Marine A/C Cleaning Procedure

[MicroKap]

I know this has been discussed before. I'm just having a hard time finding the information.

I have 5 split system cruiseair units. Coming off the single water pump, I have a hose connected to a pvc manifold with offtakes for each compressor. At the end of the manifold, there is a single hose that directs the water overboard. I believe I may have to replace a few of the hoses. Currently, most of them are the nylon reinforced clear hose (5/8"). They are no longer clear as you can see a bunch of "crud" in them.

How do you flush the whole system if there are no valves to allow/stop flow of water to each unit? How do you get the chemical to flow through all units? What chemical should I use as I have never done this before and am a little hesitant to use muriatic acid? I understand the whole idea of using a small bilge pump and tap into the manifold input and have another hose return the acid via an additional hose back to the bucket. Also, are there any recommendations on 110 volt pumps since I'm running a 32 volt system and I'm sure a single 12 volt battery wouldn't last for hours without charging from a power source.

Any help would be appreciated.

[MikeP]

For preventive maint I cleaned mine two years ago with 1 part muriatic and 3 parts water using a small bilge pump/bucket, connecting it to each units' in/out in turn. The copper tubing looked brand new/shiny afterward but there was no difference that I could tell in performance. I suppose they could eventually be gunked up enough to matter but to my knowledge, mine had never been cleaned previously.

One thing - if you use a bucket/bilge pump, be sure the bucket of solution is above the condensers. Otherwise the tubes may not fill completely and you can get tubes that have only the bottom half cleaned (same is true if you use that method with a heat exchanger/intercooler - bucket has to be above the HE.

[MicroKap]

What about the cleaning of the PVC manifolds and nylon reinforced hoses? My AC units are stacked, so cleaning the 3 on the top rack may be a little difficult to get a bucket above their level.

[spcoolin]

For preventive maint I cleaned mine two years ago with 1 part muriatic and 3 parts water using a small bilge pump/bucket, connecting it to each units' in/out in turn. The copper tubing looked brand new/shiny afterward but there was no difference that I could tell in performance. I suppose they could eventually be gunked up enough to matter but to my knowledge, mine had never been cleaned previously.

One thing - if you use a bucket/bilge pump, be sure the bucket of solution is above the condensers. Otherwise the tubes may not fill completely and you can get tubes that have only the bottom half cleaned (same is true if you use that method with a heat exchanger/intercooler - bucket has to be above the HE.

I honestly don't know where folks get this kind of info...But you get all kinds of advise around the docks & on forums...Sorry Mike...But that's just not good advise...

If anything the bucket should be below the item to be flushed....You want to fill from bottom to top to push out any air...This way there is solid liquid thru the item to be flushed...Not only that but you would prefer not to set up a siphon effect by having acid above (unless you have a valve you can shut off) in case of an emergency if a hose or clamp lets loose...

Microcap~

I'm not clear on your manifold description...It sounds like you have one manifold that part of the pump's discharge water go's overboard before getting to the units ?

If you replace hose...Black rubber has always seemed to promote the least growth...No light inside & no Vinyl or PVC based hose...Barnacles seem to hold better in that type of hose.

Steve~

[saltshaker]

I'll second Steve's post with regard to the hose. Black hose works fine and has served me well in the same environment as you. Clear hose will definitely promote growth. I'll be down on Saturday, make sure the boat is nice and cool in case we decide to stop by your new slip.

[MicroKap]

I hope the picture I'm trying to attach makes it clearer. The water pump is located along the left side of the picture. First run is up to the PVC along the left side then goes across to the right (under the lower AC units and water pumps), then PVC goes up along right side and has a "T" to facilitate water being delivered from "top" of compressor units and then continues up along right side to service upper compressors. I believe "reddish" hoses are discharges that then go to common drain for overboard. Of course, after looking at the picture for a while, I am now even more confused, but what else is new.

[spcoolin]

Thanks Larry for the picture...But since it's not zoomed out enough it's still hard to tell what's going on there....

I can tell you a few things that might help though:

First...That manifold system is not Hatteras...And the way that it is built...It's very easy for water to bypass one condenser or more, or not feed them equally....Water will take the path of least resistance...

Second...The Cruisair units will have stickers on the inlet & outlets (maybe not still there on the old blue units) but the inlet's are always the lower tubes, and it does make a big difference which way water flows thru the coils....Water enters where refrigerant exits...They run opposite directions thru the water coil/s

Your large unit is over 24,000 BTU and has 2 inlets & two outlets (the reason for that is the tubing only comes so long and can't be joined end to end for the larger capacity units) the inlets will be on the same side (one above the other) same with the outlets...But the lower two on one side will be inlets...

I would say that there is a good chance that all that PVC is full of barnacles...They love white PVC for some reason....

If it were me doing the job, I would try to sell you a new manifold setup with all new black hose...The manifolds I build have removable tops so that they can be cleaned out, but the supply manifold fills from bottom to top so that all hoses get equal flow....The discharge manifold is built large enough that water "Falls" into it & out the side of the boat as opposed to being forced out...Usually the top of the discharge manifold can be removed while running to see or feel water flow from each condenser...All this seems to really reduce growth & increase maintainability...

Steve~

[MikeP]

"I honestly don't know where folks get this kind of info...But you get all kinds of advise around the docks & on forums...Sorry Mike...But that's just not good advise..."

Sorry to disagree but if you clean a heat exchanger using a small bilge pump in a bucket BELOW the HE), the solution will not fill the HE and it will end up cleaning about 1/2 of the HE; the solution will run out the outlet side before the HE is totally immersed and will just keep circulating that way, never reaching higher than just above the bottom of the inlet/outlet. . THe same thing can happen with the tube that forms the ac's heat exchanger though I admit it is far less likely since the pump probably has a lot more capacity than the tubing so it would probably fill the tube regardless.

THe bucket has to be above what you are filling to ensure that the item is actually filled. THe only way this wouldn't matter is if the device has an inlet at the bottom and an outlet at the top BUt something with inlets/outlets essentially level, the item may not fill and the solution will just run in/out at whatever level is the lowest it can manage.

This was covered on the Boat diesel site in some detail several years ago.

[MicroKap]

Steve,
Since I am in NJ and you're in FL, how would you go about "building" a new manifold system for my AC units? Any idea on price. I'm sure I would have to give you measurements, but a rough idea would be helpful. Would your manifold have the ability to "section off" with valves for future cleaning procedures? It would be great if a new manifold was literally remove old and plug in new. What about cleaning of the coils on the compressors still?

[spcoolin]

"I honestly don't know where folks get this kind of info...But you get all kinds of advise around the docks & on forums...Sorry Mike...But that's just not good advise..."

Sorry to disagree but if you clean a heat exchanger using a small bilge pump in a bucket BELOW the HE), the solution will not fill the HE and it will end up cleaning about 1/2 of the HE; the solution will run out the outlet side before the HE is totally immersed and will just keep circulating that way, never reaching higher than just above the bottom of the inlet/outlet. . THe same thing can happen with the tube that forms the ac's heat exchanger though I admit it is far less likely since the pump probably has a lot more capacity than the tubing so it would probably fill the tube regardless.

THe bucket has to be above what you are filling to ensure that the item is actually filled. THe only way this wouldn't matter is if the device has an inlet at the bottom and an outlet at the top BUt something with inlets/outlets essentially level, the item may not fill and the solution will just run in/out at whatever level is the lowest it can manage.

This was covered on the Boat diesel site in some detail several years ago.

Ok Mike~

I'm not here to argue the simple laws of physics...Only to say what I know from doing god knows how many acid flushes....Sometimes I wish I didn't know what I do know...Means I would have had many less of the PIA acid flushes....
I do know that if you fill something from the bottom with liquid....The air in that thing has nowhere to go but out the top....A/C's fill from the bottom & exit out the top....If you were flushing a heat exchanger I would think you'd want to do it the same way...But I digress....Just don't flush your A/C's from the top....Do whatever Boat Diesel said years ago with your heat exchangers if you want...They ARE Your's and they are the expurts on that....

Back to regularly scheduled....Ahhh Hell...If anyone wants my take on the A/C thing come on over to my site...Link at the bottom of this post...

I gotta go out for the afternoon anyway....Another acid flush....

Steve~