Winterizing - water system

Posted on 07 October 2009
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The primary objective in decommissioning potable and cooling water systems is to prevent damaging freeze-ups in colder climates. The surest way to do this is to completely drain all water from the systems. If that isn't possible, the addition of non-toxic antifreeze is the safest and most reliable method of prevention.

Unfortunately, the level of protection offered by antifreeze solutions is often misunderstood. The quoted level of protection - "down to -50 F" - is derived from residential construction standards and is intended to mean that copper pipes will burst when the antifreeze in them reaches that temperature. The "-50 F" is a failure point, not a protection point.

The danger is that the plastic pipes, filter housings and pump bodies in marine use will be destroyed long before that level, so it's important to choose the type and strength of the antifreeze solution. You must assume that some water will remain in the system, which will dilute the antifreeze and raise its freeze point. The extra cost (about double) of "-100 F" antifreeze can be inexpensive insurance.

Here are some important points:

Return to The Soundings Boat Shop Complete Guide to Winterizing.