Improving fridge efficiency

[Keiron]

Any one any ideas on simple ways in which to improve the insulation of the fridge/cooler so that it will hold the cold for longer, particularly when on anchor, so it doesn't suck all the amps out of the battery?

I am thinking more about insulation than things like filling it and using cool blocks (already have 3 of them!) and am toying with using an old camping mat to line the inside of the fridge to help stop the cold dropping out the base.  Would this work or would it be better to try to insulate outside the fridge to do this and also prevent heat entering from exterior.  However getting access to the exterior is a contortionists nightmare or involves practically tearing the galley apart, hence the interior insulation idea.

Any ideas on what exterior insulation to use, I guess fire retardant would be essential. 

Keiron

[Odysseus]

If you put "fridge" into the search box in Bavaria help file you will see the improvement I have made on Odysseus and I am in France now and the temp is 29c the fridge runs for 12 Min's every hour.
I can send you more photos if you want but you may have to wait as I do not always have wifi.

Odysseus

[TonyS]

Bav 36, 2003
We have 2 mods.
Firstly we use a car interior/ exterior thermometer (sits on top behind the lid) with the sender in the bottom of the fridge. We then set the control to average 5C (recommended fridge temp). It cycles between 3C and 7C
Secondly we have a 1" slab of polystyrene cut to just fit in the opening and stuck with PVA to the lid.
Like Odysseus we use 12mins every hour which a 40watt solar panel will supply.
We have 3 sponges on the floor under the condenser. These fill with water and if taken out and squeezed every week then defrosting is not required.
Tony

[Stuart]

Hi Keiron

On our Bavaria 42 (2005) The fridge died so I replaced it with a Frigoboat system.
I also cut the plywood out underneath the box which gave me access to all the sides and bottom of the fridge to install rigid foam. Increased anywhere  from 1 1/2" to 2 1/2" more insulation, filled the lid with spray foam also added about 2 inches of foam. Installed "starboard" lip inside  with gasket seal and slide bolts to keep the lid secure.
Easy afternoon project
I figure in a 24 hour period at anchor it uses about 16 to 20 amps in 78 to 80 degF water.

[Keiron]

Wow! where did the last 2 months go?  Oh yeah work and sailing!!

One thing I tried while on the boat this summer was newspaper and cut open 6l water bottles.  You take a few pages of the local rag and scrunch them up in the bottom then cover these with a second layer of folded paper.  Then take 4 or 5 pages and fold in half lengthways and fit inside the bottle to form a wall.  Cheap but relatively effective.  We put 4 bottles of bitter lemon in to chill while on the mains and a spare thermometer to see the results and after a day sailing the top of fridge was at 20C, the base around 15 but the bottles were still reading around 10C.  Kept the mixers cold anyway :-)

Tony, like the idea of using the car interior/exterior thermometer to track the temp.  We have a "hang off the rails" thermometer which is great but you need to open the top to see how cold it is which is self defeating.

Stuart,  I presume you mean filled the inside of the top with spray foam by making a small hole in it and squirting away?  Did you use normal white polystyrene rigid foam around the fridge box or was it something more specialised.

Odysseus, drop me a message with your email and I'll return the mail so you can send some photos, no hurry as I'm currently sat on an oil rig in Singapore going nowhere until October.  I know what you mean about Wifi, it's painfully slow here.

Once I get round to this project I will try to take photos and post a new topic to share the findings

[Keiron]

Well were did the last year go?

A post season update on our fridge is due.  Having lined the entire inside of the fridge with 5mm camping mat foam (some of which is foil backed) and using a small In/Out thermometer from Maplins we have been able to determine that our fridge will happily keep between 2 and 10ºC using 15mins/hour at 6amps.

This is a dramatic improvement on the basic unlined fridge and lining the interior was a whole lot easier than pulling to galley apart to line the outside.  My thinking is a doubled up lining will further improvement in efficiency without losing any interior space and I plan on building a triangular block for the rear sloping wall to fill the dead space and give an additional shelf.  I also think I will try to line the underside of the fridge to reduce the heat rising up from the compressor unit and add a PC fan (or 2) to help dissipate the heat further.

Keiron

[robgs]

I installed a 4 in computer fan (very low amps) to remove heat from the compressor compartment. Can be linked to run when compressor runs.

[nornie lees]

Ok Chaps this is what i did to my Bav 37 fridge.

1. 50MM celotex bonded to top of compressor ceiling, i used no nails BQ. (THIS STOPS ANY HEAT RISING THROUGH FRIDGE FLOOR.).
2. Removed fridge lid bottom and installed BQ foil bubble roll, designed for loft insulation.
3. 50mm celotex to fridge floor, with foil bubble insulation over.
4. All the above had their edges sealed with a foil air ducting tape, bought from Jewsons builders merchants.

now only need half the fridge setting to achieve cool fridge. 3----5c.

rgds Ray

[jezzb]

Hi All,

Excellent tips which I will definitely apply on my boat.

Will a digital thermometer further improve performance ? I was just wondering as a digital thermometer should be more accurate that the factory installed mechanical thermostat found inside the fridge.

BR
Jezz