Buying vs building a fridge ?

[Boo2]

Hi,

I'm quite taken with the Waeco (Dometic) CB 36 and CB 40 fridges on page 18 of their online catalogue. The only thing that gives me pause is the fact that they only have 40mm of insulation and I wondered if there is any advantage to building your own rather than installing a ready made one like the two mentioned ? Is it possible to get a good expanding foam insulation material you could just pump into the space or does it need to be polystyrene blocks cut to fit ?

Any general fridge experiences would be of interest.

Thanks,

Boo2

 

[prv]

I think expanding foam is best used to fill the remaining odd-shaped voids after adding the main insulation in sheet form. I would use Kingspan or similar rather than basic polystyrene though - better insulation for a given thickness and you won't be using much of it (compared to its usual home in roofs and floors) so the higher price won't matter (I assume; I've never actually priced the stuff).

Don't forget you need a cool, well-ventilated place for the compressor, as well as the actual box itself.

Pete

 

[Quandary]

The box for our frig. is stainless sheet rather than the more usual grp, it is mirror finished so you always think there is at least twice as much beer in there, so avoid that. I would go for the build option, on a boat you are able then to optimize the capacity against the space used. As perv says you should use closed cell foam like polyurethane, much more effective for a given thickness than EPS. The only thing you will have in there is the cooling plate but it is useful if you customize the box it to take Ikea type trays or baskets to reduce the time it is open while you dive for stuff which is always at the bottom. Close fitting airtight lid or door. The nearer the compressor is the better, ours is under the seat just in front with generous vents to let the air circulate, you get a wee bit of extra heat in the cabin. A handily located and visible on off switch means that you can check that it is switched off when you are sailing as they are very power hungry.

 

[pvb]

If you build your own, consider including one or more interior lights. I've put red LED lights inside mine, much easier to find stuff during night trips without putting main cabin lights on.

 

[Chris_Robb]

Hi,

I'm quite taken with the Waeco (Dometic) CB 36 and CB 40 fridges on page 18 of their online catalogue. The only thing that gives me pause is the fact that they only have 40mm of insulation and I wondered if there is any advantage to building your own rather than installing a ready made one like the two mentioned ? Is it possible to get a good expanding foam insulation material you could just pump into the space or does it need to be polystyrene blocks cut to fit ?

Any general fridge experiences would be of interest.

Thanks,

Boo2

There are a couple of questions to determine your proposed use of the fridge.

1. Are you going somewhere hot?
2. Will you be close to shore power for replenishing batteries?

If the answer to 1 and 2 is NO, then you must have something with more insulation. The minimum is 3 inches (even for England perhaps) and ideal is 4 inches.

You will also be lucky if a standard fridge will fit where you want it on a boat - Powerboats are generally easier.

I started from scratch, ripped the whole thing out, worked out the volume I would have for a top loader after 4 inches of kingspan all round. I then had a liner made up by Tek Tanks including the lids. The compressor I bought from Penguin with a keel cooler.

It is made in 2 sections so 1 part can be a deep freeze, and the other a fridge. We mostly use it as a fridge. Power consumption once down to temp is very small, and I don't have to charge twice daily (or at all) to keep the batteries up. You see many boats in Greece charging, charging, charging, as their fridges cannot cope with the temperature. This does not have to be the case.

 

[pappaecho]

On my last boat I built a Waeco compressor system into an older fridge carcase, which fitted the space.
In the new ( old) boat there was an Electrolux mains, propane gas/12 volt fridge which sucked power out of the house batteries. It got thrown away.
I bought a modern "table top fridge" for £80 new with an A+ rating, which draws 67 watts.
I bought a 300 watt inverter from Maplin and wired it so it can be run either on mains or the inverter.
We run it the whole time the engine is on, and it gets down to 4 degrees quite quickly and we run it on the house batteries during the day. If we switch it off at 8 pm it gains about 4 degrees over night, and then on again at 8 am it gets quickly down to 4 degrees again, largely supported by an 80 watt solar panel. Assuming there is some sun the fridge runs for days without dropping the house batteries below 12.3 volts.
I dont think you will get such dedicated 12 volt "marine" fridges for about £110, and certainly the Waeco units are considerably more.
I think the key to this is the A+ rating which means high performance insulation and hence less overall losses

 

[prv]

In the new ( old) boat there was an Electrolux mains, propane gas/12 volt fridge which sucked power out of the house batteries.

Yeah - these 3-way fridges will eat power when run on 12v. The reason is that they run on the absorption cycle rather than the normal compression / evaporation system. The benefit of the absorption system is that it's powered by heat, so you can run it by burning gas or paraffin. The problem is that to provide that heat by electricity needs a lot more power than to provide the same cooling effect by turning a compressor.

Because part of the cycle involves liquids descending through gravity, absorption fridges typically also have more restrictions on how far they be tilted over and still work. Maybe special boat ones are more tolerant, but domestic and caravan ones have to be level within a few degrees.

Pete

 

[rascacio]

Hi,

I'm quite taken with the Waeco (Dometic) CB 36 and CB 40 fridges on page 18 of their online catalogue. The only thing that gives me pause is the fact that they only have 40mm of insulation and I wondered if there is any advantage to building your own rather than installing a ready made one like the two mentioned ? Is it possible to get a good expanding foam insulation material you could just pump into the space or does it need to be polystyrene blocks cut to fit ?

Any general fridge experiences would be of interest.

Thanks,

Boo2

If you're building your own then check out 'Aerogel' bit pricey but it is excellent and now available in small quantities.
Google's yer man.