A/C sea strainers

I have a Cruisair smx air conditioner.My boat is currently in Pensacola.When not aboard I leave the A/C in the dehumidify mode.As presently programmed this runs the unit approximately 8 hours of 24.I find the sea strainers infested with sea grass and barnacles after several weeks.What is your experience along the Gulf coast running your A/C part time?

Same thing.


David Hughes
2009 Leopard 37 Powercat
Cape Coral

I'm on dauphin island in a shallow mud bottom marina. I have to clean strainers about once a week if I haven't left the dock. We are at the mouth of mobile bay so water can be unusually silty. We set ac's at 80 and leave refrigeration on full time. Your water is certainly clearer most of the time but several weeks seems too long to go between cleanings. I did hook up a manifold that I can hook a water hose to and by changing valves can blow out each line with full dockside hose pressure. Works well to keep all hoses clear as well.

You can try using chlorine or bromide tablets in your strainer. Otherwise don't run your A/C system as it will gather what you already see. We use a dehumidifier in our galley with it draining into the sink? We also have several fans running full time in all the spaces to move air around. Does nothing for the heat but sure hold down the humidity.

I use a perforated strainer on the outside that would eliminate the grass issue. Would still need to scrape the growth off of it periodically. If you have a strainer on the inside, try a pool chlorine tablet in the strainer. Let it sit or a few minutes and then run the pump for 15 seconds, followed by no use for a couple of hours. Should kill anything growing.

Ted

We've been cleaning ours every week or two and we put a piece of a chlorine tablet in it.

Different place, but we're in a heat wave right now so the weather is likely similar...

FWIW, instead of dehumidify mode, I usually set both thermostats much higher than when we're aboard, partly to knock off higher day-time temps, partly to give the wallpaper glue and the fridges a bit of a break.

Augmented by having the blowers set to run constantly. Augmented further by a table-top fan (or sometimes two) in each area.

I've read chlorine tablets may be too corrosive, whereas bromine tabs might or might not be. I have no first-hand info. Haven't resorted to either of those, but then our more normal problem is mud and/or sea nettles (jellies).

Periodic flushing with raw water, and cleaning the strainer basket, seems to be necessary at least once and often twice/year. (Just did that this last Monday; wasn't even as bad as I semi-expected.)

I've read a small piece of copper in the strainer will work for critters like barnacles; I have a small copper elbow in our strainer, no barnacles, can't say whether that's a causal relationship or not.

Last year I flushed our system with Rydlyme, got lots of gunk out. Can't yet tell if that might become my annual service routine; might wait 'til next season and then see what comes out... if anything.. before deciding.

-Chris

Star0210 said:

We've been cleaning ours every week or two and we put a piece of a chlorine tablet in it.

Click to expand...

What are you getting in the strainer ?

kartracer said:

What are you getting in the strainer ?

Click to expand...

Mostly a slimy kind of build up.
The first time we cleaned it, it was pretty bad. Not sure how anything was getting through. There was some grass and a bit of trash.
It's not that bad now that we're doing it so often.

Just a note. If the strainers are getting fouled, regular cleaning of the heat exchangers should be part of the routine also.

Thanks all for your input.I have tried a dehumidifier but didn't like the fact that it raised cabin temps to 110 degrees.Prefer not to leave the a/c on full time,so will reprogram Cruisair smx to operate less often.Also found this article on bromide vs chlorine.Will try bromide as I am concerned about the corrosive effect of adding chemicals to the a'c system.This does make me wonder about the engine cooling circuits.
A popular substitute for chlorine is bromine (Br2). Like chlorine, bromine reacts with water to produce a hypohalous acid, in this case HOBr. Bromine has nearly the same oxidizing power as chlorine, but it offers several advantages over chlorine in certain conditions. First, the dissociation of HOBr occurs at a higher pH than HOCl (Figure 2), which makes it more effective in alkaline environments. Second, bromine does not react irreversibly with ammonia as does chlorine. Chloramines are much less effective disinfectants than free chlorine, which makes chlorination of ammoniated waters problematic. Third, bromine is less corrosive than chlorine to copper alloys.

We're docked on on the Gulf ICW just west of Pensacola at Perdido Key, and we've had a very hot summer with an extraordinary amount of sea grass washing to shore every still evening and night. We still have our Sea Ray docked next to us that has the standard clamshell bottom strainer to through hull and an oversize 1'' Groco sea strainer for AC's set at 78*. That sea strainer gets cleaned twice a week.
Now the Commander -- we were waking in the middle of the night sweating to find the AC off every night even after cleaning the sea strainer at dusk the evening before. After he dove and found the AC through hull to have No bottom strainer at all, we fashioned a pvc pipe strainer capped and drilled with small holes to keep the grass from coming through to the Groco strainer -- another 1" oversize with a big basket. It works. We can go a week now, and just clean out a little bit of grass and slimy silt.
The first picture is the amount of grass we were getting twice a day, and the second is the amount of grass washed next to our docks. This is ongoing for several weeks. it's not a one time event.

For grass, I have a buddy who uses a small bungie cord to attach a plastic colander underneath his hull over the AC inlet. It works really well, but you obviously have to remove it before travel.

Dougcole said:

For grass, I have a buddy who uses a small bungie cord to attach a plastic colander underneath his hull over the AC inlet. It works really well, but you obviously have to remove it before travel.

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Can you provide a little more detail as to how this works (i.e., is attached to the boat)? We've never had an issue with our main engine and AC intakes, as they are deep in the hull, near the keel, but we've had numerous issues with our generator clogging, as the intake is located closer to the waterline. I've been trying to come up with ideas, as we have a lot of hydrilla and sea grass this time of year. Last year, we had the genny clog, overheat and shut down three times in one weekend. Unfortunately, by the time it overheats and shuts down, the impeller is usually toast and also has to be replaced. If others have ideas, would love to hear them. So far, we have considered going with a larger strainer (which just means more time before it is full) and/or installing a strainer/clam shell on the outside of the hull at the intake, but that will require a haulout.

We are live aboard so boat doesn't move much. Sea grass will drift with the tides and work it's way down the hull and finds the intake. Took a 5 gallon bucket ,cut the bottom off about 6 inches up,drilled many 1/4 inch holes in it and attached it to the clam shell with a large zip tie. Still have to clean strainer,but not weekly but monthly. Of course I have to remove to cover when we move the boat, no problem as I dive to clean the props,running gear anyway.

We noticed Saturday evening after returning from a day out on the river that the AC's were barely pee'ing (because I don't know the proper terminology).
Hubby got the bottle brush thingy and cleaned out the holes where the water comes out and then cleaned the sea strainer. It was very clogged up. We were surprised at how dirty it had gotten so quickly.

Does anyone make a back flush attachment for the strainer?
I'm just wondering if there is one available then you could hook up a hose and shoot water backwards to clean out the strainer quickly. Just random thoughts....

Star, I thought 'peeing' WAS the technical term! It's what we use.

folivier said:

Does anyone make a back flush attachment for the strainer?
I'm just wondering if there is one available then you could hook up a hose and shoot water backwards to clean out the strainer quickly. Just random thoughts....

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Groco makes a "safety seacock" that comes with a flush adapter to form a conceptual T... and I'd guess garden hose pressure could flush in both directions. We've only used ours to flush in the direction of the ACs and overboard from there...

-Chris

I was thinking more of adding a tee to the outlet from the strainer. Then a valve on the end going to the a/c and a valve to the other side of the tee. When strainer gets clogged you just shut off the a/cs and pump, shut off the valve supplying water to the a/c pump, connect a water hose to the other tee and open that valve, then run water backwards through the strainer. Think that would work?
If you're in an area that frequently clogs the strainer it might be worth doing.

ranger42c said:

Groco makes a "safety seacock" that comes with a flush adapter to form a conceptual T... and I'd guess garden hose pressure could flush in both directions. We've only used ours to flush in the direction of the ACs and overboard from there...
-Chris

Click to expand...

A variation on the Groco "safety seacock" concept is to install a bronze 'T' (lengthwise) directly to the existing seacock with a short nipple. Install a removable plug in the topmost end of the 'T' directly inline with the seacock bore. Connect the strainer directly to the 'T' with another short nipple, or to hose barb and hose if farther away. Finally, install an inline ball valve on the pump side (outlet) of the strainer.

To flush, close the seacock, close the strainer outlet valve, remove the plug and replace with a hose adaptor, attach a water hose, open the seacock, turn on the water hose and blast away. Reverse when complete.

An added advantage is that by closing strainer outlet valve, you can clean the strainer basket without losing losing prime to the pump. It can even be used theoretically to circulate or inject coil cleaner using the a/c circulating pump, but that's another subject entirely.

folivier said:

I was thinking more of adding a tee to the outlet from the strainer. Then a valve on the end going to the a/c and a valve to the other side of the tee. When strainer gets clogged you just shut off the a/cs and pump, shut off the valve supplying water to the a/c pump, connect a water hose to the other tee and open that valve, then run water backwards through the strainer. Think that would work?
If you're in an area that frequently clogs the strainer it might be worth doing.

Click to expand...

Yep, you could install the Groco thing on either side of the strainer. Ours happens to be on the thru-hull side, partly because that was the easiest place to put it in our installation.

OTOH, I've not had much luck with that being the best way to clean the strainer. I've invariably had to open it up and remove the basket...

-Chris

strainer clean out

I have had good results sticking a garden hose into the strainer to unclog an obstruction in the hull inlet. I use a rubber coated nozzle at the end of the hose, unscrew the strainer lid (not much water comes out since the inlet is clogged), jamb the rubber coated nozzle into the inlet side of the strainer, then turn on the water and it seems to blast out the obstruction pretty quickly.

Obviously this only works with a clog and not barnacles or other clingy stuff.

I was in little chop tank river, slaughter creek this past week and ran my generator for 14 hours when it over heated. I found four jelly fish and a load of sea grass jammed up the strainer and inlet pipe. The strainer was easy to clean, the inlet pipe was not. They used a 3/4" street L which really restricks flow with any obstruction. I dinghy into marina to barrow a hanger to try and remove grass from 3/4" inlet pipe before the strainer. I disconnected the 3/4" hose at the generator pump and back washed the entire line. If I ever change out the through hull I would go to a 1"line. I will also check the strainers daily if I use them that often in the future.


I did add a brass tee and brass hose cap just before my A/C strainer for easier winterizing. It would have come in handy if it was on the generator inlet pipe. I guess the only problem would be if it was so clogged it pressurized the strainer itself? The plastic sea bowl would not take a lot of pressure.
Grass is a pain in the ass and the jelly fish are bad this year.

I bought one similar to this to carry on the boat.
https://www.amazon.com/Powered-Action-Plunger-Toilets-Showers/dp/B00TE9CL2I
It has several tips to fit (home) toilet, pipes, strainer, etc.

Jellyfish are a problem around here sometimes clogging strainers. We haven't had a clog yet maybe buying the set was good insurance.

I've run a bottle brush right thru the open seacock with great success.

Carolena said:

Can you provide a little more detail as to how this works (i.e., is attached to the boat)? We've never had an issue with our main engine and AC intakes, as they are deep in the hull, near the keel, but we've had numerous issues with our generator clogging, as the intake is located closer to the waterline. I've been trying to come up with ideas, as we have a lot of hydrilla and sea grass this time of year. Last year, we had the genny clog, overheat and shut down three times in one weekend. Unfortunately, by the time it overheats and shuts down, the impeller is usually toast and also has to be replaced. If others have ideas, would love to hear them. So far, we have considered going with a larger strainer (which just means more time before it is full) and/or installing a strainer/clam shell on the outside of the hull at the intake, but that will require a haulout.

Click to expand...

He has a clamshell strainer on the outside of his hull, he hooks one end of the bungie in it, then hooks the other end through a couple of the holes in the colander. The pressure of the bungie holds it tight against the hull. The surface area of the colander is enough that it doesn't plug with grass.

I had a similar problem with the inlet on my Genset at our favorite Bahamas anchorage. All through the incoming tide the genset would clog with grass every 30 minutes or so. Last haulout I installed a clam shell...one of the hinged kind from Groco, I got it from Parks. It works perfectly.