Um... why do you think you have a leak? Refrigerant leak? If it's in the heating cycle the condenser will ice up because it becomes the evaporator. I'm guessing your incoming water is close to freezing? The coil will try to reduce the water temp by about 10 degrees colder in the heating cycle. and warmer in cooling cycle.
Because it's iced up it means the compressor is able to "pull down" the "low side" and you most likely don't need a new unit. You need warmer water coming in if it's not. 42 degrees or warmer.
Hope this helps a little, The difference is only that your using sea water instead of a loop, well, or closed loop in these diagrams.
Thanks for the response Denise.
so you are saying that is normal? Yes it was in heat mode and hasn't been heating as well as it has in the past. The water temp is in the high 50's, I'm at Texoma. I just thought it looked like a leak because it appears to be forming at the top and building up as it goes down. I'm referring to the formation on the left side. I'm no refrigeration guy, that's why I ask. What else could cause it to not be heating as well?
It may be low on refrigerant but that's not a reason to replace it. How old is it? Did it just start heating less?
Check the Water flow through the condenser, blockage of intake, algae in the coil, pump, etc. Check the temp of the water in and out. should be 10-15 colder in heat, and 10-15 warmer in. cool. Also, the coil with the fan should have about the same temp differences.
If you have the unit information, we can possibly find a temp/pressure chart unique to your unit and we wouldn't have use "rule of thumb" parameters. 410A or R22?
If you put it in the cool cycle the ice should melt. You'll also want to make sure the H/X isn't split from the ice too.