Isotherm Compact SP experiences

[Orion Jim]

I am considering the purchase of an Isotherm Compact SP water cooled through hull refrigeration system. My boat was never equipped with a refrigeration system so this is a new installation. I have already added one inch of R6 closed cell foam to my existing ice box and I have lined the ice box with 1/8” fiberglass sheet painted gloss white. The result is a well insulated box of 3.8 cubic feet.

What have your experiences been with a water cooled through hull system....preferably an Isotherm system?

[model 10]

We used that system for 10 years with no problems. There came a leak in the system, the refer tech hated water coolers, so he installed a air cooled condenser. It wasn't the problem. It was a spot on the evaporator line that had chafed a hole.
If the boat never moves, there is no water movement in the sink drain, but that's not much of a problem. The condenser is right at the thru hull and has the whole ocean to cool it.

[toddster8]

I’ve had the compact Isotherm air-cooled unit installed for a season now. My ice box is a About 4 cubic feet and has the original 1970 low-density foam insulation, except there was none on top, so I glued an inch of high-density foam under the top and lid. And put a valve on the drain hose to stop cold air from dumping into the bilge.
When the weather is hot (ca. 100°F) the unit runs for about five minutes and rests for about 15 minutes. Current draw is about 2.6 amps. The batteries can handle it for days on end without recharging. The unit is installed in the sail locker just on the other side of a bulkhead from the icebox. There is no audible sound inside the boat, except a small “click” from the thermostat when it trips. Sticking your head into the sail locker, you can barely hear the fan.
Cold drinks all summer without schlepping ice. Very happy.

I should add that at the location where the condenser unit is installed, suspended on its bracket in the mechanical area, near the waterline, it naturally draws cool air up from the aft bilge and warm air exits out a vent higher up on the coaming. When I put my hand in front of the fan, I feel cool air (not warm air) coming out.

[Richard Kollmann]

Originally Posted by Orion Jim

I am considering the purchase of an Isotherm Compact SP water cooled through hull refrigeration system. My boat was never equipped with a refrigeration system so this is a new installation. I have already added one inch of R6 closed cell foam to my existing ice box and I have lined the ice box with 1/8” fiberglass sheet painted gloss white. The result is a well insulated box of 3.8 cubic feet.

What have your experiences been with a water cooled through hull system....preferably an Isotherm system?

There are two problems with Isotherm's thru-hull refrigerant seawater condenser you should be aware of, it is not self cleaning and its corrosion control zinc requires frequent maintenance on boats not equipped with isolation transformers.

[model 10]

Originally Posted by Richard Kollmann

There are two problems with Isotherm's thru-hull refrigerant seawater condenser you should be aware of, it is not self cleaning and its corrosion control zinc requires frequent maintenance on boats not equipped with isolation transformers.

That was not my experience. The zink looked great after 10 years and would do another 10 years. We have no transformer and the thru hull is bonded to the boat. I was always impressed at how clean the condenser coils stayed. I think some of the galley soaps etc kept it that way.

[Auspicious]

I have 13 years on an Isotherm SP. I think I predate the Compact line. I have one for a fridge and one for a freezer. They've been great. Very quiet and quite energy efficient. Much better in those respects than air cooled. In addition, unlike keel coolers, they work while on the hard long as you remember not to leave a plug in the sink drain. Power consumption goes up but plugged into shore power on the hard that doesn't matter.

[WSMFP]

Originally Posted by toddster8

I’ve had the compact Isotherm air-cooled unit installed for a season now. My ice box is a About 4 cubic feet and has the original 1970 low-density foam insulation, except there was none on top, so I glued an inch of high-density foam under the top and lid. And put a valve on the drain hose to stop cold air from dumping into the bilge.
When the weather is hot (ca. 100°F) the unit runs for about five minutes and rests for about 15 minutes. Current draw is about 2.6 amps. The batteries can handle it for days on end without recharging. The unit is installed in the sail locker just on the other side of a bulkhead from the icebox. There is no audible sound inside the boat, except a small “click” from the thermostat when it trips. Sticking your head into the sail locker, you can barely hear the fan.
Cold drinks all summer without schlepping ice. Very happy.

I should add that at the location where the condenser unit is installed, suspended on its bracket in the mechanical area, near the waterline, it naturally draws cool air up from the aft bilge and warm air exits out a vent higher up on the coaming. When I put my hand in front of the fan, I feel cool air (not warm air) coming out.

I'd back this up by saying I have a air cooled isotherm 2501 system from west marine and it works very well even in Florida summers. I'd go air cooled. The newer stuff is very efficient.

[chouliha]

We had one that we installed about 20+ years ago. It worked great and about 8 years into its life the water cooled heat exchanger sprang a leak. We replaced it with an old oil cooler in Australia. It worked better than before. Before we departed on this trip in 2004 we thought crap its so old better replace it. We purchased a new Isotherm water cooled system as it fit in the same footprint. Within 2 years every Isotherm part of the system failed and we finally pulled off all the Isotherm stuff and ran it bare bones. Now we run it without a thermostat and use a 12V multi stage timer. We have 3 settings based on water / air temps. The current Compressor is 15 years old

The big issue being overseas is that the normal refer guy did not have the parts to repair Isotherm add ons and we would have to order from the US and we would have to deal with foreign customs

One of the things we did with the older unit and continued today is run the water cooling thru the fresh water tanks. Never had an issue with growth in the filter or an issue with zincs. Plus runs perfectly in the yard

So basically the unit is now 100% Danfoss BD50 with an electronic Danfoss brain.

Would we buy another Isotherm - Not after the experience we had previously and think we would look at other options

Good luck with your choice

Chuck
Jacaranda