How Cold is Cold? (A/C question)

Here's what I've surmised... 32,000 BTU should be more than enough to cool my boat to more than 10-12 degrees below the outside temperature. Given that both units are drawing from the same water supply I'm going to negate that as a concern (plus water temp is 80 degrees).

Also, did I mention that the aft compressor has "iced up" on me a couple of times? Does that help with the diagnosis xravenx et al?
 
prodigalson said:
My salon A/C seems to have a tough time keeping the interior at anything more than 10-12 degrees below the outside temp. I would have expected more like 20 degrees below.

The forward unit has no trouble, but of course, there isn't all that glass up front like there is in the salon. Anyway, I measured the temperature of the air coming out of the vents and it is 51 degrees up front and 58 degrees in the salon. Seems to correlate with the cooling results, but why? The unit is under warranty and a call has been placed, but I don't think they took me very seriously since it was in the middle of a heat wave and lots of people were calling with issues. Yes, I cleaned the filter.

So, is 58 degrees acceptable, particularly considering that a same-sized unit up front is putting out 51 degrees?
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When checking a car's a/c the tech always inserts an a/c air stream thermometer into the vent, turns the a/c on max and the outflowing air should reach 40F in about five minutes or faster depending how hot the car was for him to give the system a clear bill of health. I would think your boat's a/c should accomplish this too.

We have the a/c on our 340 our a/c set at 70F to 68F mos tof the time in the hot summer weather and it gets our cabin down to 68 or even 65F without delay and then begins its on/off cycling as the cabin heats and gets cooled down again even when the ambient temps are 95F outside.
 
Four Suns said:
xravenx said:
If you can lower your inside temperature about 20 degrees less then the outside temperature, you are doing good

John
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My wife would make me get a different boat....
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I agree ... my a/c at home and on the boat is doing better than that ..
 
Robski97 said:
Is it me or do some people use way to many sentances to make a point.

Rob
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Is it that they use too many sentences to make a point or that they use complete sentences that bothers you. :smt043
 
First Born said:
Robski97 said:
Is it me or do some people use way to many sentances to make a point.

Rob
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Is it that they use too many sentences to make a point or that they use complete sentences that bothers you. :smt043
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Wesley, can we keep to the topic? :lol: :lol: :lol:
How long have I wanted to say that! :grin:
 
Sorry for the hi-jack of your post prodigalson, wish I could help on the A/C question but we have yet to be able to find one on our boat. I just felt the need to get my post count up.

Glad you were able to get me!!! :thumbsup:

Wesley
 
Robski97 said:
Is it me or do some people use way to many sentances to make a point. Ravens right on . I like my boat cold ... I set the cabin for 68... on hot days it never gets there.... and yes the cabin door is never closed ,,, thats a no brainer ... but with two young kids and a dog some battles u just dont pick. Butthe a/c unit on the 42 is only 12,000 btu's . Id have liked it bumped to a 16,000 btu unit . Same foot print. alittle more amperage ... its on the to do listfor next year...

And the cockpit a/c is joke ....


Rob
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What ??? Only a 12,000 btu unit on a 42?? You should have at least two of those since the 42 has two units, right ... heck, my 340 has a 12K but a/c unit ..
 
prodigalson said:
Here's what I've surmised... 32,000 BTU should be more than enough to cool my boat to more than 10-12 degrees below the outside temperature. Given that both units are drawing from the same water supply I'm going to negate that as a concern (plus water temp is 80 degrees).

Also, did I mention that the aft compressor has "iced up" on me a couple of times? Does that help with the diagnosis xravenx et al?
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Icing up a evaporator ... hmmm ... That would happen if the refrigerant is low on your unit and that will also significantly reduce the cooling and dehumidifying capacity of your a/c
 
Robski97 said:
Is it me or do some people use way to many sentances to make a point

Rob
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If this remark was meant for me I apologize for trying to clarify the issue for the laymen, not the experts like yourself.

Also, that would be "too" many, not "to" many. It's confusing though, so no biggie...oh, and look out for that tricky "two".
 
Alex D said:
When checking a car's a/c the tech always inserts an a/c air stream thermometer into the vent, turns the a/c on max and the outflowing air should reach 40F in about five minutes or faster depending how hot the car was for him to give the system a clear bill of health. I would think your boat's a/c should accomplish this too.
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Not so Alex, car ac units are different because the speed and capacity of the compressor varies with engine speed. 40 deg discharge temps are not common because that would require evap temps that are below 32 deg causing freez-ups. Cars have pressure/temp controls to avoid this.
 
WTf.. talk about piling on..... JG u confused the crap out of me with ur post and i somewhat know what im talking about...

Simple fact not to be lost in all the crap is 15 degree temp difference between space and air coming from the vent is acceptable.

Rob
 
It's all good Rob, just trying to explain to some others how it works and what to expect from their systems.

Joe
 
Robski97 said:
Is it me or do some people use way to many sentances to make a point. Ravens right on . I like my boat cold ... I set the cabin for 68... on hot days it never gets there.... and yes the cabin door is never closed ,,, thats a no brainer ... but with two young kids and a dog some battles u just dont pick. Butthe a/c unit on the 42 is only 12,000 btu's . Id have liked it bumped to a 16,000 btu unit . Same foot print. alittle more amperage ... its on the to do listfor next year...

And the cockpit a/c is joke ....


Rob
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I replaced my salon AC unit this past winter. The compressor failed. I bumped it up to 16,000 btu's - the upgrade was $300. Well worth it. I used to keep the setting at 69 degrees to keep the boat comfortable. The unit never turned off during the day with all the cabin door opens etc. Now we set it at 75 and it cycles on and off. My buddy says I could hang meat in the salon. I will bump up the cabin AC unit when it fails. You can never have enough AC in south Florida.
 
I have a small 240 but I was having a/c "issues" also. They, "service" relocated my thermister(spelling ?) the thing that senses the inside temps, and it works better now. :huh: Worth a try?
 
UPDATE: The Cruise Air tech was out and confirmed that the unit is operating properly. He did, however, note several major installation issues which could only be defined as design flaws.

1- The air intake area needs to be no less that 144 square inches. It is approximately 34 square inches.

2- The air outlet is also too small by a similar margin (I don't remember the exact dimensions).

3- The unit is installed so it can draw from other areas like the uninsulated hull sides. I.e., the salon is not the only area from which the unit can draw air. This issue exacerbates issue #1. The inability to draw enough air from the salon forces the unit to find it's air supply elsewhere.

So far, the dealer has asked the tech to try to find a solution. I fear their patience for this may wane as the solution becomes more, shall we say, "structural".

I will keep interested parties posted on this as things progress.
 
Keep us posted. I'd like to see how they handle this . I'm in the process of swapping out my 12,000 btu salon a/c with a 16,000 btu unit. I know on my boat I get cold air leaking out of the cabinets as I guess they used the space behind the cabinets as a supply phlenum. MAkes for nice cold storage but doesnt help cool off the boat.

Rob
 
Robski97 said:
Is it me or do some people use way to many sentances to make a point. ...

And the cockpit a/c is joke ....


Rob
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<As I remove the blade from between the ribs ....>

What BTU unit do you have in the cockpit?
 
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