DIY Fridge

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david100952

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I have a Superseal 26 and after a 2 week cruise this summer when we sometimes found it difficult to find ice for our portable cool-box, I have decided to go ahead with a project I have had in mind for a couple of years and convert a storage area to a fridge. I have looked at conventional compressor/evaporator fridge kits but also have considered converting a 12v portable unit which uses the Peltier/Thermoelectric units but have been told at various times that they are inefficient. I then found out quite by chance that the Parker 27 (later version of my boat) had a "Supercool" fridge fitted and investigation revealed it is actually a Thermoelectric unit which the uk dealer claims IS very efficient.

The question is: Does anyone have any experience with doing such a project or indeed the Thermoelectric cooling which I believe also powers 3 way caravan type fridges. I only sail for weekends and the once a year cruise so not looking for much more than keeping bacon and butter fresh for a few days, as such I am tempted to convert a 12v £60 picnicc fridge with the gubbins in the lid to a built in with high spec insulation. To keep SHMBO happy it must be a fitted and well finished part of the galley rather than a Heath Robinson add on that reminds her of the horrors of camping holidays but I don't want to spend money on a compressor system if I don't need to as most will cool a space many times greater than the 30 litres we have and need.

All suggestions gratefully considered.....
 
Caravan fridges are absorption types, extremely inefficient on 12 volts as the power is used to provide heat. Expect them to consume anything up to 10 amps.

I have a Halfords Peltier cool box, the biggest one they do. It would drain my two 110 Ah batteries overnight if left to do so. Very inefficient, for one reason it has no thermostat but runs constantly, drawing something like 6 amps.
 
They are very inefficient. If you are going to do all that work use a compressor fridge.
 
The only type of fridge which suits my style of cruising is an absorption one running on gas. I tend to anchor for a week or so in one place in UK waters and there is no way that even my 80w of PV could cope with a compressor fridge.(along with the computer/radio/heater!!)

I use a 3-way top-loading unit. It uses around 2Kg butane/week. They do need to be fairly level, so usually don't work when sailing. When motoring I run mine on 230v via an inverter .... far better than using 12v directly. It's essential that you install an external flue - and provide adequate combustion air. (and a CO monitor).

(Time to reach into it for an ice-cold beer ;) )
 
we have a Supercool unit installed in what must have been the old ice box. it probably is inefficient compared to a 'proper' fridge but we find it works perfectly, keeps things cold not just cool and doesn't seem to drain the domestic battery although when we are crusing we always use mains power in marinas and do a bit of motoring every day. it has a built in thermostat so it doesn't remain constantly on. i also have a voltmeter and even rswitched on 24 hours a day with no shore power and very little motoring the meter has never gone out of the green on the domestic battery. maybe if we were starting from scratch i'd look at a 'proper' unit, but whoever converted our ice box used a Supercool and its ideal for us. for what you describe i think it would be ideal for you too.
 
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I use a Waeco CF18 compressor coolbox. In UK summer conditions it uses 500mA at 12V averaged over time. You can't get cooling more miserly than that. I wonder if you could buy some of the internals as spare parts for your installation. Anyone who says that any thermoelectric cooling is efficient is just spouting marketing bolleaux.
 
Don't waste money on a highly inefficient unit.

Instead buy either an ASU-Isotherm or Waeco unit with a holding plate and a Danfoss compressor unit.

I converted the ice-box on my Parker 31, 20 years ago and have never regretted the the action. You'll need to improve the insulation on Bill's icebox - in impossible-to-access paces I used urethane building foam or a sandwich of aluminium polystyrene, sold under the Thinsulate brand name, allegedly as good as 150mm of glass-fibre for a 15mm thickness.
It's worked perfectly in the Med for the last 10 years in ambient temperatures as high as 38C.
People will try and persuade you that you have to have a water-cooled heat-exchanger - providing you adequately duct the air I've found normal air-cooling totally adequate.

http://www.isotherm-parts.com/index.php?main_page=index&cPath=4_10_61
 
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Many thanks for the advise.....looks like a compressor fridge is the way to go and I will be furthering my research at the Boat show next weekend.
 
Penguin marine have a good range of fridges and parts to build your own, as do Waeco, I will also be talking to them at the SIBS, I am interested in what material to insulate the box. Charles above mentions Thinsulate, but I can only find reference to clothing products, Celotex is mentioned in a recent PBO article, but Spacetherm aerogel seems to be one of the best insulation materials altho' expensive. Does anyone have any other suggestions.
 
I did a lot of work in Berthons in Lymington a few years ago and they used to make us some standard HD foam and they stuck melamine liner to it then cut to shape and seal with sikaflex. It was a fantastic job and looked like a built in the factory unit. done on both sides it would make an excellent portable fridge and would be very light. for info Ideally a fridge should have 220mm of insulation and will be extremely economical on power if that is done. I had one on my boat in Mallorca and it was amazing it had a waceo unit with a holding plate and about an hour running with would freeze the plate and it would hold all day with no power usage at all. obviously it was better if I let it cycle on the thermostat but was great for day sailing and would last for days with a small solar panel topping up the battery.

Leighb said:
Penguin marine have a good range of fridges and parts to build your own, as do Waeco, I will also be talking to them at the SIBS, I am interested in what material to insulate the box. Charles above mentions Thinsulate, but I can only find reference to clothing products, Celotex is mentioned in a recent PBO article, but Spacetherm aerogel seems to be one of the best insulation materials altho' expensive. Does anyone have any other suggestions.
Click to expand...
 
Hello again
Thank you for the helpful advice from all when I was planning this project (see previous post 6-9-13). I am in the final stages of acquiring the materials having purchased a Waeco compressor and plate, Reticel 50mm insulation and construction materials. What still troubles me is the design of the lid and seal for the top loading storage cavity which I am converting. It is currently a large cavity housed within the internal BRP moulding and is accessed from the top by a simple small opening without a lid. I had complicated design worked out involving a SS liner with an in-channel fridge seal fitted around the lip but I note from looking at various boats at Excel that new manufacturers use little more than the weight of the lid and a "rubber band" seal. A worldly associate suggests that cold air is heavier than warm/ambient air and therefor a seal may not be needed at all!! The only reference I can find in other threads that specifically mentions lid design opted for a bevel edge but I am sceptical about getting it to fit flush to the existing worktop level and it being easily dislodged in heavy weather. I have no doubt I could eventually find a solution through trial and error but for the risk of cannibalizing the GRP mouldings that form the roof of the soon to be fridge and my wish to spend some of my advancing years sailing rather than correcting mistakes. It seems that I am a perfectionist so I do that too much already!
 
ianabc said:
One piece,

perhaps use 12 volt computer fan to duct warm exhaust air to bilge

available world wide

uses standard Danfoss BD 35 compresor

in future if repair needed

then remove unit and take in back pack to repair shop


http://www.defender.com/product.jsp?path=-1|2276204|2276226|2276231&id=323775
Click to expand...

Looks like a neat bit of kit and the unit is quite small at 6x14" so would normally fit between the curve of the hull and the fridge box. As stated some kind of fan to expel the hot air would be needed. is it available in UK?
 
I used two stackable lunch boxes, top half of one to line the hole, bottom half of the other to make the lid (filled with insulation) then topped off with hardwood.

PICT0434.jpg


PICT0432.jpg


PICT0464.jpg
 
I have finished mine also. It has a full sized lid, which is the seat base of the original locker, with added insulation. It sits on a D section rubber seal a few mills thicker than the "dry" space which I am pretty sure will provide a more than adequate seal. As you say cold air sinks, so it is just important to stop any leakage at the top which will allow mixing of warmer air from the cabin.
 
charles_reed said:
Don't waste money on a highly inefficient unit.

Instead buy either an ASU-Isotherm or Waeco unit with a holding plate and a Danfoss compressor unit.

I converted the ice-box on my Parker 31, 20 years ago and have never regretted the the action. You'll need to improve the insulation on Bill's icebox - in impossible-to-access paces I used urethane building foam or a sandwich of aluminium polystyrene, sold under the Thinsulate brand name, allegedly as good as 150mm of glass-fibre for a 15mm thickness.
It's worked perfectly in the Med for the last 10 years in ambient temperatures as high as 38C.
People will try and persuade you that you have to have a water-cooled heat-exchanger - providing you adequately duct the air I've found normal air-cooling totally adequate.

http://www.isotherm-parts.com/index.php?main_page=index&cPath=4_10_61
Click to expand...

Air cooled condensers can be adequate but at high external temperatures they are not as energy efficient as water cooled. On a hot Med day where the air temperature could be 35 degC and the sea temperature say 25degC you would have a 10degc advantage by using sea water to cool the refrigerant. This lower condensing temperature translate to less power used for the same amount of cooling. I am not suggesting you need to go water cooled for this project. I would use a small waeco air cooled unit. This will be ample for this application and not too pricey.
 
I was a bit sceptical when my browser opened revealing only the first two photos but then the third image of the finished project came into view and I am impressed - nicely done! Is there a rubber seal around the lid or is it a snug fit that does not require additional sealing? The size of the opening is about the same proportion of the food locker I am converting but is off to the side of the cavernous interior so I have a challenge in fitting the insulation and the liner but your project has given me a different perspective which has got the grey cells moving in new directions, Many thanks
 
David seems to have bought a fridge kit. That is fine however I would have suggested for him and for others that a good large well insulated box is the first step.
The next step after fitting this is to try ice in large containers (2l milk bottles or even larger if you have a large freezer at home) You may find depending on ambient temp and your holiday requirements this may suit very well. One trick if you have a big box is to put the ice in an insulated bag to stretch its life., from there you fit a fridge unit into the box if you reckon you can power it.
I have a WAECO CF25 portable fridge. It does have lots of freezing power but does use more current than it should due to inadequate insulation. Good in the car though.
good luck olewill
 
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