Air conditioning install tips

Toolate

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Thinking of putting in a Dometic 10k Btu reverse cycle a/c unit and have never installed one.

The biggest concern I have is about how loud it might be running the unit and cooling pump and where I should then locate it so I can sleep when I am done drinking I mean fishing.

Thinking currently is that it will go under the helm seat which is the forward end of my galley on the S side of the boat. I have to build all of this so making it fit shouldnt be a problem but I will need to allow room for the ducts, a return, the removal of the entire unit and just general access for cleaning and service.

Any tips for me? I would appreciate even the dumbest ideas anyone has since I am starting from scratch on this one.
 

Toolate

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Here is what the boat looked like before I ripped out most of what you see. This is another forum members boat now (I copied the pic from YW because it looked nice)

image.jpg
 

osprey47

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If you are running off a genset then all you have to deal with is air noise, you won't hear the pump. The pump typically should be below the waterline to preserve head pressure -- true of Marche pumps. The compressor will not be a source of noise but the fan will but as I said before most of that is in the form of air noise. Use a dedicated thru-hull for your raw water source, again to preserve head pressure since most of the pumps are not designed to run dry.

The trade-off between noise and cool -- cool wins every time.
 

osprey47

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Assume you have sized the AC to the space you are trying to cool and if its the main cabin have a way of keeping out solar radiation. One bit of advice I was given when installing a Webasto 12kBTU unit was don't oversize the unit. It needs to work.
 

Badlatitude

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10K sounds a tad on the small side. Are you planning on only using it at night while sleeping?


ETA. Boats are like green houses. They take way more BTU to cool them down then one might think.
 
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petrel

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What are you going to use to power the A/C? You mentioned noise, so are you just going to use it a the dock w/shore power? Just curious.
 

CEShawn

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To me AC's are white noise, especially from all the other things going on around you...

What kills me is when I used to sleep with the AC off... Hearing my 3 rule electronic bilge pumps cycling every 2 minutes at different times... Ha!
 

Toolate

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Just shore power and only for sleeping. Mostly because the dock area in Block is so noisy at night and with the Oar right there....this thing might be used 4 nights a year and its usually just fine on the water.

I agree its a little undersized but again only at night and shore power since I have no genny. The sisu is actually a pretty small boat inside too.

Good advice on the pump/seacock. Any reason it couldnt share the raw water washdown seacock. I think the odds of using both are almost non existent.

Any specific pump I should choose that is quieter?
 

Badlatitude

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Since it will see little use why not look at one of thoose free standing portable units. They need a drain and vent. but they are cheap.
 
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Eslang

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Just shore power and only for sleeping. Mostly because the dock area in Block is so noisy at night and with the Oar right there....this thing might be used 4 nights a year and its usually just fine on the water.

I agree its a little undersized but again only at night and shore power since I have no genny. The sisu is actually a pretty small boat inside too.

Good advice on the pump/seacock. Any reason it couldnt share the raw water washdown seacock. I think the odds of using both are almost non existent.

Any specific pump I should choose that is quieter?

Hey,
I'm one of those drunk guys at the Oar making all that noise
Lol
 

Toolate

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Since it will see little use why not look at one of thoose free standing portable units. They need a drain and vent. but they are cheap.

Boat is pretty tight with 4 people on it. Like a household type with the duct that goes out the window? The only one of those I ever saw was about 3' tall and 16" square which is just too big to work around even for a couple days. Boat is full of crap for those trips.
 

djmarchand

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I helped my buddy do the electrical and ductwork installation on a sailboat A/C. The yard did the mechanical.

The March pump has a better reputation than the Cal. Install it below the waterline with a dedicated thruhull and of course a strainer. The raw water outlet should discharge a few inches above the waterline.

The condenser drain should preferably go to a shower sump with its dedicated bilge pump. You can dump it to the bilge if you have to. Someone makes a little ejector that lets the raw water flow suck up the condenser water and pump it overboard if you don't want to hear bilge pumps running periodically.

A 10K BTU unit will probably draw 12 amps at 120V. Use a dedicated circuit with a 15 amp breaker and wire it with 14 gauge wire.

David
 

Andyf32

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I had a March pump on my last boat and have a Cal pump on this one. The noise level is similar between them. I hear the march pumps are better but I have not had an issue with either.

Although it is not the pump you will hear but the compressor and fan. And yes they are rather noisy. That being said I find it helps to mask the outside noise. One thing to keep in mind is that some controllers will let you put the fan in an "always on" mode versus cycling with the compressor. The cycling can be more of a disturbance than just being on all the time.

I have installed a Mermaid system myself and would be happy to share my limited knowledge.
 

gmac

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Mine has unit under helm seat, the pump is in engine bay, it also has its own seacock.

You can see in the picture, under table to the left is the return vent, then its ducked to "box" beside the door to cuddy. It has a vent to lower cabin and main cabin. Unit works great, I'm not sure on size. Have a 4.5KW Northenlights gen that run it with, everything is very well sound insulated and don't find it bad for sleeping. If you are steeping on table bed, its more noticeable but others have not complained to bad!

3E63L83M55I35K75Jbd2945b2220dc25a1634_zpsedbe0955.jpg
 

Toolate

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Gmac- I would love it if you would post up a million pics of that boat in the 30' sisu boat pics thread. It is gorgeous from every angle. How much duct do you have between the unit and return grille?

Would love to see your bilge and head.

Thanks everyone for the info. Good tips.
 

gmac

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I will get some pictures of the unit in the next few days and see what size it is. When boat was in FL it kept it very comfortable.

I'll get on the pics to...
 

chortle

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I have installed a couple of reverse cycle units and the most annoying noise they made was from the solenoid valve when the compressor clicked on or off. The fan noise was, like mentioned before, more of a white noise generator. I would factor that into your location as well as putting it where you can minimize whatever duct work you have to do. As you may already know, the return vent should be in a location where it is not pulling air from the cool air discharge ducts. In both of my installs I was able to put the units in a hanging locker in the middle of the living space. It worked really well both times. The air discharge went forward through one bulkhead and aft through the other so the big bulky vent hoses stayed inside the hanging locker and I did not have to route them through multiple bulkheads and use up valuable space. How about that locker on the port side next to the companionway? Shoot some air through the after panel in the cabinet and shoot some air forward though the bulkhead, no duct work all over the place and the noise is away from the vee berth.
 
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