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Thread: Marine Refrigeration

  1. #1
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    Default Marine Refrigeration

    I'm planning on building a 12v. chest refrigerator and am wondering if Nigel Calder's book on the subject is still relevant. Any other sources or recommendations would be most welcome.
    Thanks,
    Doug

  2. #2
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    Default Re: Marine Refrigeration

    Richard Kollman http://www.kollmann-marine.com/ wrote the book on fixing and repair. Building boxes is not difficult. Most people are using 3-4" insulation. You can buy lids and frames. No drain if there won't be ice in the chest. Rparts was a good source. http://www.rparts.com/gallery.php?os...8t14afa5c76hg6

    I installed a 12 volt unit by Norcold and from Defender marine supply which I got on sale last summer. works great!

    Will it be a single box. or divided? (freezer and refridge)

    I can offer you some help, since I've been in the HVAC biz most of my life.

    Good luck!
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...58#post3996158

  3. #3
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    Default Re: Marine Refrigeration

    Between Calder and Kollman you'll have the topic pretty well covered.

  4. #4
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    Default Re: Marine Refrigeration

    Denise
    thanks for the reply. I want to build a semi-portable unit that can also be used in the van when we go camping. You bring up the one question I have: how do you make a refrigerator/freezer with the Norcold conversion unit?

  5. #5
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    Default Re: Marine Refrigeration

    Oh doug.. why don't you just get one that's already portable? Most any of the units will make freeze temps, the box is set up as a freezer with spillover cooling the fridge side. Just like a home side by side type. Some people use a small fan or sliding damper to control the air flow from on side to the other.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...58#post3996158

  6. #6
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    Default Re: Marine Refrigeration

    Denise,
    my wife had the same response, but it seems like a no-brainer to me. The conversion units can cool a greater volume than the cooler sized units, yet they cost about the same. I'm a cabinetmaker; knee deep in the needed materials. I'm going for it. So..... make a divided chest . How do I determine the the sizes ? will Calder or Kollman tell me this stuff?
    Doug

  7. #7
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    Default Re: Marine Refrigeration

    Doug,
    If you look up units they will give you cu ft they suggest. You realize the 12volt power needed is way more then just the single battery in a van? Most boats have at least 2, 12 volt batteries providing amp hours enough to go overnight without a recharge. 3-5 amps is an approximate load when they are running.

    Norcold http://www.thetford.com/HOME/PRODUCT...5/Default.aspx
    401278_t.jpg

    Waeco makes a compact "through the wall type that could work on DIY box too.
    http://www.defender.com/product.jsp?...6418&id=323775
    401988.jpg

    Thing is, the compressors don't like being knocked about.. in a boat the motion pretty benign.. Not like bouncing around in a truck. Again..more power then one 12 volt battery is needed in most all of them
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...58#post3996158

  8. #8
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    Default Re: Marine Refrigeration

    Thanks for the advice, Denise. I had not seen the Waeco unit (they recommend it for RV and truck use) it looks llike the way to go. As for power; the boat has a large house bank. I will add a second deep-cycle battery and isolater to the van.

  9. #9
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    Default Re: Marine Refrigeration

    I'd be interested in seeing the build of this unit if you're willing to share it. I've been looking at buying an off the shelf 12V/24V/240V unit for my H28, something like a WAECO 50ltr unit, but would like to see how you go about building your own and what sort of cost comparison there might be.
    Larks

    "Be who you are and say what you feel...
    Because those that matter...don't mind...
    And those that mind.... don't matter."

    LPBC Beneficiary

    "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great!"

  10. #10
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    Default Re: Marine Refrigeration

    In the end, insulation of the box is the key. The more, the better. Gaskets count as well.

    After a lot of research I bought an Isotherm unit, but others will be fine if your box is insulated to the max. Vacuum panel are best and also expensive.

  11. #11
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    Default Re: Marine Refrigeration

    I have an Engel 15. It works well. It's quite portable and has a carrying strap. It draws 3 amps at 12v dc when running. It runs continuously for about an hour to cool down then runs about 50% of the time to keep cool. Thus it uses something like 50 amp hours per day. So I have to run the engine to charge the battery each day.

    My unit is similar to this: http://www.buyengelcoolers.com/engel...e-freezer.html

    I used it in my truck once for a long trip and was happy with it so long as I didn't plan to leave it all day.

    The Engel can freeze though I haven't tried it.

    If I build a reefer like the OP is considering one of my goals will be to get it to run with less than 3A.
    Will

  12. #12
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    Default Re: Marine Refrigeration

    Quote Originally Posted by willmarsh3 View Post
    I have an Engel 15. It works well. It's quite portable and has a carrying strap. It draws 3 amps at 12v dc when running. It runs continuously for about an hour to cool down then runs about 50% of the time to keep cool. Thus it uses something like 50 amp hours per day. So I have to run the engine to charge the battery each day.

    My unit is similar to this: http://www.buyengelcoolers.com/engel...e-freezer.html

    I used it in my truck once for a long trip and was happy with it so long as I didn't plan to leave it all day.

    The Engel can freeze though I haven't tried it.

    If I build a reefer like the OP is considering one of my goals will be to get it to run with less than 3A.
    I'm pretty sure it would have to be small or have to go with 24 volts. Engel and norcold use a "swing type compressor" many others do but the better knowns like sea frost use the Danfoss compressors that are traditional piston types
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...58#post3996158

  13. #13
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    Default Re: Marine Refrigeration

    I found that a small inverter of 750watts easily runs a normal fridge. Pick the size you want with an energy star rating and wire the inverter to the battery bank. Its by far the cheapest most effective way to go. I doubt you will get the amount of insulation in a homemade unit that the Danby guys can get with sprayfoam. Those little bar fridges work pretty good and can be put in a truck as well as a boat.
    If you bolt the inverter to the fridge you just have to wire in a 12v plug to where its going to live in each vehicle
    Freudian slips : when you say one thing but mean your mother.

  14. #14
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    Default Re: Marine Refrigeration

    Quote Originally Posted by Soundman67 View Post
    I found that a small inverter of 750watts easily runs a normal fridge. Pick the size you want with an energy star rating and wire the inverter to the battery bank. Its by far the cheapest most effective way to go. I doubt you will get the amount of insulation in a homemade unit that the Danby guys can get with sprayfoam. Those little bar fridges work pretty good and can be put in a truck as well as a boat.
    If you bolt the inverter to the fridge you just have to wire in a 12v plug to where its going to live in each vehicle
    How big is your battery bank?

    It looks like this might work well.

    According to this: http://www.designerappliances.com/danby-dar195bl.html

    309kwh/year works out to an average current use of just less than 3 amps at 12 volts dc. When it breaks just swap in a new one.
    Will

  15. #15
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    Default Re: Marine Refrigeration

    call it 5amps on average with losses. these lil fridges draw less than 5 amps of 120volt and if they are unopened they will cycle about 10% of the time. that would work out to about 5amps of draw every hour of 12volt. Inverters are only about 80% efficient. Still not a bad draw on a battery bank. Now if only they made one that was a little better looking
    Freudian slips : when you say one thing but mean your mother.

  16. #16
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    Default Re: Marine Refrigeration

    Quote Originally Posted by Soundman67 View Post
    call it 5amps on average with losses. these lil fridges draw less than 5 amps of 120volt and if they are unopened they will cycle about 10% of the time. that would work out to about 5amps of draw every hour of 12volt. Inverters are only about 80% efficient. Still not a bad draw on a battery bank. Now if only they made one that was a little better looking
    That's roughly four times the drain we see on a marine 12-volt refrigerator. 110 v. units tend to be inefficient, even before the inverter losses are factored in.

  17. #17
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    Default Re: Marine Refrigeration

    http://www.ohmslawcalculator.com/ohm...calculator.php


    Yall may be surprised to see how many amps a 5 amp 120 volt fridge draws on a 12 inverter.

    jus sayin...
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...58#post3996158

  18. #18
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    Default Re: Marine Refrigeration

    Yep. And you better have 20-30 percent more capacity than required available for the surge when the compressor kicks on.


    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

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