Fischer Panda Cooling System Modification

Fischer Panda (FP) Generators are now cooled by fresh water and the sea water only passes through the heat exchanger and then out via the exhaust hose. BUT it didn't use to be that way. My  FP is around a 2001 model, 5.5KVA. In my FP the cooling is done with sea water, which first goes around the generator casing and then to the heat exchanger, before exiting via the usual exhaust method. The fresh water gets circulated around the engine and through the heat exchanger to get cooled from the seawater that has picked up a little heat from the generator casing.
You can see the heat exchanger situated underneath the generator in the picture below. I consider that poor design and changed my heat exchanger location which you can read about here and also here
To change my cooling system, I figured it was only a case of changing a few hoses over and I could have both my generator casing AND my engine cooled by fresh water and use the raw water only for cooling through the heat exchanger. Read below how I did it...

FP blurb about their water cooling.

First I removed the freshwater hose that went from the engine to the heat exchanger. You can see the fresh water hose coming from the pump (above generator belt) to a metal tube which then does a small bend and goes down and sits just behind the Johnson raw water pump. The removed hose is sitting in front of the pulley.
Next I removed the hose from the raw water pump which goes straight down to a pipe that dives under the motor to the generator casing.
The idea is to swap these two over. Fresh water will now go to the generator casing, and raw water to the heat exchanger.

In the picture to the right, you will now notice, the pipe that sat under the raw water pump has been moved to the right a little and hooked up with the fresh water pipe coming down from the fresh water pump. (pump not seen). I had to cut about two inches (50mm) off the pipe so that a hose will connect.

I had this 20mm pipe (in picture to the left) made for this change over.

In the picture to the right, you can just make out the curved pipe as it is now attached to the raw water pump and the pipe continues to the heat exchanger underneath the pulley.
Now, at the heat exchanger. the pipe that use to be fresh water is now raw water and should be connected to the raw water input at the heat exchanger.... AND the raw water input hose at the heat exchanger is now fresh water. Just swap the two over.
So, lets follow the path of the fresh water first.
From the fresh water pump, it goes down beside the crank pulley and dives under the motor to the generator casing. From the generator casing, the fresh water goes to the heat exchanger to be cooled and then returned to the engine at the header tank. From the header tank, it gets circulated around the engine and repeats the cycle.
Now the raw water.... It leaves the raw water pump and goes straight to the heat exchanger; picks up the heat and then exits via the exhaust. Just like the new FP's.

Finale hookup with generator belt back on.

  BUT, that's not the end of it. You might imagine that the generator casing may have some internal salt deposits. So, I first ran the engine up with fresh water to temperature and then after cooling down some, drained that water  away. I then did another run up using a product called "Salt-X". I mixed with water as per directions and repeated the draining of the fluid after cooling down some. This Salt-X is a produce for removing salt deposits in outboard engines and should be available in most marine Chandler stores. Finally, I did another fresh water run up and emptied that too, before using a ethylene glycol "antifreeze/antiboil" product. I'll change that in about 9 months time as well; to make sure all salts that remained have left the cooling system.
We also have a fresh water flush system for both our engine and Genset. As we get ready to shut them down for a while, we open a valve to our fresh water tank and close the sea cock. We let the engine run for a minute or two and this then flushes out the seawater from the heat exchanger. Thus prolonging the life of the heat exchanger. Then, after shuting down the motor, it is important to close that fresh water valve; otherwise, the next time you open the sea cock, it can back pressure to the fresh water and ruin your tank supply. It usually only happens once. :-D
All up, it took about 2 hours and a ten dollar item to complete. Antifreeze and Salt-X were extra costs; but you should replace you antifreeze once a year anyway. It's mostly for the anti corrosion properties that we use it.The engine actually runs slightly cooler, and with a trip up to the tropics soon, will be beneficial.

Heat Exchanger Modification

After installing a new heat exchanger for our Gen Set, we had no further issues. However, the primary issue of "stuff growing inside our heat exchanger" has not been resolved, and, because the Fischer Panda generator has it's heat exchanger in such an awkward place to service, we decided to modify our new heat exchanger so that it can be cleaned out with the minimal of fuss annually.

  We took our heat exchanger and removed the ends by "unsoldering", so that new ends could be attached that would allow for easy removal.
We attached some brass ends (by soldering) with a reducing thread and then used a threaded cap, and finally a threaded tail to give us our 19mm hose fitting.

In the picture to the right, you can see how easily it is now to remove the end caps to clean the internals of the heat exchanger. And with it's new mounted location, we should no longer have issues with our Gen Set shutting down to over heating.
Since we have been dealing with heat exchangers, we have learnt something. Heat exchangers made from copper and nickel last a lot longer than those just made from copper. All heat exchangers should have some provision for cleaning the "internals". A sacrificial anode is a must. A fresh water flush through the engine and heat exchanger before turning the engine off for prolonged periods, increases the life of the engine and heat exchanger.

Heat Exchangers; Somethings to consider for cruisers

For most people traveling in "well to do cruising shores", usually have the means to obtain spares quickly. There are some areas though where spares are hard to get, or if freighted in, present customs difficulties; let alone the cost of it all. So, most cruisers carry what they think they will need. We thought we had most areas covered, but when we arrived in Fiji, we had three of our four heat exchangers go bad in less than one month. The transmission heat exchanger had small pin holes which leaked sea water. This was easily fixed with some solder. The main engine heat exchanger presented itself to my wife and I, by us noticing we were loosing engine fresh water from the "small top off tank". We suspected the fresh water was being lost through a hole inside the heat exchanger to the seawater side. Fortunately I had a spare main engine heat exchanger and replaced it out. The old one was sent for cleaning and testing and our suspicions were confirmed by the engineering firm. A small leak inside the heat exchanger.
(BTY, we hunted for a heat exchanger of any kind and could not find one in Fiji. We knew there would be some place that had one, but we felt we were chasing our "tails". So we went to plan "B". Get one where we know we can source one. Read below.)
The last heat exchanger was on the generator. A Fischer Panda (FP).

You will notice the round heat exchanger, under the motor and bottom hose. Just looking at it, I figured that it is going to be one hell of a job to get that out. We reversed flushed the heat exchanger, and got out a handful of particular matter. Inquiries, told us that this stuff actually "grows" inside and even though we fresh water flush the generator after each use, (flushing out the seawater from the heat exchanger) this wasn't enough to prevent stuff growing and blocking the tubes inside the heat exchanger. The flush worked for a while and the generator ran for some weeks, before it started to over heat again.
So, leaving the FP heat exchanger where it was, and removal for a time when we are in a better location, I decided to install another heat exchanger, out side the casing, and one which I could easily get to the hoses and heat exchanger itself. My wife was making a quick trip back to New Zealand, so I had her procure through contacts, a heat exchanger. This was modified with the appropriate hose tail size to fit the hoses used on the FP. I was very lucky to have someone help me with this while I sat in Fiji. Needless to say communication was a major factor in getting this done. Many thanks to Charles Webster.
When, the unit arrived, I set about modifing the cooling system for the new heat exchanger.

The parts, were carefully checked to make sure I had everything. The 19mm radiator hose is not shown in the picture but I had 4 metres of the hose.
The fresh water and raw water side of the FP heat exchanger were identified  and the existing hoses removed from the fittings at the appropiate end. ( the other end was left attached to the FP heat exchanger, making for an easy reversal if needed.) New hoses were run to the outside of the FP casing, by which I had to drill 3 new holes in its base. The new heat exchanger was mounted to a cross member that sits behind the FP and in front of the main engine. The hoses were hooked up and the generator started. I'm pleased to report that the generator now runs for some hours and the water from the exhaust is no longer very hot but is warm to touch and the unit no longer shuts down itself due to over heating.

Some things to consider. I knew the FP heat exchanger was in poor location and if I ever get it out, will probably put removable end caps on it and mount it outside the sound proof casing just like the new one.
The new one works great, but in the next time the boat is laid up, I might also remove, (and now very easy to do so) and have it modified with removable end caps of a screw off nature.
I'll carry more heat exchangers as spares.
I'll carry a propane torch, easy flow rods, and silfos rods. Solder and soldering iron I already carry.
I will always consider the cost of an airfare to be part of my spares, to procure the item I neglected to have the foresight to carry.
As a bonus, the FP now shuts down from the control panel quickly, and I may remove the second solenoid modification, detailed in a prior blog, because it is not needed and the whole issue of not shutting down may have been due to a protective system in the control module. I'll give it another couple of months yet to see if all is well with the shut down. How do your heat exchangers look? Can you clean them easily? Happy cruising!