Building a fridge from scratch

[bedouin]

As with many boats of the same age, my boat as a built in "cold box" but it is not actively chilled. Now I am getting tired of warm beer and so want to fit a compressor and convert it into a fridge.

Initial investigations suggest that there is not sufficient space around the box to fit an adequate amount of insulation even if I could get to it so I am forced to consider ripping the existing box out and building one from scratch that is a little smaller but much better insulated.

Has anyone taken this approach - and if so what materials did you use - I have been looking at some form of plastic-faced board for the inside but I don't seem to be able to find a suitable board at a reasonable price. I was hoping to be able to find plastic-faced PU insulation board, but so far google has not been able to find any. Those boards I have been able to find are either chipboard (not on a boat thank you) or expensive "shower panel" types

 

[pappaecho]

I had a strange size of space to fill and could not find a current commercially available complete fridge (12v). However, I was in a Caravan reclamation yard, and spotted a fridge which fitted the space almost exactly, and the inside was quite Ok even though the ammonia based system had had it. I paid a massive £5 for the remains, cut out the ammonia system and cooler plate and replaced it with a Waeco unit, which was mounted above the fridge itself. Job done!

 

[sarabande]

I'd certainly go for the Waeco 'engine', and I've heard good reports of Celotex as insulation boards from another non-boating world. They even do a board which is non-flammable - just in case !

http://www.celotex.co.uk/

Their service department advises on joint tape and all the other details.

 

[MarkJohnson12345]

I have converted my cool box into a fridge.

The Waeco compressor lives under the sink, and the plate makes ice in the cool box.

Luckily, the Sadler coolbox has nearly 2" of insulation, so I have not added any more.

My chums in a Westerly have done the same, but added insulation on the inside in the form of polystyrene sheets, about 20mm thick. And they sail in the Med so that works for them.

 

[bedouin]

I'd certainly go for the Waeco 'engine', and I've heard good reports of Celotex as insulation boards from another non-boating world. They even do a board which is non-flammable - just in case !

http://www.celotex.co.uk/

Their service department advises on joint tape and all the other details.

I am certainly intending to use celotex for the insulation - my local Wickes sells both the 25mm and 50mm sheets at a very reasonable price. They are fairly rigid but I will clearly need an inner liner and that is what I am wondering about. The only suitable materials I have found at the moment are £80 plus for a sheet.

For the compressor I am certainly intending to use the Waeco unit - probably with the accumulator evaporator to minimise battery drain.

 

[bedouin]

My chums in a Westerly have done the same, but added insulation on the inside in the form of polystyrene sheets, about 20mm thick. And they sail in the Med so that works for them.

That is certainly an approach I might adopt - but if I do add additional insulation inside the cool box then I will need to line that with something - I wouldn't want to have the food directly on the polystyrene / PU sheets

 

[sarabande]

these people, who have what must be the longest website name in the world

http://www.refrigeratedvansforsaleuk.com/refrigerated-boxes.html

seem to have lots of answers. May be worth getting their free advice on the liner they recommend ?

The alternative is thin skins of aluminium bonded to the insulating sheets, and then sealed with Screwfix's frame sealant.

 

[Salty John]

When I made mine I had the box made up by a small local company that made advertising displays. It was fibreglass with a gloss interior surface and a lip around the top so it could be attached to the underside of the counter top. There was a drain hole in one corner. I think it cost around £50.

 

[Rafiki]

Building fridge

I'm surprised that you can't get to the outside of the coolbox to add insulation. In my Westerly I could get to some sides and simply stuck cellotex type material to it (there are many similiar alternatives - I got mine from a skip at a bilding site, but not many of those around these days). The sidews I couldn't access I carefully used expanding foam through holes I drilled through bilkheads to get to the outside of the coolbox.

We also made a new lid for teh coolbox out of an offcut of a beech worktop and filled the drain hole of the existing cool box with expannding foam and then polyester car body filler; no point in letting teh cool air drain into the bilges

The whole conversion was probably the best single piece of work we did to the boat! with the addition of a second battery and a decent battery charger we rarely turn the fridge off ( assuming we are either on shore power at night or 2 hours of matoring a day)

Regards

 

[Chris_Robb]

As with many boats of the same age, my boat as a built in "cold box" but it is not actively chilled. Now I am getting tired of warm beer and so want to fit a compressor and convert it into a fridge.

Initial investigations suggest that there is not sufficient space around the box to fit an adequate amount of insulation even if I could get to it so I am forced to consider ripping the existing box out and building one from scratch that is a little smaller but much better insulated.

Has anyone taken this approach - and if so what materials did you use - I have been looking at some form of plastic-faced board for the inside but I don't seem to be able to find a suitable board at a reasonable price. I was hoping to be able to find plastic-faced PU insulation board, but so far google has not been able to find any. Those boards I have been able to find are either chipboard (not on a boat thank you) or expensive "shower panel" types

Hi - I ripped out my fridge last winter and started from scratch. I worked on the basis of 4 inches insulation underneath, 3 inches on the sides and 2 on the top. The insulation was layers of 25mm silver faced insulating board from the builders merchant. The liner was made to measure by Tek tanks, and the refridgeration by Penguin with a keel cooler. The whole thing was not cheap, but is designed as a freezer/fridge. Uses b-all juice as it is so well insulated, and runs happily at -15C in the freezer side and 4C in the fridge.

Space for the insulation is the main problem, but certainly worth adding as much as you can. 2 inches allround is OK for uk, but more would be ideal. It pretty well directly relates to the amps used.

 

[Clyde_Wanderer]

That is certainly an approach I might adopt - but if I do add additional insulation inside the cool box then I will need to line that with something - I wouldn't want to have the food directly on the polystyrene / PU sheets

Why dont you laminate the inner cooler box from polyester resin and csm (a couple of layers would be sufficient) then bond insulation to the outside of it.
C_W

 

[bedouin]

It is not so much that I can't get to the outside of the box, as that there is not enough space to add sufficient insulation. I am aiming for a minimum of 50mm all round and with the current size box i would struggle to get 25mm in certain places. Given the other difficulties with access (e.g. the side between the box and the hull) it seems easier to start from scratch than to try to bodge a solution round the existing box. Clearly the expanding foam route would be the simple but the result would not be as good as one with more insulation.

 

[LadyInBed]

I made mine from a storage box:

Removed the old front opening one and cut a access hole at the top

Used another small storage box as the access point

Put a frame round the storage box

Then slid it in from the front with high density insulation sheets around it

The compressor is mounted in another area

 

[William_H]

Refrigerator

The fridge needs to be top loading so that when it is open cold air can not flow out.
You need a frozen section with a section also for just cold not frozen. This could be achieved by having a drop in box from the top that is insulated from the frozen section.
The idea of using a plastic storage container as the liner has much merit. It is smooth easy to clean and could be replaced if damaged.
The alternative would be to glue more insulation to the inside of the existing box then try to lay fibreglass over the insulation to make a smooth liner. This means you can cope with any shape but will be difficult/tedious to get a smooth surface. But doable.
If the insulation is polystyrene then you must use epoxy or possibly vinylester resin. To use polyester resin you will have to have polyurethane foam. olewill

 

[bedouin]

The top loading is a given - that is the only access there is to the hole where the current coolbox is (which is bounded on four sides by the engine, the cooker, the hull and a bulkhead to the cockpit locker which is why access is tricky).

I was wondering about whether it is feasible to have both a freezer and a fridge section in the same box, cooled by the same evaporator plate but I am not sure if that can be achieved, particularly in a set up where I hope that the compressor will not be running very often (e.g. using an accumulator).

I do like the ideas of either a storage box, or a tek-tanks type bespoke fabrication. Both sound more satisfactory solutions than building it out of flat panels as I had been envisaging

 

[Chris_Robb]

I was wondering about whether it is feasible to have both a freezer and a fridge section in the same box, cooled by the same evaporator plate but I am not sure if that can be achieved, particularly in a set up where I hope that the compressor will not be running very often (e.g. using an accumulator).

Tek tanks built an oblong box divided in the middle with half inch of insulation between fridge and freezer. There are 2 holes of 2 inches diam in the top of this divider, into one of those holes it fitted a thermostatically controlled fan to suck freezing air as required from the freezer side to the fridge. You can therefore choose to run the Freezer as a fridge as well by just not setting the temp so low. The biggest problem was to work out how to get the maximum space in the fridge possible without compromising the amount of insulation you have. Penguin have a calculator for volume on their website which you may find useful.

Have you thought what min-max volume you need. The original oceanlord box was 170 ltrs - with contents stored on the heap system, which meant it was impossible to find anything. We now have storage of around 110ltr and have 2 wire baskets in each section (made by hamster) which now means we can use every available space and still find stuff. Its important when designing the height of these boxes to make sure it will store a standard wine bottle. Champers and Muscadet require a taller box!

 

[fisherman]

Haven't read the whole thread so apologies if this is already suggested. You could line the celotex box with food quality white plastic sheet as used to line kitchens, where it is stuck to plasterboard, angle corner and other components available also. Google has plenty.

 

[Billjratt]

You're lucky having an existing coolbox to start with. (I had to use a basin and a waste bin to make the wipe-clean containers.
A slab of loft insulation cut up and the gaps filled with expanding foam have provided adequate insulation, but something to be aware of is condensation between the insulation and the container. We used a waeco.

 

[bedouin]

I have been thinking of trying to bond a plastic sheet directly to the celotex but I am not sure how well that would work. I don't know if say 2-3mm PVC bonded to 25 or 50 mm celotex would be sufficiently rigid or whether it would be necessary to add a further layer of plywood. I would like to hear from anyone who has done that successfully.

As far as the size is concerned - the existing box is probably about 150l, but is a strange shape as it fits to the side of the curved hull so has only a very little flat bottom. That makes storage in there rather difficult. The size of the replacement will depend a bit on what shape fits reasonably in the hole. By the time I have added the additional insulation and taken out some of the corners I imagine that it will be somewhat less than 100l, which should be fine. In practice 50l would probably be adequate for my usage.

The use of the space inside is also a bit of a challenge, the irregular shape does not really lend itself to the use of baskets, and the access at the top will have to be comparatively small compared to the volume of the box itself which will also make using the space difficult.

 

[capsco]

Previous poster mentioned using caravan/domestic fridge and waeco engine, could aditional insulation simply be added to exterior of this type of setup and be efficient?