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S&S Swan General - Refrigeration Insulation
03 February 2014 - 14:20
#1
Join Date: 03 March 2007
Posts: 240

Refrigeration Insulation
Hi All,

I have decided to modernize our fridge.. I am in the process of putting in a new refrigeration unit and am curious about the existing amount of insulation around the box.. Has anybody got an idea. I figure about 1.5 inches on the sides not sure about the bottom of the box which is the the most critical area. I don't think our boxes badly insulated as I was using around 30 amps per day in the Canaries (20oC) and up to about 50 in the Caribe (high 20s low 30s).. that was until the evaporator plate on our 16 year old unit started to leak… Now that there are new more efficient regulators and compressors it is time to make the move..

All comments advise welcome!!!

Mike Storm Svale

11 February 2014 - 21:19
#2
Join Date: 27 January 2011
Posts: 140

Hi Mike,

I also plan to renew our refrigeration unit. I wonder if it is the original one, but then I am not sure if they make it that long. It is currently positioned under the bunk in the aft cabin, next to the hot water tank, and it is so loud when it runs that we need to switch it off during the night. Is there a smarter location for the unit? The modern ones are silent, so it could maybe go to the same place. I will also look at the state of the insulation this year - key is that it is dry. Our fridge has a handmade (or maybe enlarged) hole at the deepest spot, so that humidity can escape. This hole looks a bit oversized.

Christian IF 411/028

12 February 2014 - 08:34
#3
Join Date: 03 March 2007
Posts: 240

Hi Christian,

The new ones are much more efficient so I am hoping to reduce my AMP usage. I have done a fair bit of research on the issue, no expert but some things are pretty clear.
First the compressor should be kept away from areas that are hot as the compressor needs to be cooled so in hot areas the cooling fan to run more. Furthermore, any of the tubes going by the heat source will be heated. Both these issues mean you will need to run the compressor and fan more generating more heat using more AMPS and so on.. This suggests keeping your compressor close to your hot water tank is not optimal for your system. We keep ours under the kitchen counter top close to starboard bulkhead.. fits nicely and we have it well ventilated. Next is the big drain hole at the bottom of your fridge box. Cold air is more dense than hot air and it sinks to the bottom of the box…. and out this hole to the bilge. So in fact you are loosing the cold air… This suggests you should put a removable plug in that hole so the cold air does not escape. We do this, just take out the plug to remove the condensation, well at least some of it. The next big issue is how much insulation is around the box. Again the most impt area as at the bottom. This is what I am trying to find out.

Hope this helps

Mike

12 February 2014 - 11:00
#4
Join Date: 02 January 2008
Posts: 1547

Dear Mike and Chris
Suggest you consider a system with water cooled condenser, this reduces the heat load in the interior. Referring to the box insulation it is important that moisture can not penetrate, as this reduces the insulation properties. Added thickness is advantageous.
Kind regards
Lars

12 February 2014 - 11:47
#5
Join Date: 03 March 2007
Posts: 240

Hi Lars and Christian,

Yes, the water cooled units are more efficient. The pumps do draw power and one has to worry about fouling and corrosion on the fittings but I think in hot climates they are the way to go.. As we will soon be back in the Northern climes I am having an internal debate on this issue..
I am still thinking that increasing the insulation is the best way to improve the system but this may require putting more insulation inside the box which will be a fun exercise.
Another thing to think about is the evaporator plates..freezer boxes etc.. I had a long chat with a refrigeration guy in Martinique on the problems with the aluminum evaporators..Seems like every time one shuts down the fridge or the compressor the coolant expands. When the compressor kicks in again or the fridge is restarted the coolant contracts. This contract expand cycle causes the aluminum evaporators to flex and develop hair line fractures as the aluminum evaporators become more brittle with age… Note this takes years but it does happen. This is what killed ours. The way around it is to go to stainless steel evaporator plates. These do not suffer from this problem. Sea Frost in the US makes a nice little SS freezer box. Not cheap but I am considering one of these. One draw back is that SS is not as good a conducted for cooling so not quite as efficient as the aluminum units.

All the best
Mike

12 February 2014 - 17:54
#6
Join Date: 02 January 2008
Posts: 1547

Mike
Suggest you also check what Iceberg can offer, they have supplied the refrigeration to many Swans.
http://www.iceberg.dk/
Kind regards
Lars

12 February 2014 - 18:55
#7
Join Date: 03 March 2007
Posts: 240

Thanks Lars they are not far away so I will drop by.

All the best

Mike

14 February 2014 - 09:20
#8
Join Date: 01 March 2007
Posts: 147

Hi Mike, I can't add much to this debate, you sound as tho you are on top of the issues, but the following may be useful. On the 47, there is a top load fridge in the galley, with an original. Small drainage hole. You need telescopic arms to reach and clean this area. A previous owner enlarged the drain hole, fitted a hose to a thru hull bring salt water to the sink via foot pump. With the right sequence of taps and shut offs, I wash the inside of the fridge with hot soapy water and pump out thru the hull using the footpump . ( when at sea of course) it is a practical and easy way of keeping the fridge smelling sweet. If I forget to but the bung back ( long way to reach etc) at least the drainpipe reduces loss of cold.
Heres to good working fridges!

Rob. Sarabande. 47/029

20 February 2014 - 07:57
#9
Join Date: 03 March 2007
Posts: 240

Many different ways to skin a cat!! Given my short arms I think that is a great idea. I will do the same.

Thanks

Mike

24 February 2016 - 19:26
#10
Join Date: 19 January 2016
Posts: 3

Dear fellow members,

Has anyone had experience in re-insulating their frig and freezer cabinets, especially in the earlier Swan 47 model? This experience might include actual removal, rebuilding or replacement of the existing boxes or at least removing the tops of the boxes. Or has anyone successfully added insulation to the insides of the existing boxes? And if so, what material did you use? Finally, has anyone used the relatively new-to-the-public insulation called 'aerogel?'

When I last posted we were still running the original Grunert system with holding plates and using R-12. We are now running two Danfoss keel-cooled units, very efficient, but barely able to maintain proper temps in the high heat of Med summers.

Thanks for help.

Robert Way
s/v Quest, nee Toscana, S&S Swan 47, #12

08 March 2016 - 08:14
#11
Join Date: 03 March 2007
Posts: 240

Hi Robert,

 

Due to time constraints I ended up not doing the major rebuild of the fridge. I ended up drilling holes in a grid pattern thoughout the ice box and then putting insulation behind the walls using the spray cans of insulation. I then repaired the holes and painted.   I was absolutely amazed at how much I needed to fill behind the box.  Yes it is a huge space but it was obvious that the old insulation had either separated from the box or broken down over time.  I then installed a new Seafrost Unit (Danfrost 50 compressor ) with a stainless steel freezer box. The compressor resides under the counter top in the closet between the stove  and the bulkhead up to the quarter berth.  It is well ventilated and as the compressor is very quiet and runs very little and thus is not obtrusive. To try the unit out... I put a 1.5 liter bottle of water in the freezer box ( the rest of the freezer box and cool box was empty).  Two hours later the bottle was frozen solid.

Subsequently I have sailed Storm Svale back over the Atlantic and home to Denmark.  Our power consumption has dropped incredibly!!! Probably a 50 % reduction. As in our east to west crossing on the west to east crossing we used solar the whole way and did not have to use the engine to charge the batteries.  The biggest problem is defrosting the freezer box as within a week or so starts to ice up.  We froze 6 meals before leaving port on each leg making food preparation at sea very easy... The cooler box side works perfectly as well.  WHat I did was put a shelf at about 1/2 way up the box... on the 40s there is an edge on the fore and aft sides of the cooler box to put the shelf on.  Below this shelf I put 3 x 1 gallon jugs of water which I froze at a friends house.  I put meat that I wanted to keep really cold but not freeze on these.  This ended up being semi frozen.  Cold air sinks making this a cold sink.  Interestingly 6 weeks into the trip these jugs of water were still ice. The area above the tray was perfect for veggies milk etc..

The Seafrost units are probably double the price but to be honest well worth it based on performance and power draw.  I do not know about accessability to these units in Europe.   I did a lot of research before choosing and this has definitely paid off.  Ice for sundowners at anchor is now no longer an issue... but we still prefer what we call boat drinks.. as the ice dilutes the good stuff. (;-)

 

For those of you who followed the Colibri story and the loss of the cat off the AZORES. I think we saw Colibri mid Atlantic.. We did see the bows of the Cat  about 300nm out from the AZORES.  It was a rather unnerving sight knowing the story and of the loss of life.  We were very subdued until Flores came into sight. 

All the best 

Mike from StormSvale

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