Boat refrigeration insulation gotcha for Australians (and maybe some others)

[mako]

Originally Posted by GILow

So, if you are an Aussie...

And don't forget to install the insulation upside down.

Gosh, I really don't understand how you guys can go all day long standing upside down like that

[mako]

BTW, has anyone ever determined if there is really any practical advantage to installing additional insulation board around the sides/top of today's high efficiency A+++ refrigerators?

[RaymondR]

Originally Posted by makobuilders

And don't forget to install the insulation upside down.

Gosh, I really don't understand how you guys can go all day long standing upside down like that

Up and down are arbitrary constructs made when we did not know much about the cosmos but if you look at it from a galactic viewpoint we, down in Australia and New Zealand, are right way up and you folks in the northern hemisphere are all emulating sleeping bats.

[GILow]

Originally Posted by makobuilders

BTW, has anyone ever determined if there is really any practical advantage to installing additional insulation board around the sides/top of today's high efficiency A+++ refrigerators?

I don’t know, but I assume it would follow the laws of diminishing returns.

[Buzzman]

Originally Posted by Mr B

Why build your own fridge freezer unit,
RV Award stores, Bunnings, Tentworld, 4 x 4 shops, Etc Etc, all have huge Freezer, Fridge units for sale off the shelf,

12 Volt, 12 and 240 volt, 12, 240 volt and LPG, units, Some are 24 volts as well,
All Plug and play,
If you can get one thru your door, A lot of boats are putting in Domestic Fridge Freezer units, Upright and chest freezers,

It must be a Victorian thing, We can get them here,

The reason for DIY as opposed to off-the-shelf chest-type models is that the insulation is inadequate and thus excessive amp draw results.
As boats tend to have limited charging capacity (without running the main engine) this is an issue.

Chest fridges such as Engel et al are technically 'vehicle fridges' and rely on the A/C of the vehicle to keep the ambient to a minimum during the day. Turn off the engine (and therefore the A/C) and internal temps can reach 90degC. This results in puddles of flavoured cream (formerly ice-cream) and warm beer.

Boats generally don't have the luxury of the ICE powered A/C to reduce ambient, so extra insulation prevents runaway temps in the first instance.

Ask anyone who's used an Engel in a boat in FNQ.....

[Mr B]

Originally Posted by Buzzman

The reason for DIY as opposed to off-the-shelf chest-type models is that the insulation is inadequate and thus excessive amp draw results.
As boats tend to have limited charging capacity (without running the main engine) this is an issue.

Chest fridges such as Engel et al are technically 'vehicle fridges' and rely on the A/C of the vehicle to keep the ambient to a minimum during the day. Turn off the engine (and therefore the A/C) and internal temps can reach 90degC. This results in puddles of flavoured cream (formerly ice-cream) and warm beer.

Boats generally don't have the luxury of the ICE powered A/C to reduce ambient, so extra insulation prevents runaway temps in the first instance.

Ask anyone who's used an Engel in a boat in FNQ.....

Thank you for your reply, It was a genuine question, Wanting a genuine reply,
I have a Dometic fridge freezer, Upright model, on my boat, LPG and 110 volt, 90 litres I think it is,

In 30 Celcius outside temp every day, Fiji and Vanuatu, Etc, It kept my Food frozen to minus 18 Celcius,
The fridge kept my food and beer at +1 Celcius where I like my beer kept at so I can drink it,
I used LPG when I was travelling, But because of the difficulty and cost of gas certificates in Victoria,
I swapped my fridge to 110 Volts off a 240 volt Transformer out off my 240 volt Invertor from the 12 volt battery,
It Runs off my 500 watts of solar Panels and wind generator,
The 200 amphr AGM battery handles it quite well, I havent run out of power yet to run it on 110 Volts,

I do want to put a bigger chest type freezer on my boat, For the longer trips, Im Only Restricted by door size into the boat,

Failing that, I would use commercial fridge panels that come in 2, 4 and 6 inch thick panels, And buy a 12 volt freezer compressor to fit it,

Commercial fridge panels are foam sandwiched between two aluminium sheets, Thats what all the big industrial freezers are,
,
Thanks for the heads up on the Engel, I didnt know they couldnt hack the pace,

Cheers, Brian,

[GILow]

Originally Posted by Mr B

...

It Runs off my 500 watts of solar Panels and wind generator,

The 200 amphr AGM battery handles it quite well, I havent run out of power yet to run it on 110 Volts,



.....

Thanks for the heads up on the Engel, I didnt know they couldnt hack the pace,



Cheers, Brian,

Brian, although you say the 200AH AGM battery bank does handle the current setup ok, you might be a bit surprised (and dismayed) by how much power is being used for such a small device. You really want to measure the actual power it uses (there are plenty of cheap and reasonably accurate power consumption measuring devices available).

Some of those little portables use more power than a well made built in fridge with four or five times the volumetric capacity.

[Mr B]

Originally Posted by GILow

Brian, although you say the 200AH AGM battery bank does handle the current setup ok, you might be a bit surprised (and dismayed) by how much power is being used for such a small device. You really want to measure the actual power it uses (there are plenty of cheap and reasonably accurate power consumption measuring devices available).

Some of those little portables use more power than a well made built in fridge with four or five times the volumetric capacity.

Thanks GIlow, My fridge isnt a portable, Its a built in unit,

It runs on a gas, like the old Kero fridges did, It doesnt have a compressor in it, Im not sure what the 110 Volts actually do in my fridge,
But it does work very well, And uses very little power to run it,
The transformer and Invertor would use more power than the fridge does,

A new freezer unit would have a compressor, If I built it myself,

[GILow]

Those three way fridges use a heater element when on mains power. Horrendous power consumption.

The physics are interesting though...

https://en.wikipedia.org/wiki/Absorption_refrigerator

Easy enough to work our how much power it uses, just put a meter on either the feed to the inverter or the inverter output.

[FlyingScot]

Originally Posted by Buzzman

...

Chest fridges such as Engel et al are technically 'vehicle fridges' and rely on the A/C of the vehicle to keep the ambient to a minimum during the day. Turn off the engine (and therefore the A/C) and internal temps can reach 90degC. This results in puddles of flavoured cream (formerly ice-cream) and warm beer.
....

My Engel 40 sits outside under the cockpit table in the Caribbean and it will easily keep any temp I set up up to 85F below ambient. I normally run it at 31-32F for very cold drinks.

I don't feel that it uses excess power. Heck it only consumes 3 amps while running.

[GILow]

Originally Posted by FlyingScot

My Engel 40 sits outside under the cockpit table in the Caribbean and it will easily keep any temp I set up up to 85F below ambient. I normally run it at 31-32F for very cold drinks.



I don't feel that it uses excess power. Heck it only consumes 3 amps while running.

Yes, but what is the duty cycle? If it is 50% then that’s 36 AH in 24 hours which is close to the power used by a well made 200 litre fridge.

[Mr B]

Originally Posted by GILow

Yes, but what is the duty cycle? If it is 50% then that’s 36 AH in 24 hours which is close to the power used by a well made 200 litre fridge.

Thats the problem, A 200 litre Fridge wont fit thru the door, Bugga,

[RaymondR]

Originally Posted by GILow

Those three way fridges use a heater element when on mains power. Horrendous power consumption.

The physics are interesting though...

https://en.wikipedia.org/wiki/Absorption_refrigerator

Easy enough to work our how much power it uses, just put a meter on either the feed to the inverter or the inverter output.

In my childhood I lived in a town with wooden houses. One of the biggest sources of fires destroying the houses was kerosene absorption refrigerators. To get the pressures where they need them to make the absorption process work efficiently they have a cushion of hydrogen mixed with the ammonia and exploding fridges, whilst not common, did sometimes occur and result in a burning house.

[FlyingScot]

Originally Posted by GILow

Yes, but what is the duty cycle? If it is 50% then that’s 36 AH in 24 hours which is close to the power used by a well made 200 litre fridge.

My factory installed front loading spill-over 200 liter system consumes at least twice that per day. Probably closer to triple.

We are fortunate to make 400+ amp-hours per day.

[Cadence]

Depending on the size of an absorption unit the AC requirement is no more than a heat tape.