refrigeration

Suggestions on keeping the cook happy
madaz
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Location: Hobart, Tasmania

refrigeration

Post by madaz » Thu Jun 28, 2007 3:59 am

is there any reason why i couldnt just use a normal smal fridge freezer unit with an inverter? apart from not being abel to run it of 12 V directly?

northerncat
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refrigeration

Post by northerncat » Thu Jun 28, 2007 4:18 am

inefficiency?? inverters run at 85% , also the insulation in a household fridge is not up to scratch for remote operations as fridge makers assume an abundance of 240v to keep the fridge cool, can buy a small freezer and reset the motor for a fridge then you get better insulation, this is the track i went down before i decided to build my own to sit under the table



sean

mahnamahna
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refrigeration

Post by mahnamahna » Fri Apr 02, 2010 9:29 pm

northerncat wrote:i have built my own and will be using an ozefridge setup, the fridgefreezer will live under the table the unit will run a top loading freezer that is connected to a front opening fridge, the fridge will be controlled by a thermostatically operated spillover fan, the door to the fridge will open out but will have a lip of 150mm to contain the really cold air and not allow it to fall out, it looks pretty cool i think and will cost around 2000$ finished for a 100l freezer and 130l fridge
sean


Hi Sean, I am thinking of building an almost identical size fridge/freezer (90 lt freezer, 140 lt fridge) so it is just a matter of where the internal divider goes overall the same sizes.



I found ozefridge via the multipanel website as I had not decided on the workings yet but am building the cabinet soon and had heard that multipanel had an excellent r rating and was recommended as a good insulator. Ozefridge also endorse it hence their link on the multipanel website.



Do you mind answering a few questions now that you have it all up and running. Would you recommend this to others or do you have any regrets or things you would do differently? I assume you went eutectic, which of their kits did you go for for that cabinet size? I was also considering asking for a 3 meter hose instead of 2 meters and putting the unit in an under seat in the cockpit to move the noise away from the living areas, any thoughts on this? Doe their claims of running for a say 3 hours a day in a single go rather than the usual cycle on cycle off of a evaporator plate hold up for you? Are you finding that you are using the amps each day they say you would? I am told the biggest regret people have is in the thickness of insulation, I have allowed for 150mm walls and 200mm base and 150mm top, is this what you went with?



Any advice in retrospect would be a great help.



Cheers, Paul

puremajek
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refrigeration

Post by puremajek » Tue Apr 13, 2010 2:28 pm

Just completed a two week sail which included the use of a portable 3-way fridge/freezer. Was easily stowed below the forward bunk and definitely kept all the gear frozen for the full period. The 70lt unit did however live up to its 5A specs which did put a strain on the battery bank (especially after we left the generator at home) remembering that we also have a 110Lt fridge.



It was the FridgeMate FM70 which we picked up new for $900 off Ebay (and came with remote temperature gauge) and are yet to find fault. It is made by a EvaKool in Caloundra. Its now back in the shed till our next big trip away.
James
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http://www.diycatamaran.com
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tuskie
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refrigeration

Post by tuskie » Mon Sep 06, 2010 1:21 am

Paul,

Nice to see Mahna Mahna's (or Yikes's) frig and freezer taking shape.



Just a thought about insulation, efficiency, space and all that. I saw a clever idea (yes, it was on a Fusion 40!) where despite about 150 mm of quality insulation under a Ozfrig powered freezer there was still a bit of "cold leakage" down. Instead of trying to stop this by adding thicker insulation the owner simply used the cupboard underneath to store fruit and veges. These did not freeze but were certainly kept nice and cool.



This space is where you are planning an electrics cupboard. On the side of the bridgedeck, forward of steps. Perhaps it is good that some of these components are also kept cool by thermal leakage from above. eg inverters.



Perhaps this, under freezer area would make a great wine cellar for tropical cruisers? Just an idea. Keep up the good work and thanks for sharing it with us.



Mark

mahnamahna
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Location: Gosford NSW

refrigeration

Post by mahnamahna » Tue Sep 07, 2010 10:08 pm

tuskie wrote:Paul,
Nice to see Mahna Mahna's (or Yikes's) frig and freezer taking shape.

Just a thought about insulation, efficiency, space and all that. I saw a clever idea (yes, it was on a Fusion 40!) where despite about 150 mm of quality insulation under a Ozfrig powered freezer there was still a bit of "cold leakage" down. Instead of trying to stop this by adding thicker insulation the owner simply used the cupboard underneath to store fruit and veges. These did not freeze but were certainly kept nice and cool.

This space is where you are planning an electrics cupboard. On the side of the bridgedeck, forward of steps. Perhaps it is good that some of these components are also kept cool by thermal leakage from above. eg inverters.

Perhaps this, under freezer area would make a great wine cellar for tropical cruisers? Just an idea. Keep up the good work and thanks for sharing it with us.

Mark


Hi Mark, I did not realise I had officially told everyone about Yikes. In case I have not told everyone, we wont be launching as mahnamahna, 5 years is a long build time and we have changed our mind about the name. It was a joke name only chosen after we decided to build and despite being known for it via our blog we have no emotional attachment to the name, and Yikes does hold some emotional meaning to us and will be much easier to translate over radio and phonetics so we will launch as Yikes. (Upon launch our mahnamahna website will have a follow our cruising link to the new yikes website when it too launches and mahnamahna will just sit there as a reference for anyone interested in years to come).



I am yet to commit to the fridge innards due to lack of money, but I am sure to go with a eutetic from this or another QLD maker. I will most likely put the heat exchanger in the shower recess behind the shower side wall because it vents out to the cockpit and moves the noise making part away from the bedrooms, just need to contact the eventual supplier about how long the fluid hose can be.



And yes I had not considered that some cool leakage into what will be a "hot" cupboard with an inverter in it might not be such a bad thing so long as the leakage is withing tollerances, otherwise the fridge works too hard. I am likely to have 200mm of insulation at the bottom so I dont lose cold through the bridgedeck and 150mm walls but would love for them to only be 100mm because the cupboard is only 600 deep front to back so using 300mm of it up with insulation and leaving only a 300mm cavity is a bit galling and what I may do is switch from 150mm wall insulation to 100mm wall insulation about half way up so as to make the fridge 400mm front to back for the top half of the fridge (the fridge is 900mm deep top to bottom of which 200 is lost to the insulation at the base and 100mm at the lid and top so that leaves a 600mm deep top to bottom usable area and the final dimension is 1300mm wide of which 300mm is lost in the walls so 1000mm is usable of which about 600mm will be fridge and 400mm will be freezer). Changing the wall insulation thickness half way up will provide a ledge inside for the top tray/basket to sit on, and below that the narrower tray/basket would hold the less fequently used items.



The idea of a fruit and veg drawer is a good one and worth thinking about, but adds complexity into the build. One idea that is simple and that I am going to do is to pass a coiled copper pipe through the bottom of the fridge through which water will pass on its way to a seperate water fountain at the kitchen sink so that cooled water is always on tap. The coil would hold about a liter so as a cooled liter is pushed out at the tap a new liter enters the coil to be cooled by the fridge. It does mean the fridge works a tad harder but not by much and likely to use less energy than the lost spillage from having to open the fridge for a bottle or jug of cooled water on a semi regular basis. Very easy to engineer into the fridge and seal through the insulation.

tuskie
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refrigeration

Post by tuskie » Wed Sep 08, 2010 12:45 am

Paul,

Your insulation tapering or stepping to thinner in the upper sections sounds like a good idea in the balance between space and power efficiency.

The cooling effect on the cupboard space below the freezer was probably accidental and not planned, but was turned to good use.



A cold water tap at the galley sink? Not sure about that one. Are you having a sea water tap as well? If so, that would make four taps: hot, cold (ambient), cold (from frig) and seawater. A bit confusing. Perhaps one of those post mix taps like they have at pubs with four bottons on the hand piece? LOL

More seriously, perhaps a door mounted water dispenser unit from an old frig could be mounted near the frig away from the sink. This would reduce the pipe run length, keep the water temperature cooler and save tap rage at the sink.

IMHO a seawater rinsing tap is great for saving fresh water, so I would keep that option.

Mark

mahnamahna
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refrigeration

Post by mahnamahna » Wed Sep 08, 2010 1:20 am

tuskie wrote:Paul,
Your insulation tapering or stepping to thinner in the upper sections sounds like a good idea in the balance between space and power efficiency.
The cooling effect on the cupboard space below the freezer was probably accidental and not planned, but was turned to good use.

A cold water tap at the galley sink? Not sure about that one. Are you having a sea water tap as well? If so, that would make four taps: hot, cold (ambient), cold (from frig) and seawater. A bit confusing. Perhaps one of those post mix taps like they have at pubs with four bottons on the hand piece? LOL
More seriously, perhaps a door mounted water dispenser unit from an old frig could be mounted near the frig away from the sink. This would reduce the pipe run length, keep the water temperature cooler and save tap rage at the sink.
IMHO a seawater rinsing tap is great for saving fresh water, so I would keep that option.
Mark


The problem with having a tap anywhere but where there is already another tap is that you have to plumb out the waste. It could be argued that with a drinking water dispensing tap only (which is what this will be) that more care is taken, a cup is usually directly in line and no waste is needed and this may be so considering we have a bench top water cooler/purifier in our house and other than occasionally spilling some water on the bench that is easily wiped up it is nowhere near a waste pipe and you just push the lever with the cup so perhaps we could do this without the need for a waste pipe. I will give it more thought. I was considering a hot cold single mixer and had not given a lot of thought to a sea water sink but am considering it.



Regarding the step in the wall thickness takes into account that the higher you go in the fridge the less insulation for a given leakage rate given that cold air falls. A step is convenient in that it allows for a step onto which the baskets sit. I have a bit of a plan for how the fridge will be made and it includes making an mdf mold and making the fridge liner out of chop strand with gel coat on it on the mold so that little to no internal finishing will be needed. It will have very rounded corners so that there are no crevices to trap dirt. Once made, I first put all of the insulation into 3 of the 4 sides already represented by the 3 side walls already in leaving just the front. Once the insulation is in, the pre-made internal fridge liner goes in then the front insulation and then finaly I have to seal that all in with glass to ensure no air can get into or out of the insulation capsule.



Also molded into the liner will be a stepped lid to ensure the lid when closed traps cold in. I have not yet figured out the nitty gritty of plumbing the fridge mechanism through but will do that before making that mold as it may well include some shaping to mount the eutectic plates.



Anyone who has made one of these fridges please pull me up if I am about to make any blatent mistakes or misunderstandings on how this ought to be done.

kjay
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refrigeration

Post by kjay » Wed Sep 08, 2010 1:54 am

Paul,

Many years ago "Fisherman and Boatowner" magazine published an article that ran over a few issues on how to make a Fibreglass Esky. I know they have archived infomation on their web site so you could check it out. The builder goes through the steps of making molds for the bottom and lid. I think he used coated melamine chipboard for the mold. I know if you find it it will be fairly basic info as you would now be considered a fibreglassing guru with what you have achieved with the build, but you may find it interesting, The Gougeon Bros manual also covers how to build one as well.

Good Luck

John "Sarah 16"

mahnamahna
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refrigeration

Post by mahnamahna » Wed Sep 08, 2010 2:06 am

kjay wrote:Paul,
Many years ago "Fisherman and Boatowner" magazine published an article that ran over a few issues on how to make a Fibreglass Esky. I know they have archived infomation on their web site so you could check it out. The builder goes through the steps of making molds for the bottom and lid. I think he used coated melamine chipboard for the mold. I know if you find it it will be fairly basic info as you would now be considered a fibreglassing guru with what you have achieved with the build, but you may find it interesting, The Gougeon Bros manual also covers how to build one as well.
Good Luck
John "Sarah 16"


Hi John, I have a very detailed pdf from a renowned refrigeration expert in the US that I got from one of the US online boating websites, I can dig it out and email it to anyone interested. I have not referred to it as much as I should and will go back and refer to it again.



I have a boat builder that is going to help me with a mold, although it is time consuming he feels that a male mold that you glass over is the best way to get a "factory" finish to the internal chamber of a fridge, that is, very rounded corners, no seams, no fairing or painting as it comes off the mold with paint already on etc. The inside of the fridge is analgous to the outside of a molded boat in that it is the side that needs the shiny smooth finish. The other side can be rough as it is the side that will then be surrounded and sealed by the insulation panels.



The insulation is a seperate process, and needs to be inside a sealed void so that air cannot get in or out of it or more appropriatly moisture cannot form inside it because it is that moisture that severly restricts the effectiveness of the insulation. So my method is that I have built 3 sides of the cabinet, leaving off the front at this stage. From there I build in the 3 sides walls and the base of insulation, into which the finished internal molded box fits then the front insulation can go on and a front facia wall onto the cabinet. That would just leave the top and lid to be made to seal all of the insulation in. So making the box itself is not a big issue, but not sure if the methods described concur with others that have made similar fridges.

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