Any experience of keel coolers for fridges?

Keith-i

Keith-i

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I'm just planning an upgrade of our rather small and basic fridge and have been looking at the Penguin Frigo range. Whilst I'm sure the standard compressor/condensor version is far more efficient than our existing unit, I was rather taken by the keel cooler for the condensor side. It makes a lot of sense and will also keep the noise down by eliminating the need for a fan. Before I get the sales patter from the Company themselves, I just wondered if there was any first hand experience out there. My biggest question is what you do about antifoul as I assume the thing can't be painted otherwise its permeable sintered nature would get blocked.
 
I've been looking at their stuff recently too. The first drawback is the fact that our boats are high & dry on our moorings for 6-7 hours per tide. I would've liked to be able to run the fridge for a few days between trips away rather than emptying out the fridge every trip.
I am looking at fitting a freezer and keel cooling seems to be so effective I was wondering if I could also run my existing fridge off the same cooling unit if it was specced high enough. Not quite worked that one out yet.
 
I have a Frigaboat unit with keel cooler and I think it is brilliant. It uses hardly any power, but I have to say that the fridge gets much colder when the boat is on the move. that is not to say it does not get cold enough in a marina, it does. It is just that when you are moving it can easily get cold enough to freeze and split any tins in direct contact.
 
I have an isotherm unit in each of my two boats. One has the exchanger fitted in the galley drain (and this incidentally works fine even when boat is ashore in the tropics) and the other boat has the same unit but is fan cooled. The latter is quiet and just as efficient - and cheaper. Both have the smart control system which allows system to run faster and cool holding plate when more power is available such as when running engine.
The most important thing is to have the best possible insulation on the fridge itself. Achieving that pays huge dividends.
 
I have a Frigoboat with a keel cooler and I am quite happy with it. There are a couple of things to care of: 1) changing the zincs every two years and 2) cleaning the cooler surface once a year when renewing the antifouling. I do not use antifouling on the cooler but... I do not really know if this is the right thing to do.

Daniel
 
Keith-i said:
I'm just planning an upgrade of our rather small and basic fridge and have been looking at the Penguin Frigo range. Whilst I'm sure the standard compressor/condensor version is far more efficient than our existing unit, I was rather taken by the keel cooler for the condensor side. It makes a lot of sense and will also keep the noise down by eliminating the need for a fan. Before I get the sales patter from the Company themselves, I just wondered if there was any first hand experience out there. My biggest question is what you do about antifoul as I assume the thing can't be painted otherwise its permeable sintered nature would get blocked.
Click to expand...

I am wondering what "permeable sintered nature " means. I sort of assumed that the keel cooler would be a simple copper pipe running parallel to the keel and protruding from the hull fore and aft with the hot gas in it. The copper by its nature should not attract fouling although I imagine the hull under the pipe might get fouled and so reduce heat transfer area. I could not get much info from Penguin web site. can anyone explain for my curiosity. olewill
 
We have the Frigo version with the 'sintered' keel cooler. (To olewil: I think sintered in this context just means lots of surface area for not a lot of volume sticking out of the bottom of the boat.)

Comments ref insulation are completely correct; when I rebuilt our fridge I added LOTS and its now possible for the whole thing to become a freezer if you accidentally knock the thermostat.

The evap' in the fridge is one of these:

http://www.penguinfrigo.co.uk/product_images/307-1-l.png

and the only mistake I made was not getting one with a door so the inside of the evap' can be used as a freezer compartment. I built the whole thing and it all worked first time.

The whole system is very economical on electricity usage and is very good at chilling down the whole fridge compartment. Just bear in mind what everyone says about insulation being just as important!
 
we had a frigoboat keel cooler on our last boat that I installed. It used a 2.5 amp compressor that averaged out at approximately 1 amp consumption as it ran the compressor so little. the keel cooler worked ok when we dried the boat out it just used more electricity as the condensing temperature elevated. Dont paint the bronze keel cooler. it does get one or two barnacles on it but a scrub with a brush a couple of times a year clears them fine.
 
"Permeable sintered" was more or less lifted straight from the technical description provided by Frigo. I think it basically means a matrix of bronze with the copper pipe embedded in it. The whole unit is about the size of a standard hull anode.

I would be buying one of their cabinet fridges so insulation will be predetermined by Frigo. If consumption is only about an amp then that is about a sixth of what our current unit draws.


JSYmartini said:
I am looking at fitting a freezer and keel cooling seems to be so effective I was wondering if I could also run my existing fridge off the same cooling unit if it was specced high enough. Not quite worked that one out yet.
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My understanding is that you need connection points on your compressor to allow for a remote condenser. Whilst you could probably adapt your existing compressor it would be costly no doubt. I can't see why one compressor couldn't run two units though. Most household fridge/freezers share a single motor these days.
 
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"I can't see why one compressor couldn't run two units though"

It could but you will need valves to direct the refrigerant to the requires unit with potential auto top up units to ensure the right amount of refrigerant in each section.

Mush easier to have 2 independent compressor circuits and simply witch the compressor's on and off when needed.


I also have a frigoboat separate fridge and freezer with keel coolers and I find that do work OK when out of the water between tides.
 
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William_H said:
I am wondering what "permeable sintered nature " means. I sort of assumed that the keel cooler would be a simple copper pipe running parallel to the keel and protruding from the hull fore and aft with the hot gas in it.
Click to expand...

About right...

299-2-l.png


The 'block' around the pipe is sintered bronze(?) type metal. Got one, and it works well, even if I've forgotten to switch the fridge off when drying out.

Mustn't paint the block, or scrub it too hard with a wire brush.

I saw an interesting suggestion recently (on here, I think) of mounting one of these in the fresh water tank instead of through the hull, in order to i) avoid another hole in the hull and/or ii) maintain cooling when dried out.
 
Thanks to all for telling me about the keel cooler. I am amzed at how small it is but apprently able to get rid of a lot of heat. I imagine the pipes to the keel cooler would also aid in cooling. Thanks again olewill
 
The keel cooler certainly seems to be the most efficient option, but it is expensive adding around £400 inc VAT to the cost and of course some extra work in fitting.

I spent some time talking to the helpful chap on the Penguin stand at SIBS and he persuaded me that for a small fridge, such as I am hoping to build this winter, there was really no point in going for the keel cooler. He said the fan on the compressor is very quiet and he doubted that we would notice any difference.
 
I used Rob Wells to fit mine. He fitted a standard compressor and they when I had the boat lifted he came back and fitted the keel cooler. This meant I didm;'t have to wait until the boat was lifted to get going. If you want his mobile or email address PM me.
 
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Been doing a lot of research on this as replacing my Peltier unit is one of my winter projects.

General consensus from all the suppliers that I spoke to was that water cooling was more efficient but not strictly necessary for Northern European waters.

As others have said, elimination of drain to bilge, compressor below waterline, well ventilated and as much insulation as you can get round the box seem to be the path to success.
 
I have a fridge and a freezer running on theses keel coolers. Definitely worth their inclusion due to reduction in power needed for the fridge.


By the way if you are testing you fridge for cooling and power consumption - make sure that you check the temperature setting as well. When I worried about excessive cycling of my fridge, I suddenly realised tha this large fridge was freezing into a large block of ice because some numpty (me!) had not noticed a thermostat set at -30C

Doh
 
Interesting adjunct to this thread. From a conversation with the dealer this morning, it looks like you can buy the standard air cooled version with connections (£60) to allow for later upgrade to keel cooler. When you upgrade you connect the keel cooler and just disconnect the air fan but leave the air based condensor in the circuit. This means that if you are out of the water you can reconnect the fan and revert it to air cooling with the keel cooler still attached. The best of both worlds.
 
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