a few cruiseair AC questions

Discussion in 'OnBoard Electronics & Controls' started by sdowney717, Jul 6, 2012.

  1. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    a few cruiseair AC questions for an older system with rotary knobs
    I recently fixed my cruiseair 16,000 btu AC dual split system
    I recharged with HC22A and low is 70 to 75 and high 225 when it is 95 degrees outside.
    I must put the rubber insulating cover on the suction lines. This will make it more efficient and it also aids in cooling the compressor.

    It is back where originally installed sitting about 2 feet away from a HOT generator.
    It cooled the boat well, especially at night. We took boat out for the fourth and it was 100 degrees outside.

    A couple times the cruiseair compressor shut off, after the first time I opened the generator hatch cover to get more cooling for the area as I was worried about it overheating. Other time was returned to slip and gen set bogged down when microwave turned on and the cruisair shut off.
    Otherwise the cruisair ran fine on constantly for 24 hours.

    Is the location acceptable for the condensing unit
    or can this cause the compressor to overheat?
    If the compressor overheats does it have an overheat thermal shut off?
    It does have a high pressure cut off.


    I have read that the seawater must flow about 5 gallons per minute and the tube cleaned with muriatic acid this cools the compressed gas. I noticed the discharge water felt warm.
    The compressor is cooled by returned gas and ambient air which is why you should cover tubes with insulation. Should both suction and discharge tubes be covered with foam insulation?

    I am worried about the gen heat soaking the compressor.
    If I made a thick foam barrier pink or blue like 3 inch thick to shield the condensing unit from gen heat would this be worth doing?

    It would run from front to rear and mostly block the gen heat. Imagine a gen set and condensing unit sitting side by side in an enclosed space.
    What about an air blower in the lazarette?
     
  2. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Heat is definitely an enemy, systems that work fine in 80 degree weather fail at 90 plus heat. Fan is good idea, so is shield, but make it fire proof. Air has to circulate. But most important of all make cooling water is working right on AC and gender.
     
  3. MechaNik
    Joined: Jan 2011
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    Location: Greece, Italy

    MechaNik Senior Member

    Most compressors should have a thermal overload. But you should become familiar with the contacts in the control box, then you can find out what is shutting down the system.

    If it was already sitting close to a hot generator I doubt that ambient temperature outside will make much difference.

    "I noticed the discharge water felt warm" This is bad, discharge water should have a minimal temperature increase.
    Start by checking the water supply to the pump and that the pump is clear. Compare the flow directly out of the pump to what comes overboard to see if there is a blockage. After that you can look into cleaning the condenser, muriatic acid will work but there are more gentle products with a neutraliser for post treatment.
     
  4. philSweet
    Joined: May 2008
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    philSweet Senior Member

    without some more numbers, it is very difficult to pin down the cause of a flaky shutdown or say if the installation is going to cause trouble.

    AISI, in rough order of priority,

    1. Make sure the compressor is getting the very best power possible. Any undervoltage creates more heat loss. On a constant power basis, the waste heat will go up with the square of the voltage drop.

    2. Condenser cooling. like Mech says, there are better ways. But what ever you do be careful and allot plenty of time.

    3. Increase ventilation in the mech space with crossflow over the compressor towards the gen.

    4. Do insulate the cold pipe. Do not insulate the hot pipe. Carry a set of compressor repair wires because the ends will burn off the compressor if you are frequently shutting down on thermal overload.

    All in all they are pretty stout units and since you seem to have a pretty good handle on what is going on, I doubt you have much of a problem. It will probably annoy you to death before it actually gets damaged if it goes that far. Check the compressor amp draw (and voltage) when it's been running (on gen power)for a while (like an hour) and compare to the RLA on the nameplate. It should be pretty much dead on. Do this at 90 or so ambient. You may need to run a bit less refrigerant to keep the comp happy. You might look into tweaking the gen voltage as well.
     
  5. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    I have many boats that I service or consult on, every one is calling to tell me they are hot, and that there ACs are not working properly. They may have not notice that it is 10-15 degrees warmer than usual. Shade your boat with a tarp, clean your thru-hulls, add ice to your falling ice boxes, increase ventilation, be wary of duty cycle on equipment. Check your cabling for corrosion that could be causing voltage drops. Consider watering your decks to cool them down a couple times a day, take cool showers several times a day. Bunch of stuff you can do short of replacing everything, the heat will only last a couple of months.
     
  6. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    A lot of heat comes in by way of the windows, especially the inward leaning front windows of which I have 3 very large ones. Very nice in winter.

    I went out this am and ran the AC for about an hour. Feeling the exiting water it does feel warm. This is bad?
    I pulled line off of condenser and put into a 5 gallon bucket. The pump fills the bucket in 50 seconds.

    I will clean the heat exchanger with muriatic acid.
    I was reading that 5% solution circulating over and over works. But how to easily do that? The pump is a centrifugal below the waterline attched to the thruhull.
    Instead what about a funnel attached to hose ends held up and pour in 10% acid till comes out the other pipe then let it sit, flush repeat etc...

    And I will cover the suction tube with pipe insulation. I am thinking of using the foam insulation you buy at HD. It has a sticky side so it stays closed over the tube. then perhaps tape?

    Condensing unit is a type f cruiseair and will work up to 140 degrees ambient air.
    http://www.boatelectric.com/L-0200-F.pdf

    which sounds like it could get very warm to the touch and be ok.
     
  7. MechaNik
    Joined: Jan 2011
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    MechaNik Senior Member

    Did you pull the line off the entry to the condenser or the exit from the condenser? This is a comparison worth making to see the restriction in the heat exchanger.
    Is it fouled or is it blocked, sometimes a good high pressure backflush can remove silt, sediment and dead growth.
     
  8. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    pulled off before condenser.
    I can also check after but will need another hose as the hull fitting is hard to reach.
     

  9. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    I did a lot of work improving the install on the cruisair in the boat.
    I cleaned the condenser with muriatic acid. Just used funnels and poured in a 15% solution for 5 minutes. then flushed with fresh water. Looking in the pipe end looks clean. Checked pump with condenser hooked up and still flows at least 5 gallons per minute. There is very little head here perhaps 18 inches. Pump is a 12 V dc centrifugal bait well pump 750 gph and extremely quiet.

    I double insulated the suction lines everywhere. Two layers of pipe insulation.
    I plan to insulate the discharge line in the lazarette. Most everywhere it is insulated now except here and in the lower bilge.
    I made an insulating barrier of polyisocyanurate foil faced foam 2 inches thick between gen and cruisair.
    I added a sight glass.
    PSI low 70 PSI high 220 with seawater about 80

    So far it cools very well. the water discharge line is not noticeably warm.
    without insulation sheet.
    [​IMG]

    With insulation sheet. I can feel heat on gen side and cool on the other.
    I need to put some wood channel on each side to keep it in place.
    [​IMG]

    cruisair with doubled pipe insulation. I used 3/4 hose snugged up on the thicker part of the condenser.
    I do have the electric cover. I tore this apart and repaired the rust everywhere. I flipped it upside down and removed bottom galvanized plate. Removed compressor support plate and made new one from 1/8 aluminum sheet.
    Cleaned rusty compressor bottom and coated with strips of fiberglass tape and PL premium. That works great to seal out any water and stop rust. Also coated the tubing and bottom plate with PL smeared on a thin coat then white paint.

    The bottom of electric box was eaten with rust in one corner, so reinforced with fiberglass tape and PL. All nice and rust free now and sealed so rust wont form again. Regular paint wont stop rust.
    [​IMG]

    The cheap Attwood bait well pump. Very quiet running DC pump
    [​IMG]
    Relay box takes the 120V ac and flips on the 12 V DC for sea water pump
    [​IMG]

    cleaned corrosion off lower bilge copper lines. Wrapped fiberglass drywall tape then a coat of PL Premium polyurethane to seal
    [​IMG]

    with sealer on tubing. It will no longer get salt water splashing up. Tubing was from original 1971 install. I was concerned with any further corrosion affecting tube integrity.
    [​IMG]

    Lower cabin cooler unit
    [​IMG]

    Cabin view of lower cooler which has a very quiet fan.
    [​IMG]

    3 knob control with blower fan. When you slow the fan down I can hear the motor has a tiny noise perhaps worn thrust bushing. This fan blows a lot of air and on high is louder than I like.
    [​IMG]
     
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