Help AC Install Question
 

I am installing a 5000 btu AC unit im my 2001 sonic 31 SS. My question is has anyone ever used the hose from the outdrive that sends water to the raw water pump? Does that hose have water in it at all times or does the raw water pump pull it up to the motor? The reason being is that I do NOT want to put a hole in the bottom of the boat if I can help it? Any thought on the matter would be apreciated.

Michael

I'm no expert, but it seems to me that the suction created by the raw water pump on the engine wouldn't allow much or any water into the AC system. This means it probably wouldn't ever work while the engine was running.

I know that the water pumps on the AC units are typically not very big and usually not self priming also. They rely on being below the water line in order to function. This may also present a problem if you're trying to use the outdrives water supply. Even though it is below the waterline on the outside of the boat, it can't possibly remain so all the way into the engine room.

We have a Mermaid system on our 32SS with a brass thru-hull and a ball valve. Seems to work fine. I hate extra holes in the boat too, but that's the price you pay for more gadgets and amenities. :D

Do you have a sea strainer? many boaters use that as the water source for the pumps ont he A/C systems.
JohnnyG is right that the pumps do need to be below the water line as they are not self priming.
The boats that have systems that work when on plane have their own sepperate thru-hull pickup for the a/c system.
As long as your not planning to try and use the A/C when running i think you would be able to use the main water line from the drive.....just make sure theres no sea-weed blocking the intakes of the drive

I do not have a generator so no problem not using the air underway. But when I look at the hose from the drive to the pump it looks like it comes out of the top of the bell housing which I do not think is below the water line. Guess it is off the lift on tuesday on the trailer and chop chop with the hole saw. Thanks for the advice and let me know if you have any other ideas please.

Michael

True, but not neccessarily. I run my AC with the boat on the lift. Just gotta be creative.

i would be concerned that using the engine water you might cause the engine to not get enough water or cause the engine water pump to suck air by backfeeding thru the AC cooling system.

I thought about it sucking air from the ac unit while runing but figured a ball valve on the ac hose would solve that.

Install in a buddies Nordic they put the intake hole for the A/C on the transom down near the drain plugs. These are nice and deep in the water when at the dock, but out of the way and create no extra drag when underway.

Oh i think ive head them all by now seeing as i get about 5 calls a week from boaters asking questions about their pumps! :D

Yes there are ways of getting creative and getting them to work......theres more then a few guys ive spoken to that have cruisers that have put a "T" on the out put line to use as a fill line to prime the pump up.....theres even a few that have installed one way valves to keep from loosing the prime of the pumps....
One thing you have to remember and take into consideration on your setup when running on the lift US1.....when the pump is working and is above the water source you loose output capacity due to the fact its lifting the water...so its working first to lift, and then to try and pump....we have formulas to figure out what kind of output you would get but it drops off quite a bit the higher you get.
Now if you have agrden hose connection in the system for running on the lift.....then only thing you have to worry about is city water pressure.....The March pumps are only good to about 50psi on internal pressure.....city water pressure can be anywhere from 30psi as high as 65psi....hopefulyl you have a psi regulater on the inlet line to limit it..if not youll probably get leakage around the O-ring seal sooner or later....besides that, our little pumps "just about" never go bad. Ive got more then a few calls from boaters that have pumps go out on them after 15+ years and are looking for replacement parts!!! :D About the only thing you cant replace on our pumps is the motor as they are sealed in epoxy.

The AC water pumps have a hard plastic impeller and are magnetically coupled. If you T before the water pump, I would think the engines water pump would easily suck air backwards through the AC line. A one way or shutoff valve might work, but I expect the engine water pump would collapse the small hose to the AC pump. The hose probably wouldn't last long then.
Why not do it right? Go ahead a drill a hole in the bottom of your boat. I would prefer to drill through a non-cored hull than a wood cored transom for obvious reasons.
BTW, if you're only going to use it resting at the dock, a round "hole" thru hull at the bow will work as long as he pump is below the water line.
You'll need a scoop type pickup near the transom if you're going to get a gen and use while running.
Gary

Wally,

I have a 3-4' hose that drops down into the lake that connects to an inlet thru hull. I made a couple thru hulls that were also threaded internally from the outside to accept a theaded fitting. I just prime the system with a garden hose held tight against the inlet hose until I get water out the outlet. A checkvalve on the end of the pickup hose prevents it from draining back when the AC cycles off. I still get good flow out the outlet, plus it works great, so I guess I have no issues. I also drop a hose from the discharge fitting into the lake, otherwise the 3' water drop is noisy. I use the Mermaid Condensator which itself reduces the water flow over a normal install system. If not for that, I wouldn't need the checkvalve as both hoses are below water level and would be air free once primed. Your March pump works great for my setup. My slip neighbor uses the smaller capacity Teel pump for on the lift use also, other than no Condensator usage and 1/2 the hose runs, and his also works fine. We knew there was a possibilty of issues, but had none. Your charts only addressed 'lift' heights, not suction heights, (understandably so) so we held the pump held 5 ' over a bucket of water using 20' of hose for accuracy and see if it would pull once primed. It did, we installed. :)

Ok I did the deed and drilled a 1 inch hole in the bottom of my Sonic. All looks ok but I did use about half a tube of 5200 to make sure it wont leak.

With each new hole, it never gets mentally easier to drill them. I like the transom hole idea, no drag and you don't have to worry about trailer bunks or lift bunks.... I've seen a couple dig into the bunks already.

US1....we dont bother with suction lift as it would cause more problems then its worth for our pumps....we get enough daily calls form people that plumb the inlet side too small and starve the pumps causing damage!!! You probably have the LC-3CP-MD (our most common for marine AC systems) The next size up in family would be our series 4 pumps...and with our priming chamber installed you can actually get about 10' of suction lift possible out of the pump.....it would be slightly less out of the 3 series pumps as they have some strong shaded pole motors in them (i should know...i re-designed it! :D )
I think ive seen you post those pics before....neat idea....i take it you threaded the inlet fitting to fit that barb adapter? You know if you were at a marina that didnt have a hose/water available for priming you could buy one of those outboard priming bulbs and just stick it on the end of the hose in the water and give it a few squeezes to prime the system up....just another idea for ya ;)

East Coast B - We did it with the boat on the lift and our lift bunks and trailer bunks both sit in the same place on the boat!! So shouldn't be a problem. I said the same thing to my husband and he said transom had thicker fiberglass!! Also take a look at the AC Thread under Sonic, I posted some info on our install for you.

Yes on the thru hull fitting. Made them from scratch so I could have thicker wall. Just tapping a store bought thru hull leaves very little wall thickness for my comfort.

LC-3CP :)

Can a priming chamber work on my pump, or is it part of the 4 series? I like that idea! Is that on the March website? My only worry is my checkvalve will not seal some time and I'll loose the prime and toast the pump. Have a strainer on the hose end for added protection, plus hose is long enough to go at least a foot below water surface to prevent any surface crap from being sucked in. Using a high quality SS checkvalve for a more failure free item.

You could use the priming chamber if you wanted to....you would need to get an adapter as the chamber is made fora 1" FPT inlet size and the LC-3 has a 3/4" FPT inlet....quick trip to home depot and you could be in business.....the only other issue you would run into would be the support of the priming chamber...when you get it addapted tot he pump the chamber would be about 1/2"-3/4" off the ground so you would need to get some starboard or wood if you want just to put under it so it doesnt put undo stress on the pump inlet.....let me know if you want to try it out.... :)

I've looked on the March website, but see no priming chamber. You have a link to it in case I'm looking in the wrong area? Trying to get an idea on how it works and if it will fit. I am interested in one if it will allow me to eliminate the checkvalve, not have to prime it, and space alotment.
Thanks

Go here:
http://www.marchpump.com/documents/pdf.htm

bottom right hand corner...click on the link and it will take you to the parts sheet with pic attached to one of our 5.5 series pumps....and a dimensional drawing showing the sizing of it :)

Any idea on the $$ on this? Looks very simple and easy enough. My only concern is if it would siphon back down after the AC unit shuts off. Appears to be a trial and error testing to see if it will work under different applications.

List price is $63 but our distributors usualy sell them for cheaper.
Even if it siphoned out most of the water in the system....it would only get as far as the priming chamber...once the outlet side of the pump was suckign air it would just bubble up through the camber...and maybe empty out the inlet line....there "should" always be enough liquid in the chamber to draw fluid the next time you use the system...unless you go thrashing and empty more fluid out. :)

Oh boy!!....i think i just had the single most insteresting conversation with a boater ever! I just got a call about one of our pumps from a guy thats installing a Trane 3 ton HOME AC system on his boat!!!!!!! :eek:
From the sound of it he's gonna be spending more on retrofitting this into the boat then it would cost him to just buy a proper system!!!