Conference vicki::boats

    They are NOT fairly cheap! A small AC/DC Refer goes for $400. - $500.
    
    

    I' agree with .1 they ar NOT cheap, but i think 4-5 is on the low side,
    
    i would say 5+ is more in line with what they cost..
    
    JIm

Maybe this person's income allows him to think of these prices as cheap.

Not all boat oweners are poor. Some actually can afford these things!

jlg

    yeah, at Sears $500 will get you a full size fridge instead of the
    .00002 cu ft marine type.
    

    Walk by the docks of any sportfishing center and it makes you
    realize how many people can really afford these things.
     
    Keeps me dreamin...
    
    Mr mod you can delete or move this dribble if you wish.
    
    Bruce

    
    Problem solved....the frig just needed a re-charge and works fine now.
    Judging from the responses on my initial request for help I guess not
    many folks have had problems with boat AC/DC frigerators before as the
    only comments received were regarding my statement that these things
    were relatively cheap. I had been told that a new one was about $250
    and from my standpoint it potentially wasn't worth sticking a lot of
    bucks in the old one if new ones were about $250. It's a moot point at
    any rate, but I also learned something....Apparently if these small
    frigerators sit for an extended period of time (not in use) they will
    lose their charge. Where it goes I don't know, but that's what the
    repair folks said. Maybe they're blowing smoke, but no leaks were found
    under a U.V. test process; just needed a charge...this after 2+ years
    of in-activity........
    
    steve

I had a similiar problem with a home refrigerator that was allowed to sit in my
cottage over the winter with the plug pulled. It wouldn't cool in the spring.
The repair person had a similiar diagnosis, said this particular model didn't 
like to sit. (Which is stupid because it was exactly the type that would be 
bought for seasonal use). It was under warranty so I was able to return it and
get a newer, different, and better model.

And it cost more than a standard fridge (I couldn't use one, they are too big)
too. I think that special sizes (whether boat or cottage) cost more to make than
the standard ones that are mass produced by the 10s and 100s of thousands.

jlg

    
    One of the reasons the marine refrigerators and camper refrigerators
    costs more is that a large number of them us ean ammonia/absorption
    cycle and do not use a compressor- similar to the old Servels. they
    become limited production and therfore expensive.
    
    
     The marine type refigerators that use compressors usually have a 110v
    ac/12vdc compressor- again very expensive because of complexity and low
    production volumes and a high mark-up distribution channel, amd limited
    competition.
    
     Try getting a propane refigerator of a decnt size- a 9 cu ft runs
    about $1200!- but you do not have many choices when you do not have
    electricity- such as my summer home on a small island.
    
    Dick

    Could someone offer a brief explanation of how a propane
    refrigerator works?  Intuitively, it seems silly.

    I guess if there were a MR_WIZARD conference, I should ask
    there...

    Thanks.

    
    The propane refrigerator uses an ammonia (not the household kind- the
    real bad, hazardous material kind) solution. When you heat the stuff,
    the ammnia vapor boils off (hot vapor),and the liqiod (hot also )
    become lean , or a dilut soltion. Both the hot gas and hot liquid rise
    through separate plumbuing and they are cooled (finned tubing- like
    baseboard heat) the coll gas and liquid then decide they like each
    other very much and want to get back together. The plumbing brings the
    two together and it takes heat to get them together. This is called the
    heat of absorbtion, as the gas is absorbed into the liquid. the
    solutuion cools (like WAY low!), and you have a refrigerator. The
    solution dribbles back into the main chamber and the process starts all
    over again. 
    
     Within limits, the more refrigeration you need, the higher you turn
    the flame. 
    
    Real simple, no moving parts.
    
    Problems:
    
    1. Anhydrous ammonia is very dangerous (it will kill you)
    
    2. Very high pressures are used- up to 800 psi
    
    3. Very slow response to load changes(like adding a bunch of heat in
    the form of 4 trays of water for ice cubes.)
    
    4. Exhaust can be hot (one of my rug rats put a box of crackers on the 
    back of my old Servel refrigerator- right where the exhaust came out-
    we kept smelling somethin funny until we realized the box was
    baked-like in burnt to charcoal!)   
    
    5. Expensive
    
    6. Expensive and difficult to repair- onlya few firms will even do it
    because of the ammonia/high pressures/special equipment
    7. Available only in small capacities.
    
    Advantages:
    
    1 Very efficient- it costs me a bout $45 worth of propane to run two
    old , poorly insulated Servels from April-Sept. The newer ones would be
    less than that.
    
    2 Quiet- sounds like a coffe pot perking away in the distance
    
    3 They last forever- last year I sold a 1927 and a 1932 servel- thetwo I
    have now were built in 1947 and 1952.
    
    4 They can run off any source of heat- propane, natural gas, 110v heating
    coil, 12v heating coil- I have even seen one with a kerosene burner!
    
    
    Dick
    

    If you want a reefer for lots less money in your boat may I suggest the
    following. The eastern block is selling a whole family of small coolers
    for dirt cheap. 2cuft about $80 6-8 cuft about $130 and 10 cuft $160
    Most of them seem to be made in Yugoslavia but I've seen some from 
    Hungary. You have three ways of generating the 110 VAC for them.
    1) Build a dynamotor from surplus or other parts. Since the small boxes
    probably only need a couple of hundred watts a 1/4 horse motor on a 
    20 Amp pipe would do it. The thermostat in the refridge would have to
    switch on the dynamotor and provide a delay to allow switching the AC
    only after voltage was up to avoid smoking the compressor. Other than
    that no special circuitry would be required. 2) Buy a switching DC/AC
    converter for about $250 new, for a several hundred watt unit. Build a 
    converter. If your good with magnetics wind you own torroids and build
    a switcher. If not drive a simple AB push/pull amp with a 60 hz
    oscillator and push the output through a 1 to 10 xformer that can
    couple a few hundred watts. Kind of heavy but could cost less
    than a hundred bucks if you don't have to buy a new xformer.
                                                                 

    
    RE: .12
    
    Geez, if I'd known it was that easy I'd have installed a fridge
    years ago....    8^)
    
    Rick

    Do I note just a tinge of sarcasim in your voice oh nautical
    compatriot?? 

    
    I guess you could read it that way if you missed the smiley face,
    which meant the reply was not to be taken seriously.
    
    You've gotta admit, your method of saving a few (or several) bucks 
    is beyond the scope of your average non-engineer type boater.
    
    Just curious, what would your insurance company have to say if a
    homemade non-UL or Coast Guard approved refrigeration or power
    converter system started a fire on your boat?
    
    Rick

    Being an EE and a tinkerer from way back I instinctively think of ways
    to build expensive gadgets from materials found around the home. 
    Interesting point about CG and UL approval, look at the insurance
    policy and see if its a requirement. I can't imagine a dynamotor
    starting a fire if designed to 130% peak load and with a thermal
    overload protector and current limiter connected to the alternator.
    I'd be a hell of alot more concerned about gasoline engines in
    enclosed spaces and 800 psi anhydrous ammonia in my cabin to tell
    you the truth. Commercial DC to AC swithing convertors are similarily
    protected BTW...