Here 'ya go....
Copied over...
Ok, I've been refining this process now for a couple of years, and am ready to share it with the forum...
This works for ANY heat exchanger that can be isolated - genset, engine primary, transmission, and your AC system!
You will need:
1. Inexpensive 500gph bilge pump with a 3/4" outlet. 20 feet of 16ga wire and a lighter plug (or suitable means to connect it to ship's 12V power)
2. About 15' of 3/4" hose.
3. A 5 gallon bucket.
4. 1 gallon of Ph-Ospho-RIC (from Home Depot, found in the paint department - about $13) This is phosphoric acid and a detergent.
5. Chemical resistant gloves and safety goggles are highly recommended.
To clean the H/E:
1. Close the seacock going to the H/E you intend to clean.
2. Remove the hose connections to the H/E. If it is a genset or A/C unit, there is a good chance the connection is 3/4" hose. If so, you're in like Flynn. Mains will have a larger hose inlet typically; 2" is popular.
3. If the inlet is up to 1", you can get nylon hose-barb adapters at most hardware stores to adapt 3/4" to up to 1". Buy the ones you need for your specific H/Es once. If the inlet is LARGER (e.g. 2") take one of the hoses to Home Depot or Lowes and come up with the PVC fittings to make up an adapter; 2" hose, for example, uses a 1-1/2" PVC coupler, a 1-1/2 to 3/4" threaded adapter, and a 3/4" hose barb to MIP nylon adapter. Fit up the pieces dry in the store and buy what you need. PVC fittings require PVC cement. Make up the fittings you need to adapt to the hose sizes in question.
4. Connect the output of the bilge pump to the OUTLET of the H/E using the adapter if necessary and half the 3/4" hose. Take the other half and connect it to the INLET, and run the hose back into the bucket. Place the bilge pump in the bucket. THE BUCKET MUST BE ABOVE THE H/E YOU ARE CLEANING TO INSURE THAT ALL AIR WILL BE EXPELLED.
5. IMPORTANT: Remove all zincs from their plugs, and reinstall the BARE PLUGS. DO NOT LEAVE THE ZINCS IN THE HEAT EXCHANGER!
5. Add roughly 2.5 gallons of clean water (half full). Turn on the pump and insure that the pump retains prime while circulating the water.
6. Add approximately 1/2 to 3/4 gallon of the Ph-Ospho-Ric to the bucket.
Allow the acid to circulate through the H/E until the foam and bubbling on the surface of the bucket's liquid STOPS. The amount of time this will require depends on how badly fouled the H/E is; it is not uncommon for this to take an hour or two. Phosphoric acid will "parkerize" steel and iron along with removing all the rust (a good thing!), and will ignore the cupero-nickel used in heat exchanger bundles. It will dissolve the organic, mineral and salt deposits, which is what you want. The solution will turn dark as it works. This is normal.
When the bubbling stops, turn off the pump. Drain the solution back into the source bucket.
Reconnect the original hoses and immediately start the engine or other device, allowing it to run, to flush any remaining residue out of the system.
Make sure to flush the hoses and pump with clean water when you're finished, and reinstall the zincs in the plugs.
You're done.
The solution can be reused several times. When done with it, you can use Baking Soda to neutralize the acid before disposal.
NOTE: Phosphoric acid contains phosphorus, and should NOT be dumped in the water as it is an algae nutrient, even after being neutralized with baking soda.
This procedure has several advantages over the other possibilities:
1. Its quick. I can do both mains, the genset, and the AC system in a day, and during most of that I can be doing other things as its all pump work time. Dismounting H/Es or disassembling bundles is quite a bit more work and in many cases requires draining the freshwater side of the system.
2. It is a LOT safer than the DD-recommended Muriatic/Oxalic acid solution. Muriatic acid is a MAJOR hazard if it spills - especially on you. Phosphoric acid is much less dangerous to handle. In addition, Muriatic acid causes hydrogen embrittlement of metals over time, which Phosphoric acid (mostly) avoids. If you leave the Detroit solution in too long, it will do damage. This is much less likely with the Ph-Oshop-Ric.
3. It works just as well as the DD recommended solution, if not better. You can confirm this with a flashlight - and your temperature gauge - after doing the deed.
Once you've made up the adapters, this is a very quick and easy maintenance procedure to do annually, which will keep you from having overheating problems during the season.
Any questions, feel free to post 'em and I'll try to respond...
Enjoy!
