What does it mean when technicians say I have a pitted evaporator on my ice machine?

What is Ice machine evaporator pitting?

When I first learned about this, I was in shock. The tiniest nick on your ice machine evaporator can start causing harvest issues. That nick in the plating is called pitting. What makes it worse is that there are tiny silver colored metal flecks falling into your ice when your evaporator is pitted. Almost all cube ice machines from pretty much every manufacturer have the potential to have a pitted evaporator but it’s not something that needs to happen.

pitted evaporator on an hoshizaki ice machine
Hoshizaki ice machine pitted evaporator

Wait. What was an evaporator again?

Let’s start by defining an evaporator on an ice machine. The evaporator on an ice machine is the area where water is turned into ice. The most economical way to make ice that tastes good is by freezing water as it runs across a plate of metal that gets progressively colder. When the ice is the right thickness on the plate, the plate gets warm and melts the ice off of the plate and drops it into the bin.


The plate is typically made of copper but because copper does not do a very good job of letting go of the ice that is formed, the copper is coated with another metal that will let ice slide off when it is time to melt the ice off of the plate. You probably have noticed that your evaporator is almost never copper colored because it is coated with a silver colored plating that ice easily slides off of. That shiny coating can start to come off of your evaporator for several reasons and when it does it causes problems.

round metal evaporator openings with pitting everywhere
Hoshizaki round cube ice machine pitted evaporator


How does this happen?

How does the silver colored plating come off? Age of the machine can have a lot to do with it. As things age they begin to break down. To make ice, the ice machine constantly has water running through it. If you are maxing out the production of that machine by talking all of the ice it can make in a 24 hour period that machine will run water through it 24 hours a day to keep up with the demand. If you have ever been to the Grand Canyon you find that water is incredibly destructive removing anything in its path. Conversely if you look at the Mississippi River you will find that it deposits as much ground as the Colorado River removes. Both of these are problems in an ice machine that age and break down the machine. To combat this, ice machine manufacturers recommend installing water filtration to remove some of the contaminants that build up over time. Some manufacturers will not warranty their machines unless there is a water filter on the machine. Water that is less harsh is going to damage the machine less and the manufacturers know this from years of experience.


Another thing that removes the silver colored plating off of the evaporator is harsh cleanings. There are a couple of possible reasons why harsh cleanings happen. The first is that a technician may not know what descaler to use and unknowingly begins to dissolve the plating off of the copper by using the wrong one. A lot of repair companies that claim to be ice machine experts are not and they send technicians who cause more harm than good. The second reason that harsh cleanings happen is because too long has passed since the last cleaning and the scale build up is so bad that cleaning scale off takes the plating with it. If you have mineral rich water you will absolutely need more cleanings than somewhere with soft water. Texas water is hard. Don’t wait too long between cleanings or you will be forming your own limestone deposits


The last thing that removes the plating from the evaporator is when people try to pry ice off the plate with a tool or knife and scratch the evaporator plating off. This is not done often but we’ve seen it often enough to warn ice machine owners not to do this. It is an extremely costly mistake and most of the time something simple is wrong with the ice machine causing it not to harvest.

square metal cube evaporator and from a Scotsman ice machine with pitting
Scotsman ice machine with pitted evaporator

The bad news

What is so devastating about a pitted evaporator is that it is not repairable except by replacing the entire evaporator. It’s a time consuming and daunting task to replace the evaporator involving removing a huge portion of the machine to get the evaporator out and a new one in. Along with time is the often extravagant cost of getting a new evaporator from the manufacturer which for some machines makes the repair cost of some older units about the same as a new machine. Ice machine evaporators are very custom and only the manufacturer makes them.


close up of a cube evaporator from a Manitowoc ice machine with lots of pitting
Manitowoc ice machine with pitted evaporator

What can I do to avoid evaporator pitting?

There are two things that you can do to take care of your ice machine and keep it in good condition. The first is to filter the water that goes into the ice machine. We install a filter system on every ice machine that we install and highly recommend them to every ice machine that we clean. It is the first defense against crud getting into your ice machine and building up and causing problems. The second is to regularly have your machine cleaned. It is amazing how much crud builds up in your ice machine. Descaling every six months is recommended for every ice machine to keep it in good working order and to identify problems before they become problems.


Having problems with your ice machine? Give us a call!


Austin: (512) 651-4565

Lubbock: (806) 686-0050


Or check out our website at www.tripointrefrigeration.com


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