Fridges (again)

[Gibbo]

Those of us with electric fridges know that they are probably the biggest drain on power. Those with gas fridges don't have this problem. But some of us with electric fridges won't consider a gas fridge. This group includes me who lost a friend as a result of CO from a gas fridge.

 

But they are a pain for power. So here's what I'm contemplating..........

 

A good quality cool box. A small freezer (maybe very high power) only running when the engine is running. Fill it with cool packs. Use the cool packs in the cool box.

 

Anyone done anything similar?

 

Gibbo

[Speedwell]

Think of all the food/beer space you're using up ! Best I can manage is to turn the fridge to a high setting when moving and a low setting when stopped.

Arthur

[grahoom]

A good quality cool box. A small freezer (maybe very high power) only running when the engine is running. Fill it with cool packs. Use the cool packs in the cool box.

 

Anyone done anything similar?

 

A bloke who has a mooring near me (who also works on the farm that my mooring is on) does this. Although he uses the farmers freezer to freeze his cool packs.

[carlt]

Those of us with electric fridges know that they are probably the biggest drain on power. Those with gas fridges don't have this problem. But some of us with electric fridges won't consider a gas fridge. This group includes me who lost a friend as a result of CO from a gas fridge.

 

But they are a pain for power. So here's what I'm contemplating..........

 

A good quality cool box. A small freezer (maybe very high power) only running when the engine is running. Fill it with cool packs. Use the cool packs in the cool box.

 

Anyone done anything similar?

 

Gibbo

I used to have a small 240v fridge that I filled the ice box and the salad box with Ice packs and alternated them, as the ones in the bottom thawed.

 

The fridge ran off a small inverter from a solar powered battery bank and, in the height of summer, required the generator or engine to be run once a fortnight, for a couple of hours.

 

In winter the fridge was a stainless box, in the unheated backcabin.

[Naughty Cal]

Think of all the food/beer space you're using up ! Best I can manage is to turn the fridge to a high setting when moving and a low setting when stopped.

Arthur

 

Thats exactly what we do. We have a 12V fridge. We dont use our small freezer compartment for food so fill it with freezer packs, turn the fridge onto full whilst cruising, then turn it down when moored up. The freezer packs then go into a cool bag with some chilled beers ready for drinks on the bank/cabin roof. You do have to remeber to restock the fridge though afterwards.

[WotEver]

Those of us with electric fridges know that they are probably the biggest drain on power. Those with gas fridges don't have this problem. But some of us with electric fridges won't consider a gas fridge. This group includes me who lost a friend as a result of CO from a gas fridge.

 

But they are a pain for power. So here's what I'm contemplating..........

 

A good quality cool box. A small freezer (maybe very high power) only running when the engine is running. Fill it with cool packs. Use the cool packs in the cool box.

 

Anyone done anything similar?

 

Gibbo

 

Well, Waeco make a fridge that does a kind of automated version of that - let's ignore their ridiculous pricing for the sake of this discussion Above the freezer box at the top of the fridge are a quantity (I think 12) of those blue cool packs that you mention. They're built-in and pretty, but that's what they are. When the engine is running a relay bypasses the fridge thermostat and puts the compressor into 100% duty cycle. This freezes the blocks. When the engine is stopped the relay drops out and the thermostat comes back into play, but the compressor doesn't need to run for an awful long time because the blocks will be keeping the fridge contents cold for a long time thereafter.

 

The disadvantage of this system is that the main fridge area gets down to very close to 0C (ideal minimum for a fridge is around 4C) and this can have a sub-optimal effect on things like tomatoes which don't like to be frozen.

 

I've been considering trying something along the same lines (but without the physical modification to the fridge of course) and incorporating a timer so that the relay only holds in for say 2 or 3 hours - experimentation and a thermometer should determine how long it takes to get the fridge down to say 2C.

 

Regards,

Tone

[BlueStringPudding]

Isotherm have the same technology in many of their fridges.

[Greybeard]

Off topic (but sort of related)

 

Not exactly the cheapest option http://www.solar2renewableenergy.com/prodd....php?prod=50LFR

 

It's 12v so could possibly adapted to run on the batteries some of the time perhaps?

 

Not my field at all so may be talking ****

 

Mike

[nb Innisfree]

Maybe an auto increase when cruising/charging, t/stat override when voltage exceeds a certain level, say 13v or 26v ?

[WotEver]

Maybe an auto increase when cruising/charging, t/stat override when voltage exceeds a certain level, say 13v or 26v ?

 

Two stats? Dunno how they're fitted or how practical, but one (set on 'miserly') for when there's no engine or hook-up and the other (set on 'super-chill') for the reverse situation sounds like a plan.

 

Anyone know anything about fridge stats? I've not even looked at the back of ours since we fitted a new one a few months back.

 

T

[nb Innisfree]

Two stats? Dunno how they're fitted or how practical, but one (set on 'miserly') for when there's no engine or hook-up and the other (set on 'super-chill') for the reverse situation sounds like a plan.

 

Anyone know anything about fridge stats? I've not even looked at the back of ours since we fitted a new one a few months back.

 

T

 

T/stat override would give 'super chill' I think that's all freezers have for quick freeze, t/stat could be set to 'miser'. In fact I think most fridge freezers have only one t/stat or used to don't know if that is different today

[WotEver]

T/stat override would give 'super chill' I think that's all freezers have for quick freeze, t/stat could be set to 'miser'. In fact I think most fridge freezers have only one t/stat or used to don't know if that is different today

 

Sorry, I wasn't clear - I meant add a second stat. I was trying to avoid the fridge getting below say 2C.

 

T

Edited June 23, 2009 by tony@hdheaven.co.uk

[ditchcrawler]

T/stat override would give 'super chill' I think that's all freezers have for quick freeze, t/stat could be set to 'miser'. In fact I think most fridge freezers have only one t/stat or used to don't know if that is different today

I don't think my fridge has a stat, I think it works on a timer. Its a 240 volt Lec and I can't find the stat anywhere. I did try turning it to max with the engine running and min when we stopped but of course it just cut in again after the set time and didn't save anything. I am considering putting it on a time clock and turning the stat/time to max so it only runs for short periods evening and night time with a long run in the afternoon to try and tie in with normal engine running hours.

[casper ghost]

Here's what my brother's planning to do on his new boat. Build a steel box direct onto the hull bottom and sides. Insulate the outside of the steel box. Place a 12v cool box motor in the bottom. The steel box will be cooler as next to hull and on hotter days you can cool more by using the cool box motor.. It must have ventilation though to prevent the food inside going off..

[Guest User]

In the past we adopted the cool box and icepacks technique on my GF's boat. For a week's cruising, we used a polystyrene box with 2" thick walls (the sort used for transit of chilled items) and filled with frozen and chilled food and only a couple of ice packs. The food was all intended to be eaten within the week so a gradual thaw of the frozen items was acceptable, we managed fine with this system, with the food staying good and chilled for about five days. It wasn't ideal but as a temporary solution it worked well enough

Edited June 23, 2009 by Graham!

[mrsmelly]

Those of us with electric fridges know that they are probably the biggest drain on power. Those with gas fridges don't have this problem. But some of us with electric fridges won't consider a gas fridge. This group includes me who lost a friend as a result of CO from a gas fridge.

 

But they are a pain for power. So here's what I'm contemplating..........

 

A good quality cool box. A small freezer (maybe very high power) only running when the engine is running. Fill it with cool packs. Use the cool packs in the cool box.

 

Anyone done anything similar?

 

Gibbo

 

Hi Gibbo

 

Like the topic, sorry to hear about your friend with the gas fridge. I have had 12v, mains and gas fridges and I think gas fridges are best though at present dont have one but surely in the uk more people are killed from electric shock than gas poisoning, this is why I allways question gas free boats as without doubt gas is better for cooking than lectric on boats and the amount of people who die from gas on boats is infintesimle. is this not the case ?

 

Regards

 

Tim

[Smelly]

OTH how much gas does a gas fridge use?

 

We've got an electric fridge so far, but I would consider swapping as they're no longer quite so frowned upon.

 

We change our 13kg gas bottle 3 times a year and 6 months out of a bottle over the winter while the fire's burning with two of us living aboard. We just cook on it.

 

Any ideas how much that would increase with a gas fridge of a domestic size (although I could size down...)

[Justme]

I am considering putting it on a time clock and turning the stat/time to max so it only runs for short periods evening and night time with a long run in the afternoon to try and tie in with normal engine running hours.

 

Thats what we do for the fridge & freezer. Set the timer for when max solar power is produced for both & the fridge gets short boosts after each active period like meal times. Doing this our daily consumption has dropped from the makers claims of well over 1kwh to 0.6kwh each. We also turn them on if running the genny. Plus the new fridge has a claimed rate of 0.4kwh so when it arrives we will see how it goes on 24/7 & again with the timer.

 

Freezers need at least 4 hours daily on fast freeze. Poss a little more for smaller ones.

 

Some people claim that using a timer cant reduce the power used. Well I say that daft.

 

The unit has a max draw of X watts. Times that by the hours YOU let it run for & that's the MAX wh that will get used. The trick is making sure the temps achieved are acceptable.

 

 

Justme

[CampinGazz]

There is something on some eco forums at the moment about using a small chest freezer as a fridge, you replace the freezer thermostat with a fridge one, and then the more powerfull compressor only has to run a very short time, with lots of off time, also helped by the greater insulation of a deep freezer.

 

some times they quoted was 90 seconds run time, hour off time, but i'm not sure i can believe that, the chest freezer is chosen so you dont loose all the cold air in it every time you open the door as you do with conventional upright fridges (cold falling to the floor, on an upright it falls out the door, chest is stays in there)

 

someone in the motorhome club i'm in is investigating it, he's got a large american Rv, and their 3 way absorbtion fridges use a lot of gas, but we are talking double side by side doors, with an ice maker type fridge thats 6 foot tall by 4 foot wide, typical american engineering where they want their motorhomes to be as well equiped as their houses.. hence built in coffee makers, built in blender bases in the kitchen worktops, 2 large air con units, couple of massive flat screen TV's and so on.

 

Anyway, if the freezer as a fridge thing works, he has plans to make up a lift up rack system of wire baskets, so you open the lid, then lift up the entire contents of the fridge to gain acces, he's looking into counter weighted contraptions, but knowing him he'll prolly end up with a couple of hydraulic rams operating the lifting mechanism like how his slide outs work (those extra 'rooms' that slide out the sides of RV's when parked up making them twice the width that they travel).

 

obviousely this is a mains compressor freezer, but for such short run times if it works that's not a problem to run off an inverter, prolly a dedicated small inverter that's switched on by the thermostat,

but like i say, it may turn out to be yet more eco b*ll*x, like those fridge sava plug things that allow a compressor to start up at full torque, then chops the wave form up to supply it reduced power, they were taken off the market as most modern mains fridges do that anyway, and trying to do it externaly messed them up,

i guess it's similar to how the danfloss compressors work by starting up slowly pulling an amp, and work upto full speed pulling 8 amps.

Edited June 23, 2009 by CampinGazz

[FadeToScarlet]

Thats what we do for the fridge & freezer. Set the timer for when max solar power is produced for both & the fridge gets short boosts after each active period like meal times. Doing this our daily consumption has dropped from the makers claims of well over 1kwh to 0.6kwh each. We also turn them on if running the genny. Plus the new fridge has a claimed rate of 0.4kwh so when it arrives we will see how it goes on 24/7 & again with the timer.

 

Freezers need at least 4 hours daily on fast freeze. Poss a little more for smaller ones.

 

Some people claim that using a timer cant reduce the power used. Well I say that daft.

 

The unit has a max draw of X watts. Times that by the hours YOU let it run for & that's the MAX wh that will get used. The trick is making sure the temps achieved are acceptable.

 

 

Justme

 

Well, my boat's got two 19kg gas bottles, because it used to have a gas fridge. It doesn't now, though, although the bottle size will probably tell you a lot about the expected consumption!

[Machpoint005]

... you don't lose all the cold air in it every time you open the door as you do with conventional upright fridges (cold falling to the floor, on an upright it falls out the door, chest is stays in there)...

 

You mean the warmer air can't get in quite as quickly. For the pedants, there is no such thing as 'cold', only less heat.

 

However, the important factor is for how long you leave the door open.

 

 

(edited for sppeeling)

Edited June 24, 2009 by Machpoint005

[smileypete]

Sorry, I wasn't clear - I meant add a second stat. I was trying to avoid the fridge getting below say 2C.

 

T

If you can get to the internal stat, a second stat may not be absolutely necessary. Just fix a smallish resistor to the tip/bulb of the stat and pass a current through it.

 

This will make the fridge 'think' it's warmer than it is, and switch on. With a bit of luck it might only need say 0.5W to drop the fridge temperature by a few degrees.

 

The resistor can be connected to the ignition/accessory feed, or even directly to the output of a solar array. With the right blocking/dropping diodes, it could be set up to boost fridge cooling when the engine is running, or the solar panels are getting bright sun.

 

cheers,

Pete.

[canalowl]

It may be worth having a chat to these people Dulas They have been manufacturing solar powered "cold chain" fridges for years. They seem to be extremely well insulated boxes with some clever electronics to make full use of the daily solar cycle. Adding our advantage of a huge heat sink (the shiny stuff) to dissipate the heat on the heat exchanger and they may be interested. Me I'm stuck in Dhaka for the next couple of years so its not something I could follow up. Dave

[KenK]

Those of us with electric fridges know that they are probably the biggest drain on power. Those with gas fridges don't have this problem. But some of us with electric fridges won't consider a gas fridge. This group includes me who lost a friend as a result of CO from a gas fridge.

 

But they are a pain for power. So here's what I'm contemplating..........

 

A good quality cool box. A small freezer (maybe very high power) only running when the engine is running. Fill it with cool packs. Use the cool packs in the cool box.

 

Anyone done anything similar?

 

Gibbo

 

Did exactly that when we took the car to Germany a couple of years ago, 12 V cool box three frozen cool packs, even leaving it turned off for an hour or so when on the ferry the cool packs were still frozen when we arrived. Capacity a bit limited so only room for essentials, beer and white wine basicly.

 

cheers

 

Ken

[Phil Ambrose]

I don't think my fridge has a stat, I think it works on a timer. Its a 240 volt Lec and I can't find the stat anywhere. I did try turning it to max with the engine running and min when we stopped but of course it just cut in again after the set time and didn't save anything. I am considering putting it on a time clock and turning the stat/time to max so it only runs for short periods evening and night time with a long run in the afternoon to try and tie in with normal engine running hours.

I think you will find the "thing " you turned to max is in fact the stat and not a timer, of course I could be wrong.