I have been living with two of these units for four years, one for a front-loading fridge and the other for a separate freezer
It works great.
Naturally you have to keep them clean, but I lift
& scrub every 3 or 4 months anyway.
It's hard for me to compare with other types, since my last boat was kept in Florida
with much warmer water
, and so a lot more work for the refrigeration
. The water is cool here, so not much of a test.
But I will say that it works so well that you can run it on the hard
without any dramatic loss of efficiency. I have mine in deck
drains, so air circulates past the coils by natural convection, and it works.
Unlike on my last boat, there are no extra sea cocks or sea water flowing around the boat, no pump.
I am very pleased with it.
It is not the "exact same concept" as the Frigoboat system, which is a real keel
cooler with a plate mounted outside the hull
. Frigoboat is highly respected and is original fitment to Oyster
yachts. I think it's probably more robust than Isotherm, as there are no exposed coils. But I would guess that Frigoboat is less efficient. The Isotherm system is supposedly "self pumping" (hence "SP") and supposedly uses any slight movement of the boat to create circulation around the coils. Can't say whether this is true, or hype, but the system works very well. As I said, I am very pleased with it.