420DB – Bridge A/C and Heat Installation

Greg said:
That one may work. But if I were you I would go with this one:

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Then if this whole A/C doesn't work out, at least you'll have a way to get beer up to the bridge. :)
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:lol:...that's a good one, Greg.

It's gonna work just fine, one way or the other. :thumbsup:

douglee25 said:
Sounds like you got all the details now!

Doug
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For the most part I'm good, but if I can only have more responses on Ocean Breeze reputation and their products it'll make my job on picking the unit much easier. I think that their 22K BTU unit should be the way to go, but I just want to do a little more research and do more detailed comparison to Dometic units. I've got to finish my spreadsheet, right? :grin:....only then I'll know for sure what I'm buying.
 
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Is the Oceanbreeze unit inverter driven? If so that's the unit to use. These units use D.C. compressors and motors which use much less current to start and run putting less stress on your generator system and alleviating the problem of multiple A/C units running simultaneously.

If it uses a standard compressor and components then there is very little difference between manufacturers as they will all be using the same components.
 
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I have doubts that it's an inverter driven. If they did, it sounds like a great selling point which I assume they would advertise. The other puzzling and slightly different thing is that OB 20K and 22K units have electrical heating elements (2 x 2kw). They told me that one is hocked up by default and there's a 2nd line for the other heating element. Both lines would require 17amps each. If i only need to use a single 2kw heating element, then my max is 17amps, but if I need the other one as well, then I'm in to 34amps, which is a lot.

OB told me that they can make the unit have reversed cycle heating and they do it all the time, but they said that electrical is more efficient. I thought that having reversed cycle would make things simpler.

What you think?
 
Electric resistance heat is more efficient by far and contains fewer moving parts making it far more reliable. Reverse cycle heat is limited in it's heating output as the entering water temp drops. The less heat the entering water contains the harder for the unit to extract it.
Also with electric heat there is much less run time for the compressor and that equates to longer life.
Given the choice electric heat is a no brainer.
 
That's great! This makes it another selling point for OB 22K unit.

Do you think I'll be ok with just single 2KW heating element for my bridge? I think I should be fine as I've used a small space heater from Home Depot. It's a simple standing unit with diagonal display and it's rotating. I forgot the output specs on it, but it does a fantastic job. On a 45* night we were sitting in t-shirts.
 
Another plus about the electric heat is that if the unit is on the hard or in the water, you can still run the heat in the winter without disturbing anything that's been winterized. The fan motor plus the heating element is the only thing that will be running.

Doug
 
You're right, Doug. However, they way they shrink wrap the boat the bridge is wide open and you'll have to heat up the "whole tent". In any event, I think it might be a better choice going with electrical heater.

I just looked up mine on HD site: http://www.homedepot.com/h_d1/N-5yc...=electrical+heater&storeId=10051#.UENRwlH3AfE

According to HD's specs it's a 1500W unit. So, if this little thing was doing a great job heating up the bridge, I think 2000W built-in to the OB unit element should be plenty.
 
How many things do you have to turn off to run the electric heater?
 
If you need 1500 watts, how 'bout one of these? Better yet, TWO of 'em. ;-)
hair-dryer.jpg
 
My admiral won't use it even for hair drying, it's too weak (so she says). I think her's is at least 1800W (some special italian brand), that's why she trips the GFIs once in a while.
 
My understanding is that wear to A/C systems comes from cycling, not running.

Make sure that your through hull and plumbing does not restrict an 1800gph pump.
 
I can't see how a 1" hose has enough volume to feed 3 units. Then decreasing the volume to create pressure to feed the bridge unit? Sounds like a recipe for starving ac units to me. If I remember correctly, we had this discussion in the fall with the winterizing water pump contraption being fed by a garden hose. pressure doesn't equal volume. You also have to take into consideration how much pressure your system can take. You throw on a huge pump and you may start blowing hoses all over the place.
 
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A 1" pipe will flow flow more than 1800 gph assuming pressure between 20-100 psi in a pumping situation.

Doug
 
Ok, what's the suction pressure of an 1800gph pump though a 1" hole on the bottom of his boat?
 
You will have to consult the pump curve that every manufacturer supplies with their pump to see what the NPSH (net positive suction head) is for the given conditions.

Doug
 
Correct, you also have to take into consideration the depth of the pickup, the height of the pump, the length of tubing and the bends, and the flow through of the strainer, and the fittings on the pump. Once you figure that out, then you'll know the maximum that pump can draw.

How much pressure can the system tolerate? I mean that's a ton of pressure. A hose clamp lets loose and you're in a world of hurt.
 
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