cruiseair question

[salty]

i have a 2 cruiseair 16k split system units.
1 services the salon, 1 services the fwd and aft cabin. i replaced the salon compressor last year. the blower units are mounted behind the evaporator coils, meaning they blow air thru the coils instead of pulling air thru the coils. this is a problem in the salon because there is not much air flow with this setup. question 1: has anyone reworked a setup like this to get the blower to pull the air thru the coils?
as i said they are both 16k units, when the compressor kicks in on both it pulls close to 30 amps. the shoreline feed for the a/c is on a 30 amp breaker with a 30 amp slow blow fuse inline. whenever i try to run both units from shoreline (50 amp service) the slow blow will pop. not right away, sometimes not for hours, and once not at all. an electrician explination was "most marina's power supplies are substandard. as demand increases, the shore voltage will drop. as the shore voltage drops the devise in the boat will end up drawing more amps than rated." this makes sense based on my symptoms.
question 2: how is it i see other boats running 3 and 4 a/c units at a time. they can't all be running 220 units can they?

38 aft hatteras

[jim rosenthal]

Most units I have ever seen pull air from the cabin and then blow it through the cold refrigerant coil. I don't think I've ever seen a marine AC that PULLS air through the refrigerant coil and then circulates it.
I think yachts with 3or more AC units alway run them on 220vac. I don't see how you could get enough amps on board otherwise. I have two 110vac units, a 16K and a 5K, and even they draw enough on startup to get the voltage to really sag. My genset runs them far better than shore power does.
Better performing AC is one of the best reasons to rewire a boat for 220vac. That is expensive and time-consuming, though. Another alternative is to replace the old CruiseAire 110vac units with modern units with more efficient compressor and digital controls. The digital controls can be set up with staggered start times so that both compressors do not come on together. This helps, as the start current is typically several times the run current. I also think the old motoryacht setup where one compressor cools two stateroom evaporators is inherently inefficient; it requires that you run refrigerant all over the boat, and it deprives you of independent control of the temperature in the two staterooms. I think you would be far better off with two smaller independent units. You could also use self-contained units and run seawater up to them as well; they operate very efficiently because the evaporator is next to the compressor and you don't have cooling loss in the refrigerant lines. Finally, I have had great success with the digital controls by Marine Air Systems. I recommend them highly.

[PascalG]

both of the cruiseair air handlers I have/had in the salon of my 70 53MY pulled air thru the evaporator, thru the blower and out. in the staterooms, it's the other way around. the blower pushes air thru the evap. and out.

which one is more efficient? i have no idea. I know that if your air handlers are low, you want the air ducted up and coming out near the ceiling. it makes a big difference in efficiency. See this page for a a few picture and description

www.pam-trading.com/pg/ga...Vthread=12 (http://www.pam-trading.com/pg/gallery/main.php?Vfnum=001&Vthread=12)

I have 4 16k btus units on my boat, 120v, and that's fine. at a time, there was a fith unit for the galley but i do not know why it was removed or when. holes where patched but can be seen... there was an extra shelf in the engine room for that 5th condenser.

3 of them are on one side of the 250v/50amp power supply with the pump, the 4th one is on the other side with the rest of the other loads. The only time I've tripped the dockside breaker is when I had all A/Cs running along with the washer AND the dryer ... I was pushing it. :-)

if someone needs to redo the complete A/C system and replace all of the condensing/air handlers then it's probably worth swithching to 250v.. otherwise.. forget it...

pascal
Miami, FL
1970 53MY

[FreestyleBruce]

I had the same problem with my two older units. They lose efficiency with age and pull more than 30amp when the compressors kick in. To get a little more life out of them, I rewired one to pull from the ship's power line. This works great unless my inverter is re-charging in which case it gobbles up all of the electricity. Other than that I don't have to wake up and shift units anymore.

[wshelton]

I have the exact same cruiseair ac unit set-ups you decribe and had two 30 amp shore power cords coming into the boat. One 30 amp was for the the ac only and other for the house. I'm not clear what your set-up is, however if like mine this is how I solved this problem. I by-passed these in-line fuses and wired in marine circuit breakers. One 30 amp for the house and a 50 amp for the ac. I installed them in a cabinet inside the aft deak of my boat which was on the other side of the aluminum box that contains the boat plugs and in-line fuses which is located on the outside. Additionally I changed out the ac shore power plug on the boat to a 50 amp 125 volt pug in lieu of the old 30 amp plug. The shore power cord had to be changed as well to a 50 amp 125 volt set-up. You may need to get creative with the male plug on this cord depending on what your set-up is at the pole on the dock. You may nned a 30 amp plug as I did which will work fine. These other 50 amp plugs have larger terminals that can handle this amperage far better than the 30 amp plugs can. Also the wire in the shore power cord is a larger gauge. This will work assuming your wiring in your boat is like mine. The wire gauge used by Hatteras inside the boat is even a larger gauge to the inlet (aluminum box) to accept this 50 amp set-up, thus going to 50 amp on the ac side was not a problem. Also, since you do not have 50 amps coming to the boat this is not a problem anyway. My boat is a 80 mod 43DC. The old shore power cord was always very warm to the touch at the connections on the old set-up, however not now. This set-up greatly reduces the friction with the larger gauge wire and plugs. Hope this helps.

[salty]

pertaining to the a/c line, along with swapping the inline fuse for a 50a inline breaker wouldn't you have swapped the 30a inlet plug for a 50a inlet. also what did you do at the a/c main panel? i seem to remember the breakers being 30a.

thanks,
jim

[wshelton]

To salty. Yes, I changed out the old 30 amp inlet on the boat at the ac side with a 50 amp 125 volt. I did nothing with the ac panel in the boat which are 30 amp breakers. I only have 30 amp coming into the boat from the pole. I wanted heavy gauge wire with the new cord and larger terminels at the plugs to handle near 30 amps continously which these units draw in the summer. I also wanted the benifit of breakers and not these out dated fuses if something blew.

[67hat34c]

i would recommend you hire an electrician for this job. have the electrician put a meter on the ac line and see how many amps it is using at run and in start up. you may find that it is drawing way too many amps due to compressor being old and warn out. a 16btu should draw about 14amps in running position.

also have him test you entire electrical system.
electrical problems are the number one cause of onboard fires.

[salty]

jim:
the salon compressor is a brand new unit (last year) and the stateroom compressor seems to be working fine so the idea of replacing either is not really appealing at this time. i had a self contained unit on my last boat and i prefer the split systems. i think they are much quieter, it also stops my kids arguing who gets to control the temp in the v-bunk.:lol

[salty]

wshelton:
wouldn't you then have 50a rating all the way to the a/c panel and then be limited by a 30a breaker anyway? and with that the same problem with the breaker tripping?

67hat34c:
i have put a meter on it and with both compressors running, it pulls 28 - 29 amps. which is where i would expect it to be. haven't tested with either of them starting up but thats what the slow-blow inline fuse is supposed to handle. i guess what puzzles me is the breakers never trip, only the slow-blow fuse. (possibly lazy breakers, they are old) the other thing is as jim mentioned my gen handles both without any problems. but i think the gen runs thru a 50a breaker to the a/c.

[jim rosenthal]

...I'm not impressed with the electrical supply to the dock posts in most marinas. Especially in the summer, when everyone is running their AC. I did live in one marina (Piney Narrows Yacht Haven) where the AC units seemed to work better...I finally figured out that it was because all of the large yachts at Piney were under cover (they have huge covered slip sheds) so the demands on the AC units were less. Their wiring is good, too. But my NL genset runs everything much better, frankly. It hardly notices when both AC units are on, and it's only 6Kva.

[rtrafford]

another trick i learned at one particular marina was that since most boats around me were running their systems off the 30 amp sourcing on the docks, the 50 amp source was rather a virgin. i pulled out a 50 amp pigtail splitter and ran my 30 amp off the 50 amp side of the console. my voltage increased significantly, and my shore cord remained cold to the touch, quite a feat as i was pulling 25+ amps continuously.

yes, the older the systems the less efficient they run. also, if your heat exchanger coils haven't been cleaned the system will run a bit "hot" on power, too.

biggest improvement i found, though, was in my power source. as you stated, things generally improve when on your own power (genset).

[wshelton]

To Salty. My problem was related to alot of friction(heat) at the shore power connections to the boat. This heat build up would constantly blow these fuses because that is what they are designed to do. By adding the heavier 50 amp plugs at the boat and heavier gauge shore power cord helped disperse the heat build up that enabled me to run both units 24/7. I was not concerned about the 30 amp breakers on the panel because I only have 30 amps coming to the boat. By adding the breakers might not have been necessary--I did it because I was so far into the project and those in line fuses offer more problems for friction too. When I get to the boat I start up one unit and let it run for a few minutes before turning on the other unit so there is no huge surge. From that point on I have encountered no problems. When you next run your systems feel the shore power cord at the boat's connections. If they are warm you got my problem. Next,If you can feel the wires inside the boat ledding to the shore power box, I'll beat you those will be at abient temp. FYI, my power plant would always run the systems --it is 50 amps.

[jim rosenthal]

..of using a 50A cordset for just the AC line.
Especially if, as you say, you only pull thirty amps max through it- you get the benefit of the heavier hardware without any of the risk of a higher amperage circuit.
I've lost my private-dock slip which I had for five or six years- the owners have decided to buy a bigger boat and need the space where my boat is, worse yet they are buying a C&C 41 or something like that- a sailboat. Bad to get kicked out, worse yet in favor of something that goes seven knots max no matter what....anyway, when I look for new dockage, I am going to see if I can find a place that's got 50A dockside connections.
Suppose I were to wire a 50A receptacle in parallel to the 30A set- I could do that, couldn't I, as long as I only used one or the other and not both at the same time? This would allow me to still run the AC when I am at a marina which does not have 50A hookups. Any advice appreciated.