A/C intake manifold

This past weekend elevated my Air Conditioning install to a higher priority. I've figured out where to locate the two units I bought, the wiring is done and I have two discharge through-hulls already plumbed up.

The problem is the water intake. I've got a spare heavy bronze through-hull with a 90 degree 1-1/2" barb connection on it. I'd rather not try to unscrew the 30-plus-year-old fitting out from the through-hull while the boat is in the water, for obvious reasons. But I've verified that the valve opens and closes well.

What I need is some sort of manifold or "Y" connector to get from the through-hull to the two 5/8" barb fittings, one on each of the two sea strainers, which will feed the two sea water pumps (also 5/8").

I found a nylon 1-1/2" barb "T", but not a 1-1/2" to 5/8" barb reducer.

Any ideas?

How far apart are the units going to be installed? On my boat, the water flows to one A/C unit, and then flows through the 2nd unit before going over the side.

Tom, why are you reluctant to unscrew the 1-1/2 hose barb?

Do you have a flanged seacock or are you dealing with a ball valve screwed onto a thru-hull fitting?

If you have to use the 1-1/2 hose barb, you can use a short length of 1-1/2" hose to conect to an 1-1/2 hose barb screwed into an 1-1/2" pipe tee. Put bushings into the other two outlets on the tee to reduce them to 1/2" female pipe thread. Both Groco and Perko make 1/2" mpt X 5/8" hose barb bronze fittings.

What I've described is a really ugly way to do it.

You really need to get that 1-1/2" 90 deg hose barb out to do it right.

Here's a picture of what I'm dealing with:


I guess my fear is the unknown, will the threads stick, will I end up turning off the top of the through-hull, instead? Will something break or give way? I don't want to end up with an emergency haul-out because of this project.

None of the boat stores near me have a very large selection of fittings, and their on-line catalogs don't seem to list many parts. I'll look up the Groco and Perko part numbers and maybe they can order them. I'd hoped to have A/C within a week, but it looks like this is turning into a long-term project.

Go to the box store and purchase a hose to pipe barb and a brass T fitting.

Bronze is better but hard to locate.

Short piece of 1 1/2 hose to the T.2 marine hose clamps each end.

Use bushings to mount 2 valves , SS ball OK, and then adapt from the valve to the AC supply hose.

About a half hour after you get the parts, your done.

Bronze T might eventually come from a better marine supplier.

The T might want to be on a longer hose (to above the WL) as you will at times need to remove it and ram the hose/thru hull with a hunk of old garden hose to clear debris or jellyfish.

Is there a raw water pump for each unit? I have two A/C units but a single high capacity pump and strainer to feed both units.

Bob

Thanks FF, I'm going to try to hunt down some of those parts. You're right that fitting them all together will be the easy part. Figuring out what to get and where to get them is the challenge.

Bob, I already have the two 500GPH pumps, so I'm going with the redundancy theory at this point. Your set-up is probably safer in the end because there are fewer fittings, hose clamps, adapters, etc. below the waterline.

A/C pumps like to live below the waterline since they're not self-priming. I was planning to put a manual vent somewhere higher up so that if the pumps do get air-bound, it's just a matter of opening a valve and they'll fill to the water line. That little feature saved me many hours of frustration on my last boat.

The hunt was successful. First I tried Lowe's. Nothing over 1" in brass, and even then slim pickings. Next was the plumbing supply store. Only took a few seconds to explain what I was trying to do, and the guy came back to the counter with the 1-1/2" tee, two bushings and the 1-1/2" NPT to barb adapter. He didn't have the 5/8" barb adapters.

Next to WM. I found the two adapters and picked up some hose.

That part's done. Now to find a nice, neat way to pack all this out of the way in my engine room.

Now to find a nice, neat way to pack all this out of the way in my engine room.

Not so out of the way that clearing it , with out accessing the sea cock ay 0 dark 30 , will be too big a hassle.

Good point. I probably spent an hour last night just looking, measuring, sketching, and scheming. I also put a big pipe wrench to the through-hull tailpiece just for fun. Couldn't even budge it. I decided against going back and trying again with a cheater bar. No telling what might give first.

So, my plan now is to mount the pumps and strainers on a board that will fit snugly in a little outboard corner of the engine room where an obsolete shower drain pump now sits. I should be able to clear the strainers relatively comfortably by laying across the battery box cover. From that same position I can easily manipulate the seacock on the through-hull.

Both shower drain pumps (fore and aft) are being replaced by new shower sumps, to be located in the bilges amidships somewhere between the showers and the new A/C units, so they can take both the shower water and the A/C condensate.

With those two big 500gph pumps I would be concerned that if one pump is off, the other one would pull the water out of the other unit and suck air through the discharge line. I guess it really depends on how free the intake flow is.

Bob

I see your point. I'll leave room for check valves.

I see your point. I'll leave room for check valves.

Might be simpler to simply throttle the pump with the installed ball valve.

Figure a way to lock the handle in place , or better use a different style valve with finer adjustment that doesn't shake to a different position.

Sounds like a good place for a circuit setter balance valve. Set desired flow then snug down the set screw so the setting will not easily change.

CaptTom said:

I guess my fear is the unknown, will the threads stick, will I end up turning off the top of the through-hull, instead? Will something break or give way?

Click to expand...

This thread is starting to get really silly now with proportioning valves, multiple pumps, throttling seacocks and who knows what next.

Use one large pipe wrench or a proper sized wrench on the flats to hold the seacock and another pipe wrench to turn the barb fitting. Use a length of pipe stuck inside the barb to gain leverage and if that doesn't work easily, use a propane torch to heat the barb then try it again. It will unscrew without doing any damage.

Why 2 pumps? Is airconditioning a critical system? Why add complexity and cost?

I have two units a 16000 and the 12,000 BTU they both are cooled and work fine with 1 500 G p H pump

>>>Why 2 pumps? Is airconditioning a critical system?<<<

It sure is if you live in Texas. I just converted my two systems to run off one pump. One seacock, one strainer, one pump.

Bob

A crtical system is "the equipment or technical systems that the sudden operational failure of may result in hazardous situations."

A sweaty grumpy wife may be a relationship hazard but the loss of airconditoning does not put the vessel at risk.

CaptTom,

You did not mention the size of your A/C units, so unless you have a pair of 16,000btu systems, you could be a good candidate for a single 500gph pump system like BobH and Motion30 described.

For most current marine A/C systems, the raw water requirement is 200gph/ton at temperatures up to 100F. One ton is 12,000btu so a 500gph pump would theoretically be able to supply about 30,000btu of A/C capacity. Pump output capacity is normally measured at 1' head, so if you have any long hose runs, elbows, reducers etc., the flow will be reduced somewhat. Make sure the condensing coils in your units are clean and use a quality high capacity raw water strainer. You will need to connect the pump power leads to both systems so that either will be able to energize the pump when needed. Some systems require a relay box for this, but I think most modern controls have a dedicated power connection for pump power.

A single pump would certainly make for a cleaner installation and be easier to service.

Good luck!

RickB said:

A sweaty grumpy wife may be a relationship hazard but the loss of airconditoning does not put the vessel at risk.

Click to expand...

Depends upon that sweaty grumpy wife's ability to curtail the use of the boat, could be a risk of selling said boat. FTR I agree with everything you've said in this thread.

RickB said:

...Why 2 pumps? Is air conditioning a critical system? Why add complexity and cost?

Click to expand...

We have 2 - 16,000 BTU systems with 1 pump. After talking to AC repair guys they suggested 1 pump for simplicity. If 1, 2 or both units are on, the pump is also. We split the water to each unit after the pump.

If you are going to use the AC while under way, you should also have a sea water scoop. AC pumps are not self priming and the scoop will help keep water to the pump (s) while traveling.

>>>A sweaty grumpy wife may be a relationship hazard <<<

You haven't met this sweaty grumpy wife. Actually we only use the A/C in a marina. We only ran it a couple of times while cruising to cool the boat down in the evening at anchor and a few times in the morning to get the chill off while coming down the East Coast in October.

Bob

CPseudonym said:

Depends upon that sweaty grumpy wife's ability to curtail the use of the boat, could be a risk of selling said boat..

Click to expand...

Geez! Don't let your wives have that much power! My wife does exactly what I say and always walks a little behind me. (Is she reading this?)

SeaHorse II said:

Geez! Don't let your wives have that much power! My wife does exactly what I say and always walks a little behind me. (Is she reading this?)

Click to expand...

ROFLOL!!

You da man Walt!!!

Do me a favor and train mine for me, 26 years of trying has gotten me nowhere compared to you

My wife walks behind me as well. Does it count if she's always yelling at me to slow down?

Not all "sweaty grumpy wives" are bad.

My “sweaty grumpy wife” gets up in the middle of the night, goes up to the main cabin, lifts the port engine room hatch ( it’s got gas hyd lifts so it’s pretty easy), shuts the seacock, removes the strainer basket, and dumps the debris and jellyfish over the side.

Puts it back together and restarts the AC unit and crawls back into bed without once waking me.

I’m a lucky guy.

As an aside, did you know you can have too much water flow thru a AC condenser? I learned the hard way.

Mike

Sceptic , did you use a choker collar with spikes , or the electric unit with a remote to do the training?

Any boat or RV work , by bride sez" BLUE WORK," and its not her problem.

>>>As an aside, did you know you can have too much water flow thru a AC condenser? I learned the hard way.<<<

OK, I'll bite, tell us about it.

Bob

Sceptic said:

As an aside, did you know you can have too much water flow thru a AC condenser? I learned the hard way.

Click to expand...

Doing a $60K+ repair on a boat right now for just that reason.

I’m hoping RickB will return and correct this post, subtract from it or add to it as necessary.

During the rebuild of the little DeFever I installed a 16,000 btu Aqua Air ac. I wired it up electrically, installed the electronic controls, the seacock and strainer, ducts and return grill, and then stopped working on the ac. The boat was on the hard and would not splash for at least another year.

I put the boat on a truck to go back to SC to have the Cummins installed.

I asked the yard to complete the plumbing of the ac.

2.5 years later the Aqua Air failed. I called a repairman. His conclusion was that I had water in the refrigerant.

So I started looking for a replacement. I noticed that Mermaid published min. and max flow rates for their units. I had not seen max flow rates on any other site, so I called Mermaid tech support and was given this answer - “too much water results in turbulence and if there is any grit in the water it’s like a little sand blaster. It takes a while but you end up with little holes.”

Next I called Aqua Air and got the exact same answer.

I went down into the engine room and looked at the pump name plate for the first time - 1000 gal per hour - double the recommended upper limit by both suppliers.

Like I said, I learned the hard way.

Mike