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Captain
Posts: 156
Home Port: Edgewater Maryland
IP Logged | I have three thru hulls where the raw water comes out for my AC. The mid ship combines the two units on the bridge and has a very robust stream. The forward two are for the forward and mid cabins. Those streams are somewhat weak. I have cleaned the lines and the T fittings in the forward bilge and engine room. When I run water through the forward units from the dockside hose the steams are strong indicating no obstruction. My question is...in the engine room the water goes from the pump to a T. The T is oriented with the inlet and bridge side running vertically and the two staterooms horizontally. It seems to me that the inlet water should go in the bottom of the T and then it is spit evenly to the two directions...How is yours set up, or have you changed the orientation? |
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Admiral
Posts: 708
Home Port: Wrightsville Beach, NC
IP Logged | Max - my set up is just like yours. Mike on Nautimary might be able to give you additional advice, but it sounds to me like you might have some scale build up in the A/C unit itself. A little muradic acid through the unit might clear up your weak water flow in the forward units.
I have also had luck with squirting a hose from the outboard side into the discharge lines. Sometimes you can get a shell or mussel stuck in the line and changing the direction and force of the water will sometimes dislodge it. |
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Admiral
Posts: 1207
Home Port: Vancouver, BC
IP Logged | Max - same setup as above and same observation regarding the waterflow. Have not had problems though. |
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Captain
Posts: 110
Home Port: Monmouth Beach, NJ
IP Logged | Have same setup on my 411.
Once had reduced flow from one of the outlets.
Turned off the valves leading to the other two outlets which increased flow and pressure in the one with reduced flow.
Took about 1 minutes to "wash" out the reduced flow unit and return it to normal. Opened all valves and all has been fine since. |
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Admiral
Posts: 339
Home Port: Solomons MD
IP Logged | Max, water will take the path of least resistance everytime. They piped it they way they did for a reason I think. The end going up to the bridge needs the most pressure do get it up that high. I get the most flow to the bridge and I closed the valve down a bit to help get flow to our aft cabin. Ours was piped with one line up (to the aft) and one line down (to the bow) on the horizontal manifold. I repiped with both lines on the bottom. It made very little difference and don't think it was worth it. Since the other lines go into T's before they exit the boat, this causes the stream to backwash and not come out as strong as the bridge lines. Are you having problems with a unit? You may just need to acid clean it. |
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Admiral
Posts: 723
IP Logged | I have a strong flow from all three but I don't think I have any valves on the hoses from the pump.
If you get a strong flow from a garden hose, do you have a pressure reducer onit or do you blast full pressure since that is clearly more than the pump would give I believe.
h |
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Deck Hand
Posts: 23
Home Port: Lindenhurst, NY
IP Logged | I'm puzzled as to the whole A/C situation. Last year, when my boat was new, for the first few months the water flow from the aft overboard poured out in an even steady arc. Shortly after, the flow appeared to be flat and somewhat fanning. At first, the only problem that it seemed to cause was the perpetual rust stain. I would clean it and within an hour it would gradually start coming back. Finally, the unit in my forward stateroom went into "HPF" every few days. They blew out the lines several times but, it never seemed to change the flow nor resolve the "HPF" condition for any length of time. Just this past weekend, the flow from the aft overboard appeared to be just spitting and stopping and, within a few hours, all of the units shut down and went into "HPF." Oddly enough, I found that if I ran only the A/C in the aft cabin and turned the other three units off, I could run that one unit without any problems. Yesterday, they replaced the pump and since then all of the units have been running togther without any shutdowns-so far. The reason that I'm somewhat skeptical is that although the forward and mid overboards appear to have a healthier flow, the flow from the aft overboard is quite erratic, shooting the water varying distances and frequently hesitating for a second. It doesn't look right and, of course, as luck would have it, everything will run fine until about 5:30PM on Friday. Any light that anyone could shed on this subject would be welcome. |
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Captain
Posts: 167
Home Port: Pittsburgh, PA
IP Logged | I had a problem with the aft A/C unit and water discharge hose had kink in it where it attached to the thru hull fitting. Had to install new plastic strap to hold hose straight. If i remove head board on aft bed you could gang access to fitting.
Edited by Dbon 8/19/2009 9:05 PM
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Admiral
Posts: 339
Home Port: Solomons MD
IP Logged | Mark, it sounds like your pump may have been an issue. Maybe they found pump impellers broken. The aft A/C has been an issue with me unitl i removed the water hose at the thru hull and cleaned it out and flushed. It appeared that something got stuck on the hose fitting and then started a collection of debris. Cleaned it out first of this summer and have had no problems since. Also, i found out the stain is comming from the sump pump that pumps out that same fitting. It is from the condensate pan of the A/C unit. On the 459, there is access to this fitting thru the cabinet under the back sliding door. |
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Deck Hand
Posts: 23
Home Port: Lindenhurst, NY
IP Logged | Thanks for the input! |
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Admiral
Posts: 442
IP Logged | Do you guys remove your strainer baskets to keep the nettles out?..We will be in fresh water but I've still found plant debris in my strainer basket on current boat. I was told a lot of people just remove the strainers so jellyfish don't clog up the lines?? |
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Admiral
Posts: 1204
Home Port: Clinton, CT
IP Logged | I keep the basket in and check it after the weekend or if there is reduced flow. I certainly would not remove the basket as I would not want to have the debris clogging the units. |
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Captain
Posts: 185
Home Port: Beaufort, SC
IP Logged | I agree entirely with Brian -- The whole point of the strainer basket is to keep grass, critters, and other crud from getting into your expensive A/C system. In coastal South Carolina, where we keep our boat, we don't have a problem with nettles, but we have HUGE growth of grass and all manner of wildlife during the summer months when the water warms up. I find that I have to clean the strainer every few days when we're on the boat (and running the A/C continuously) from June through September, compared to every week or two during the cooler months. When we're off the boat, I generally turn off the two helm A/C units that cool the salon, and leave the two stateroom units set to the "Dehumidify" setting. This runs the compressors only intermittently, and I find that even after a month or so away from the boat during the summer, we'll have only minimal sea growth in the strainer with those settings. The boat definitely gets hot during the day, but the "Dehumidify" setting has been very effective in preventing moisture and mold -- we've never had a problem with that. |
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Admiral
Posts: 305
Home Port: Eastport, NY
IP Logged |
There are external strainers you can install that will help prevent heavier debris from entering your strainer basket. Locally we refer to them as 'South Bay Strainers' because they prevent Eel grass in the Great South Bay from clogging your intakes.
I do not have a picture of them from my boat but the following website has pictures of the rectangular model I have:
http://marineengineparts.com/shopsite_sc/store/html/page87.html
Vic |
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First Mate
Posts: 75
Home Port: Tampa Bay Florida
IP Logged | Planetmark - 8/19/2009 10:51 PM
I'm puzzled as to the whole A/C situation. Last year, when my boat was new, for the first few months the water flow from the aft overboard poured out in an even steady arc. Shortly after, the flow appeared to be flat and somewhat fanning. At first, the only problem that it seemed to cause was the perpetual rust stain. I would clean it and within an hour it would gradually start coming back. Finally, the unit in my forward stateroom went into "HPF" every few days. They blew out the lines several times but, it never seemed to change the flow nor resolve the "HPF" condition for any length of time. Just this past weekend, the flow from the aft overboard appeared to be just spitting and stopping and, within a few hours, all of the units shut down and went into "HPF." Oddly enough, I found that if I ran only the A/C in the aft cabin and turned the other three units off, I could run that one unit without any problems. Yesterday, they replaced the pump and since then all of the units have been running togther without any shutdowns-so far. The reason that I'm somewhat skeptical is that although the forward and mid overboards appear to have a healthier flow, the flow from the aft overboard is quite erratic, shooting the water varying distances and frequently hesitating for a second. It doesn't look right and, of course, as luck would have it, everything will run fine until about 5:30PM on Friday. Any light that anyone could shed on this subject would be welcome.
Hi Mark...Don't know if you are still watching this thread, or if you have seen my thread over in the "Introduce Yourself" forum but here's my take...
It seems that when the system was flushed, that it was flushed just well enough to break loose some stuff...Now it is floating around in the hoses and randomly blocking flow where it now lodges from time to time...
Once the pump shuts off the water drains back, and with it the loose stuff moves...Only to lodge again maybe somewhere else when the pump starts again...
If the water flow does not look right to you (and you obviously have been watching it since new) then it is not right, and will continue to get worse...Changing the pump will not fix a thing unless the pump had a problem...It can only pump water thru unrestricted passages, and that water it can pump will re-direct to the un-restricted passages...Like said...Path of least resistance.
From descriptions here & in the thread I started...It seems the 459 has what I would call a odd or improper A/C plumbing/pump setup...
This happens sometimes with boat builders...Generally speaking...In my experience the only way to get them to make a change in a poor setup is for enough customers to have a problem and complain...No amount of prodding from us A/C guys ever seems to help in effecting that change...It's a shame too because we are the ones dealing with this stuff everyday...They deal with building boats everyday...
So what is the fix ?...Well marine growth will always be a problem but there are a few things that can be done to help...
Over the years the A/C systems that boat builders install have gravitated to the Self Contained all in one units as opposed to the Split/Remote systems that most utilised for years...They don't need guys with refrigerant certification to install or buy these All in One units...They are easier to install, and freon leaks in connections of copper tubing line runs are no longer something they need to worry about warrantying....All they have to do now is run power, water hoses from the pump, and duct...
The problem with this is the water runs are now much further than when the "Central" type systems were installed all in one location close to the pump...Back then we had very little growth problems (just scale buildup in condensers that was easy to remove) and flow was much easier to plan & maintain...
What I have found since this change is that the further, and or higher you pump seawater...The more problems you will have with growth, and it has also created the problems I describe below with using larger pumps...
Directing a pumps flow to units of varying distance & height for even flow to each...Is a challenge to say the least !
Generally their answer is to install an oversized pump in an attempt to brute force flow...
No I have not seen a 459 but it has been described as having two units on the bridge and 2 down below...I don't care how they manifold this setup...It still going to be very hard to get the proper flow to each unit, and the least little restriction can and will upset any kind of balance they have designed into that system...The Pump has to overcome the height (Head) it needs to pump to the units on the bridge so it likely has been over sized just to do that with enough volume for those units...The remaining water can then supply the lower units...
Over sized pumps are never really the best answer over time (though it may be cheaper for them) because a over sized pump attempting to pump thru say four 5/8" condensers (in this case) is (even when the system is clean) likely not pumping it's rated flow which will cause it's impeller to cavitate...This causes cavitation burns to the bronze impeller & pump housing...Thus causing premature pump head failure.
Although it would probably solve the problem...NO, I'm not advocating that the systems be replaced with split/remote/central systems but...
Again having not seen the install...My answer would be to install two pumps...One for the upper units, and one for the lower units...
They both could then be sized for the job presented, the systems & pumps would be much happier with less overall maintenance, and it would be cheaper than replacing/relocating systems.
Steve~
Edited by spcoolin 9/2/2009 11:35 AM
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Air Conditioner raw water flow
