AC residential freezer on board?

[rwidman]

One of Gray Hawk's previous owners has a domestic freezer on his current Defever. He uses it on regular trips to Alaska. He has disconnected the thermostat so that, when powered, the freezer compressor runs nonstop. His theory is that he gets the freezer "really cold" and then it holds longer when its not running. Anybody here have any experience with that practice? .

That sounds like a pretty dumb idea to me. If a thermostat wasn't a good idea, the manufacturer wouldn't have installed one. There's a point where continued running won't get the freezer any colder, it will just wear out the compressor.

I once had a boss like that. He "didn't believe in thermostats". He set the AC system thermostat to 65 degrees, then cut it on untill he was comfortable, then cut it off until he was hot, then turned it on again. It was uncomfortable for the rest of us and nobody could convince him that the thermostat was doing the same thing automatically.

 

[Codger2]

I once had a boss like that. He "didn't believe in thermostats". He set the AC system thermostat to 65 degrees, then cut it on untill he was comfortable, then cut it off until he was hot, then turned it on again..

Wait a minute! Are you talking about my wife?

 

[Daddyo]

Wait a minute! Are you talking about my wife?

 

[psneeld]

I guess it would be a good idea if the freezer thermostat had a lower limit...if it did it would make perfect sense to get rid of the stat. Manufacturers make things to price points and for the masses..,not for the smart and creative...

Does NASCAR accept factory autos or do they soup them up????...do airplane racers take factory aircraft stock and race them????? Do snipers live with factory ammo????

I could go on and on but the vast majority here already know...

Anyone that has to live with what maufacturers produce get exactly what they deserve.

That said...sometimes it's the best that can be done for the price point, but often it's not...you just have to do a little research and use your brain to know when to get a little creative...

 

[bobofthenorth]

Anyone that has to live with what maufacturers produce get exactly what they deserve.

That said...sometimes it's the best that can be done for the price point, but often it's not...you just have to do a little research and use your brain to know when to get a little creative...

That's kind of how I was thinking too. I think Chuck puts a thermometer in the freezer to monitor the temp. It seems to me it would make a lot of sense when you're anchored to have it run hard while the gennie is running. It wouldn't take long to figure out that it gets down to XX degrees and never goes any lower so at that point you could just unplug it.

 

[Tidahapah]

I run a domestic frig and a freezer on Tidahapah. Both LG 90 lt units. The frig all frig so that there is no freeze section.
I also have an Eva Kool 110 lt frig and a 110 lt freezer on the back deck (these are similar to Waco Engel but in fiberglass boxes and made locally here in Aus)
All these run of my inverter over night and at other times when no 240 Volt power is available.

I have a 3000 Watt/24 V Victron Inverter charger and hve never had a problem with it. Master volt units appeared to give a lot of problems down here in Aus for some time.
The domestic frig and freezer have now been running continuously for just over 7 years now.
Benn

 

[BruceK]

I run a domestic frig and a freezer on Tidahapah. Both LG 90 lt units. The frig all frig so that there is no freeze section.
I also have an Eva Kool 110 lt frig and a 110 lt freezer on the back deck (these are similar to Waco Engel but in fiberglass boxes and made locally here in Aus)
All these run of my inverter over night and at other times when no 240 Volt power is available.
Benn

Ben, How much battery capacity, and what type, do you have to run those?
Do you sometimes run all at the one time?
What charging system(s) do you have, additional to the main engine?

 

[Tidahapah]

Bruce,
Myhouse bank consists of 8 Trojan T 105 6 Volt batteries set up as a 24 Volt system.
Capacity 450 Amp @ 24 V
Victron Inverter/charger has a 50 amp charger, my cruise alternator is 5 KVA and runs when I am at cruising RPM.
I also have a 9 KVA gen set
main engine only has a 60 amp charger
There is a 2 KVA Honda as an absolute back up if required.

My friges and freezers run all the time I am on board.
Cheers
Benn

 

[Dougcole]

great advice all around here guys. I'm leaning toward giving it a go with a small domestic freezer, something along the lines of 3 cf. It is tough to figure out how much they actually draw prior to purchase as those specs aren't readily available, but my thought is that the smaller the box the less it has to run.

There is a really great spot on the new boat to put it, a spot that is set up to hold a washer dryer (which we don't have). It will be well secured and wiring will be easy. On a top loading chest freezer you really don't need a door latch.

On our long Bahamas cruises it really pays off to have more freezer space as food is roughly 1/2 the price in the US as there. Also, my feeling is that you can use a freezer to make ice ("blue" blocks are easiest) which will then make fridge space using a cooler.

I have a 10 year old and a 14 year old son. We have to bring a lot of food.

 

[Soundwiz]

I have a "Holiday" 5 cubic ft freezer that I bought on line at Lowes. They delivered it the next day, all the way to my slip, unpacked and installed it
on the aft deck. It doesn't have a defrost mode, but after running continuously for 3mos haven't had to defrost yet. it does have a drain, and good seals on the lid.
It is on the aft deck and was exposed to weather for three weeks while my Bimini was being restitched. I'm very happy with it, holds more than I need and cost less than $200.00

Dopp

 

[rwidman]

............ It is tough to figure out how much they actually draw prior to purchase as those specs aren't readily available,.............

Current consumption should be on a removable label on the outside but if it's not, look for a label near where the power cord enters the unit.

 

[rwidman]

I guess it would be a good idea if the freezer thermostat had a lower limit...if it did it would make perfect sense to get rid of the stat. Manufacturers make things to price points and for the masses..,not for the smart and creative...

Does NASCAR accept factory autos or do they soup them up????...do airplane racers take factory aircraft stock and race them????? Do snipers live with factory ammo????

I could go on and on but the vast majority here already know...

Anyone that has to live with what maufacturers produce get exactly what they deserve.

That said...sometimes it's the best that can be done for the price point, but often it's not...you just have to do a little research and use your brain to know when to get a little creative...

Bypassing the thermostat is neither "smart" nor "creative". It's stupid. If you want the freezer to get as cold as it possibly can, set the thermostat to the lowest setting. Then you won't have the compressor runing and doing nothing.

 

[rwidman]

............... It wouldn't take long to figure out that it gets down to XX degrees and never goes any lower so at that point you could just unplug it.

Babysitting a freezer when the thermostat that's already installed would do the same thing? Doesn't make sense to me.

 

[koliver]

Our boat had a small AC freezer on the back deck in the broker's photos before we bought her (1994). In 96 or so I found a used DC freezer, 2 cu ft, that fit nicely beside the bed in the aft cabin. I don't know the brand name, (none showing) but it runs off a Dan Foss compressor like the one in our main fridge, so is quite economical on power. Its size is perfect for a three week vacation. By the time all the frozen food we have brought with us is used up, it has room for all the prawns and other seafood we have caught.

Friends run a small (maybe 5 cu ft) AC freezer off a small inverter. It has timers on it so it only runs when they want it to. They have developed an obsession to keep checking the battery power level, so I get the message that it is a giant PITA.

Go DC if you can.

 

[Papa Charlie]

Several of our neighbors have small AC, home style freezers on board. Most use an inverter to run the unit. But with new appliances and their PCB controls, it is important to use only a pure sine wave inverter. We recently replaced the old inverter with a Magnum 2810 with a built in 100 amp charger. With our flat screen tv's, computers, new AC frig and other electronics it was necessary to go with pure sine wave.

We love the Magnum and how well it performs. The remote is not as advanced as the Xantrex but I can live with that. But the inverter is, in my opinion, far superior.

The batteries supporting the inverter is as critical as the inverter, depending on your intended use and how often you intend to run your generator or have to find a dock to recharge. Running the mains without oversize alternators is not, in my opinion, a logical approach to recharging on a daily basis.

On our boat a lot of systems are run through the inverter including: Refrigerator, all outlets, water pressure pump, engine room lights, fluorescent lights throughout vessel and the microwave. The microwave runs fine on the inverter but we will be taking that circuit off the inverter as it draws a great deal of energy that is not required. We are able to go two days without recharging and it takes very little time with the generator and the 100 amp charger. When underway we occasionally will run the generator but it isn't critical as the starboard engine alternator is a 185 amp unit.

 

[caltexflanc]

They are required to tell you how many amps or watts they draw when running and in some cases when starting up. . Keep looking at specs or if shopping in a store there will be a label on the unit somewhere, usually in the back. As others have noted, the unit does not run all the time, depending on the exterior temperature and how often you open it up. A 5 cu ft GE uses 240kwh a year, or a little over 600 watts a day. 5 amps at 120v, 50 amps at 12.

A great accessory on a boat is a vacuum sealer. Many use beyond food, but really outstanding for freezing meats. fish and soups and you name it. For instance, we'd wait until we got some place with a Costco (preferably) or Sam's nearby, or the greatness of Penn Dutch, stock up on meat and vacuum it and freeze it. Makes a huge difference in how it tastes.

 

[Codger2]

A great accessory on a boat is a vacuum sealer. Many use beyond food, but really outstanding for freezing meats. fish and soups and you name it. For instance, we'd wait until we got some place with a Costco (preferably) or Sam's nearby, or the greatness of Penn Dutch, stock up on meat and vacuum it and freeze it. Makes a huge difference in how it tastes.

My brother and his wife cruised the Sea of Cortez & Central America for years. (30K miles) They considered the vacuum sealer and Costco as mandatory items on their outfitting lists.

 

[jeffnick]

I continue to play with my Danby 3.2 Walmart freezer and Freedom 30 inverter, although winter is not the best time to be evaluating run time.

Here's some bullet points:

A chest freezer doesn't let all the cold drain out when the door is opened.

By setting the freezer thermostat to max cold and using a remote bulb line thermostat (STC 1000 -- eBay ~$20) you can have the freezer maintain any temperature range you want even above freezing into the refrigerator range.

By freezing a 5 gallon brine brick in the freezer you can maintain a selected temp (depending on the amount of salt) in the unit for about a week without power.

After about a year of pretty good use on the road and on the water, my freezer quit, wouldn't even make ice. Rather than fixing it under warranty, Danby sent me a check for the full purchase price and I ordered another one, this time taking the 3 year WalMart warranty for an additional $20.

More here:

One More Time Around: Freezer/Refrigerator Findings

And I believe a search of the forum will turn up additional info.

 

[CPseudonym]

Jeff, thank you for turning me on to the brine brick procedure. I've shared your system with a couple friends of mine and we are all extremely satisfied with the results.

 

[jeffnick]

Jeff, thank you for turning me on to the brine brick procedure. I've shared your system with a couple friends of mine and we are all extremely satisfied with the results.

 

[FF]

The challenge is that many people do not want to opt for a good quality wired in inverter. They are not cheap.

A real sine wave inverter has more power to operate very heavy loads than the MS style.

Air cond , Scuba pumps and some water makers may require it.

A small undercounter freezer surely wont.

"Leveling" the fridge was a big deal in the 1970's with PROPANE RV fridge /freexers, today If today can stay in bed with out belting in that's close enough..

The biggest hassle with a home fridge is its power draw.
No problem with a power hose at dockside , but long hours required for most small units would kill most boat house batt sets.

Read the yellow tag on the new freezer , it gives KW required (in some gov dreamland Stepford) for a year.

Divide what ever annual number they claim by 360 and you will have KW required per day.

1 KW at 12 V is probably 120A to 150A from your battset that will need 150A to 175A of charge to refill. Good luck!

Probably a house freezer with a 2000W Honda on the back deck would be easiest to live with.

 

[rwidman]

.

Originally Posted by Dougcole
............ It is tough to figure out how much they actually draw prior to purchase as those specs aren't readily available,.............

For Dougcole, This is a photo of the label I was talking about. All appliances are required to have them. In this case, the third line from the bottom specifies the current draw, 1.2 amps (at 120 volts AC).

This is not the current that will be drawn by the inverter if you connect it to yur boat's batteries, that will be roughly ten times that anount or 12 amps DC. Since there is some loss in the inverter, I would round this up to 15 amps when figuring the battery capacity needed to run it.

The compressor will not run 24/7 (unless you bypass the thermostat like some folks have suggested) so the total current draw will be less in a day than the 360 amp hours per day that it would draw if it ran continuously.

The average run time of the compressor depends on the quality and quantity of insulation, the temperature setting of the thermostat, and the environmental conditions the appliance is kept in. It will run more if kept in the sun in Florida than if it's kept in an airconditioned space.

Before you decide this is the best option for you, compare the 15 (or even 12) amps DC to the current draw of 12 volt or "AC/DC) marine appliances. I think you'll find the marine appliances to be more efficient.

 

[Papa Charlie]

In my humble opinion the government energy stickers are not at all helpful. They make a lot of assumptions that I don't believe really apply to boating life compared to an average family at home. Boaters are generally more cautious about how they use things as power is not taken for granted.
Here in the PNW where ambient temperatures are not as high as Florida, we have friends that turn off their freezers while underway and only turn them on during there regular operation of the generator. As pointed out the chest type are more efficient and you are not opening them up that often. Add to that the suggested brine block and it could end up running very little.
As for the home style frig vs a boat type. There may be a little more energy draw when running than a boat style unit due to the fans inside that circulate the air, however, because the air is circulated around the food and the thicker insulation, you will will find that they run fewer times and for less time during each run.
You would have to hook up totaling amp meters, on similar size units, in like environments and open them approximately the same number of times to actually verify which unit uses more energy. Having owned both, and based on my battery drain, I would say there is little difference between the two as it takes X amount of energy to produce Y amount of cold. The compressors are basically the same and therefore, with all things equal, they should use approximately the same amount of energy.
One other factor that we have seen living on board. The 12v unit without the circulating fan did not preserve the food as well as the home style unit that produces even temperatures throughout the compartment and the air movement also reduces the amount of moisture. That means I had to dispose of less food before its time.
I think both systems are good. The home style unit requires a good inverter, which adds cost but it also runs many more systems so you would need to amortize the cost of the inverter over all systems. When we went to replace our frig I looked at both the 12VDC and the 120VAC and decided as live a boards the home style unit provided us better long term use benefits. Should our use be more recreational, I would have spent the additional money and purchased the 12VDC unit.
I think I ended up with a nice looking unit, it is energy efficient and preserves my food very well. Besides the Admiral likes it.

 

[jeffnick]

My expired 12vdc/120vac fridge ran at 28vdc no matter which power source was connected - so there is at least a small power loss factor with that model. It never ran well on 12vdc, even with a relay and #6 wires to the battery.

My new fridge is 120 only and will be powered by a dedicated battery via the Freedom 30. It's smaller than the takeout, but it doesn't have a freezer compartment so the I haven't lost any capacity - who uses that tiny freezer anyway?

Being a stand alone unit, it was also nice to have the extra space for ventilation, not to mention the thermostat knob is on the back of the unit and can easily be reached via the velcroed upper vent strip.

I didn't want to put holes in the new fridge so I used a wedge install.

The final version had a plate on top.

Interesting to note that the same 2.5 cf unit with a freezer section is rated at 329KWh and the non-freezer unit like mine is less at 309KWh per year. The 3.6 cf freezer I have is only 215KWh/yr...maybe cause it isn't rated to open as often -- or because it's a chest?

 

[FF]

Add to that the suggested brine block and it could end up running very little.

The energy requirement of any item, fridge , freezer or even a house depends on the outside surface area , insulation and temperature differential required.

A brine tank , eutetic fluid may hold the internal temperature stable longer (as the specific temp solution melts) , but it does not change the energy required to keep the temperatures different.

A eutetic setup will frequently allow the energy to be transfered at a time that is easier for the operator , but the total energy required does not change.

Steve Dashew sells fairly cheap recording thermometers.

If the temp bounce is large enough to defrost some food some time , months of storage becomes very dangerous.

 

[Papa Charlie]

Add to that the suggested brine block and it could end up running very little.

The energy requirement of any item, fridge , freezer or even a house depends on the outside surface area , insulation and temperature differential required.

A brine tank , eutetic fluid may hold the internal temperature stable longer (as the specific temp solution melts) , but it does not change the energy required to keep the temperatures different.

A eutetic setup will frequently allow the energy to be transfered at a time that is easier for the operator , but the total energy required does not change.

Steve Dashew sells fairly cheap recording thermometers.

If the temp bounce is large enough to defrost some food some time , months of storage becomes very dangerous.

It doesn't change the energy required to run the unit, however, it will effect how often the unit has to run and that will effect the overall drain on the battery system within a 24 hour period. As you are no doubt aware, fresh water freezes at 32 degrees F and salt water freezes at 0 degrees F. The lower temperature of the salt/brine block will aid in maintaining the temperature longer than just the mass of frozen food inside the box. Beyond that I think we are in full agreement.

I generally will operate my generator, while on the hook at least once a day. Even in the SF Delta area in California, I have found that a simple ice chest with a couple of blocks of ice, capable of keeping frozen food solid for at least a day. Granted, it was not placed in direct sun and was not a cheap cooler. But neither is the insulation in most chest freezers.

 

[rwidman]

A brine block, ice block, or even pre-frozen food will reduce the energy required to keep the freezer or refrigerator cold when away from shore power if it is frozen using energy from shore power.

Most of us don't concern ourselve a great deal with the unlimited energy provided by shore power (or a residence), but we must be concerned with the amount of energy we use when away from shore power. Once we leave the dock, our boats become pretty much self contained worlds as far as electricity, water, and sewage are concerned.

 

[FF]

"fresh water freezes at 32 degrees F and salt water freezes at 0 degrees F."

Not so, salt water freezes depending on the Quantity of salt in the water.

The engine driven eutetic systems use this fact to set the temperature the plate melts at , depending mostly on the quality of insulation in the system, and the size of the eutetic system.

On our 90/90 we operate in 2 different modes.

The freezer is next to the fridge with a thermostated vent between the spaces.

Living aboard the freezer plate (5500 BTU 0deg solution) is powered by shore power and the fridge gets cold via the vent.

For a weekend jaunt it is a fine solution.

Cruising a 4400BTU 20deg plate in the fridge side helps the freezer plate keep the box cold longer.

2 hours of engine time compressor is long enough to drive the 0 F freezer plate to about -15 F which assures it all is frozen.

With 6 inches of freon blown urathane the box will hold a constant 5 deg F for 3 days and on the 4th the temp climbs to about 15 F to help cool the fridge portion.

We move for 2 hours minimum every 3rd day when lazy cruising on our home turf.

Eutetic can provide TIME between power requirements , but it does not change the total amount of POWER required to keep refrigerated.

The eutetic system is expensive in terms of initial system cost ,+ a custom box with thick walls , + the space required inside the insulated box to hold the plates, + a mount for the compressor on the engine.

The upside of frozen food month after month , in SILENCE, with no dead batteries and the coldest beer this side of the Siberia! is worth it to us.

 

[Papa Charlie]

I do stand corrected on the temperature salt water will freeze. According to a Google search:

"The freezing point of salt water varies depending on how much salt is in the water. For example, water that is 3500 parts per million salt (avg. amount in seawater) will freeze around -2 degrees Celsius (28 degrees F). Water with an extreme amount of salt in it, like in some lake waters in Death Valley CA, with 300,000 ppm, will freeze at -20 to -30 degrees C (-4 to -20 degrees F).

The degree Fahrenheit (°F) is a unit of temperature named for the German physicist Gabriel Fahrenheit (1686 - 1736). In the Fahrenheit scale of temperature the freezing point of water is 32 degrees and the boiling point is 212 degrees, placing the boiling and melting points of water 180 degrees apart. Zero degrees Fahrenheit indicates the lowest temperature Fahrenheit could obtain by a mixture of ice and salt.
That depends on a number of factors including the concentration of salt in the water and the type of salt in the solution. Sodium Chloride (NaCl) can exist in aqueous (water-based) solutions with concentrations ranging from 0% to about 23% by weight. The maximum concentration, which corresponds to the saturation point for the solution, is dependent on temperature. The freezing point for a 23% NaCl solution is about -21 degrees C".

 

[FF]

For those that are building a eutetic plate , or just filling a couple of jugs to help out holdover , salt is the preferred material.

Anti freeze will work but takes up more "room" in the eutetic tank leaving sless space for water.

This also works at higher temps , the less antifreez in a non or low pressure cooling system , the more water , the better heat transfer.