dump the contents of our fridge. It may be different now.

Also, when I was deciding on a system, I saw that unless a small fan was put in the box, the cycling of the holding plate caused some large temp graduations in the box over time.

Like I said, this may be different now.

Greg
OK Greg that explained it very well and yes things have come a long way since them days the unit I just installed uses a standard Dan Foss d50 12 volt compressor and it uses about 12 to 15 ah per day to maintain 15 to 20 deg f in freezer and 38 deg in fridge ( 2.5 cf freezer and 7 cf refer )
 

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OK Greg that explained it very well and yes things have come a long way since them days the unit I just installed uses a standard Dan Foss d50 12 volt compressor and it uses about 12 to 15 ah per day to maintain 15 to 20 deg f in freezer and 38 deg in fridge ( 2.5 cf freezer and 7 cf refer )
That, 12 to 15 Ah usage, is VERY impressive!!!

What is the outside ambient temps when you got that type of power usage? What is the measured Ah draw of the system when running?

Greg
 

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One of None
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500 ah..... eh, I think unless someone intentionally wants to go without engine charging.. yeah maybe you can run a week . but I think most can get by with more conservative battery banks. as most people do run the engine a couple hours a day anyway. More battery is always great but with the even more efficient systems these things can run on 200 ah a couple of days.

10 cu ft is not a large box! Also, Norcold and Engel use a different compressor that doesn't have high a starting draw like danfoss which, is still a very low draw and very efficient in it's own rite.

Holding plate systems are "ice storage" and don't require the system to run like the old open type engine driven systems that were large enough to cool a 8ft x 10 ft walk in box! "gotta run it to keep the seals lubricated" is also moot.

Oh.. as far as tropical... most people will give out faster then any R system 100 degrees ambient is still not a full load condition for most units either.
 

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That, 12 to 15 Ah usage, is VERY impressive!!!
I rarely bother to check facts but the performance of this unit begs investigation.

On the Danfoss UK website there are literally hundreds of spec sheets so I didn't do an exhaustive check but I did find a compressor designated BD50F which is the closest I could find.

Compact Classic - 2501

The spec sheet for a fridge using an evaporator discloses the current draw at 5.2 amps. So to achieve 15ah a day means that the compressor unit runs for a max of three hours a day. And that is on a box of 200 litres. The boxes quoted by Newhaul total 270 litres, a quarter of which is freezer. That's not impressive - that's mind-boggling.

I have a compressor that draws 4.7 amps while running and it is seen as pretty good for modern 12v refrigeration (similar to the one in the link above). I use about 32ah a day to keep the fridge at 6 degrees C. The unit runs a total of 7 hours a day. My insulation may not be "weapons grade" but it's not bad.

I discarded eutectic holding plates on a 110v compressor because they couldn't keep up - to now discover that there is a unit that uses half the current that my new fridge draws is nothing short of spooky.

One can only assume that you have extremely efficient insulation.
 

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I rarely bother to check facts but the performance of this unit begs investigation.

On the Danfoss UK website there are literally hundreds of spec sheets so I didn't do an exhaustive check but I did find a compressor designated BD50F which is the closest I could find.

Compact Classic - 2501

The spec sheet for a fridge using an evaporator discloses the current draw at 5.2 amps. So to achieve 15ah a day means that the compressor unit runs for a max of three hours a day. And that is on a box of 200 litres. The boxes quoted by Newhaul total 270 litres, a quarter of which is freezer. That's not impressive - that's mind-boggling.

I have a compressor that draws 4.7 amps while running and it is seen as pretty good for modern 12v refrigeration (similar to the one in the link above). I use about 32ah a day to keep the fridge at 6 degrees C. The unit runs a total of 7 hours a day. My insulation may not be "weapons grade" but it's not bad.

I discarded eutectic holding plates on a 110v compressor because they couldn't keep up - to now discover that there is a unit that uses half the current that my new fridge draws is nothing short of spooky.

One can only assume that you have extremely efficient insulation.
That was sort of my question.
If the outside air temp is low, then the compressor does not need to run as much. If super insulation is use, that to will cut down on run time. BUT, is $2K+ worth of insulation, above the system cost, worth it?

Our Engel unit draws 2.4 ~ 2.6 Ah starting, then throttles back to a lot less as it runs. You can see that in my short Youtube video at;

It shows the actual Ah draw on our meter. Our complete boat, with 300 Ah house bank ran on 4 each 32 Watt solar panels - - - IN the San Francisco Bay area. NOT SO IN THE TROPICS!!!

Also, what really takes the power draw is cycling water/drinks/food in and out of the box. I'm talking real life here, not test bed stuff. ;)

Greg
 

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islander bahama 24
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That, 12 to 15 Ah usage, is VERY impressive!!!

What is the outside ambient temps when you got that type of power usage? What is the measured Ah draw of the system when running?

Greg
Greg first all my temps are in ferinheight not centigrade now to answer you as best I can have only had the unit installed for about a month now and the ambient air temp in the engine room is about 50 deg f and outside air about the same and water temps in the low 50's with a cabin temp of about 65 deg f and 3 inches of closed cell foam insulation the unit is drawing about 3.5 amps when running and set for the temps we maintain in the freezer and spill down fridge ( front loading unit) spill vents are fully closed and the unit so far has been cycling on about every ten or so hrs with between 60 and 90 minute run times I will have more difinative info to share after next summers cruise to Alaska I will be keeping track of all the run time during that trip believe me I'm skeptical of the numbers as well but first hand reads tell the story
 

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Greg first all my temps are in ferinheight not centigrade now to answer you as best I can have only had the unit installed for about a month now and the ambient air temp in the engine room is about 50 deg f and outside air about the same and water temps in the low 50's with a cabin temp of about 65 deg f and 3 inches of closed cell foam insulation the unit is drawing about 3.5 amps when running and set for the temps we maintain in the freezer and spill down fridge ( front loading unit) spill vents are fully closed and the unit so far has been cycling on about every ten or so hrs with between 60 and 90 minute run times I will have more difinative info to share after next summers cruise to Alaska I will be keeping track of all the run time during that trip believe me I'm skeptical of the numbers as well but first hand reads tell the story
OK. Thanks for the come back.

I now understand. With the ambient temps around 50 F. About any system will be using around the low area of the power usage.

Good luck and I hope it all works out for ya. Using a reefer system in the US above the LA area is a very different animal than in a tropical zone. I know I was taken by surprise when we compared usage between the SF Bay area and the Sea of Cortez in the summer! :eek:

Greg
 

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islander bahama 24
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One thing I forgot to mentioned was that the compressor is switched to run at about
3/4 speed or just over 2500 rpm which results in approximately a 10% longer duty cycle however at about 2 amps lower draw it uses less ah per day according to the book it should use 3.8 amps my meter says 3.4 amps so real close to the tech specs for the unit and in these colder waters we get by with about an hour per ten to keep cold so that works to be somewhere in the stated ah range I fully expect that to triple in the tropics
 
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