Originally Posted By: 4wheeldog
Originally Posted By: Kestas
Originally Posted By: zach1900
I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.
You're thinking of deionized water. It tries to strip metal from its base surface. But this phenomenon goes away the minute you splash antifreeze or dirty water into it. Use distilled or deionized water in your cooling system with confidence. I do.
We have deionized water on tap at work. I use it in all our coolant systems that produce swarf.
Don't use rain water. It has too much carboxylic acid in it.
What he said.....
I went to a boiler class years ago. The guy giving the class explained why deionized water was bad in boilers. He called it "Hungry water". He then tried to make the case that the same was true in your car's cooling system.
I waited until lunch to quiz him on this, and after lunch he amended his statement that, if you were not using antifreeze, deionized or distilled water were poor choices. With the use of 50% antifreeze, "Hungry water" has its needs satiated.
I see why your boiler feed water guy said what he said then after he thought about it modified it a little bit.
Let me give you guy’s a little more detailed information necessary to see what the best answer is in your particular situation. (when I design an HVAC/R system or do boilers this is critical because the industrial systems are radically different than the automotive systems and I have to explain it a lot because there’s a lot of maintenance guys out there who have innocently destroyed an industrial system because they tried to use automotive information thinking it was a 1:1 swap- it isn’t)
First off the “question” of tap vs. Distilled vs. DI etc. is wrong coming out of the gate because at that level it is not answerable.
It’s not a question- it’s actually an equation that will determine what the acceptable is for a specific cooling system. Even then the term “acceptable” has to be further defined because there are too many variables in the alphabet soup for a universal answer. This is why on industrial systems we also have to spec out the water quality standard based on system metallurgy and the selected coolant chemistry and other stuff for optimum performance.
If you define “acceptable” as the ability of heat exchange then all waters are identical.
If you define “acceptable” as long term efficiency and reliability in a system then you have to do some extra thinking and get some additional information. You also then need to factor in external factors such as maintenance intervals, system load and so forth. (This is where there is a fork in the road with what I do versus what a car owner will do because nobody “drives” an industrial HCU and they always run at a constant set of operational parameters and the fluid is tested frequently for system specific data points)
Basically water falls into a few basic categories and each have properties unique to it, random elements and other stuff. DI, DS (distilled), filtered, tap (city water) and ground
Everybody pretty much knows the differences but in basic terms DS is demineralized, DI has lower conductivity, tap, filtered and ground contain whatever they contain based on however they were processed.
Then you add the system metallurgy (some chemicals attack certain metals), the individual chemistry of the selected coolant, and sometimes even factor in transient electrical current from ungrounded components and there is a potential for damage. How much would depend on which part of the formula is affected and to what degree and whether the maintenance routine will mitigate it. You also can do things like sacrificial anodes and add buffers if required.
Not ever even thinking about testing a car system, if it were me, unless the antifreeze or car specified a specific recipe (which if they do they have a reason for it) then with a normal coolant maintenance program I doubt anyone would ever notice a significant difference in performance or reliability unless your water source was extreme in some random area of the equation.