Flushing marine a/c systems

[MV Wanderlust]

Getting ready to flush the a/c system on our new-to-us boat for the first time. It has three units that are supplied by a single pump and strainer. Seems like it would be easy to

• Premix Barnacle Buster
• Close the through-hull
• Open the strainer and remove and clean the backet
• Have my wife turn the a/c on
• ...while I pour the Barnacle Buster directly into the strainer
• Turn off the a/c and let it sit for a few minutes.
• Put the strainer back in, close it up, open the through-hull
• And let it all flush out.

Seems like I've seen a video on this or seen someone do it... but my memory is faulty.

Okay, stop laughing and please tell me why this approach wouldn't work. What's the easy way?

Thanks.

John

[svHyLyte]

Originally Posted by JohnEasley

Getting ready to flush the a/c system on our new-to-us boat for the first time. It has three units that are supplied by a single pump and strainer. Seems like it would be easy to

• Premix Barnacle Buster
• Close the through-hull
• Open the strainer and remove and clean the backet
• Have my wife turn the a/c on
• ...while I pour the Barnacle Buster directly into the strainer
• Turn off the a/c and let it sit for a few minutes.
• Put the strainer back in, close it up, open the through-hull
• And let it all flush out.

Seems like I've seen a video on this or seen someone do it... but my memory is faulty.

Okay, stop laughing and please tell me why this approach wouldn't work. What's the easy way?

Thanks.

John

To "clean out" your systems, you'll want to counter flow fresh water through them, individually. Normally that requires introducing fresh water at the discharge side and directing the counter-flow into a bucket or overboard on the input side which normally requires the input side line between the raw water pump and the unit be disconnected unless one has a "flush cap" that one can temporarily install one the raw water strainer (see the TRAC Ecological web-site or http://www.cruisersforum.com/forums/...22.htmlinstall for information on the flush caps) although whether this approach would be effective in your case, with a manifold of some type directing raw water to three different A/C units, is questionable. N'any case, once the flushing water through the unit(s) runs clear, you'll want to counter-flow a Barnacle Buster solution through each unit for at least 60 minutes (although longer is better). For most raw water applications, TRAC Ecological recommends a 4:1 solution of fresh water/Barnacle Buster. In most cases, a typical marine A/C unit needs about 1 to 1-1/2 gallons of solution depending upon the length of the feed line between the raw water pump and the A/C unit. You can mix the solution in a bucket into which you place a small submersible bilge pump attached to a hose that's connected to the discharge side of the A/C unit's heat exchanger. The input side of the raw water circuit is connected to a hose that leads back to the bucket. Connect the bilge pump to a power source and let it run for 60-120 minutes, recirculating the solution. Then, direct the discharge to a second bucket or perhaps a sink drain while introducing fresh water to the first bucket until the Barnacle Buster solution has been completely replaced with fresh water. With that your system will be well cleaned out any ready for another year or so of service.

Having 3 units connected to a single pump will make the foregoing somewhat problematic unless you have vales that allow you to close off the feed water to any single unit.

[ranger58sb]

Originally Posted by JohnEasley

Seems like it would be easy to

• Premix Barnacle Buster
• Close the through-hull
• Open the strainer and remove and clean the backet
• Have my wife turn the a/c on
• ...while I pour the Barnacle Buster directly into the strainer
• Turn off the a/c and let it sit for a few minutes.
• Put the strainer back in, close it up, open the through-hull
• And let it all flush out.

Yes, that will work, relatively easily. BUT let the stuff sit for the recommended time period, not just "a few minutes." Could be a couple hours or more. And then I've found it useful to flush (the first time) with new product, let it sit... maybe even repeat again if necessary, depending on what's coming out of your discharges eventually.


Clean the strainer basket and strainer housing first, too, so the product doesn't get distracted doing that for you.

Helps to know in advance how much stuff you need to fill your system. Easily done, I think, with fresh water and food dye. Pump the stuff in until all your discharge ports are clearly showing dyed water. That's the amount of real mixed product you'll want for a single filling.

Sometime in the future you could insert a flush adapter (see Groco SSC with adapter for example) into the plumbing to make it even easier. And a small transfer pump would also push "product" through your system, so in that case there would be no need to turn on the AC pump.

-Chris

[rourkeh]

You have the general idea right but if you use Barnacle Buster it takes hours to really do any good. If your system has a lot of hard growth you could flush the condensor coil all day and not get it clean. I use muriatic acid with an inhibitor that is specifically made for the job. It will not eat the pitting in the soft metal and it removes everything. You need a dedicated pump for this as the acid will eat the internals on a regular pump.
If you want to fix the problem of continuing growth Spectra makes a product that is designed to inhibit growth in A/C systems. It is an in-line cartridge that leeches into your flow and stops growth from starting. It is cheap and works very well. No more major flushing.

[MV Wanderlust]

Some good advice from everyone. Thanks. I've added a couple of steps to the process. One is a freshwater flush. I've also ordered a SeaFlush system and will be letting the Barnacle Buster sit for at least a couple of hours before flushing it out. And I'm going to look into the Spectra BioGuard. Appreciate the advice, as always.

[PwrStkr]

SV Dream Chaser has YouTube video showing how he did his, used muriatic acid.

[wrwakefield]

John,

Also consider aluminum alloy anodes. [Presuming you have a fiberglass boat in salt water and you are protecting underwater bronze and stainless steel...]

They last longer than zinc and are lighter to store for cruising.

This Cruising World article will get you started.

Cheers! Bill

[wrwakefield]

Sorry John,

Obviously my reply was intended for another discussion... More coffee before posting is the new rule for me...

Cheers! Bill