lazypup's in the ballpark but I think his long discourse on cavitation is more tailored to an extreme version you'd see in a hot water system. Cavitation occurs at a microscopic level. It happens at points in the pump volute and on the impeller where low pressure occurs (the trailing edge of the impeller is the best example). If the suction head required by the pump to operate is greater than what's available due to suction line throttling or friction losses, the low pressure becomes low enough to cause water to vaporize. It's technically "steam" but not like you think b/c it can happen even at room temperature. This can be exacerbated by pumping a hot fluid b/c it has a higher vapor pressure (i.e. it 'boils' easier). Your pump can be sitting there pumping water pretty much normally and still be cavitating. Lazypup's description makes it sound like you suddenly get a pump full of steam, but that's not the case. The bubbles that are formed by cavitation immediately collapse back on themselves and that's what causes the pump's parts to erode, since the bubbles occur at surfaces in the pump. It sounds like you're pumping marbles. Lazypup's description sounds more like a pump that's air binding. For hot water, it can be an extreme version of cavitation. But what he describes sounds more to me like a situation where the pump is depending on the pumped fluid for some of its lubrication/cooling. If the fluid isn't there, then the pump can quickly overheat.

"Baloney, I don't believe it. What is the source of the information for these claims?" A common example is that water heaters last an average of 1.5 to 2.5 years around here. We're on a water system that runs from 25 gpg to 35 gpg hardness. Replaced my WH in 1995 and still on the same one so that's 7 water heaters I haven't paid for at an average cost of $800 installed or around $5600. My softener cost me around $700 so I'm $4900 ahead... even considering that softener salt cost me about $60 a year... good enough cost offset for you? I haven't has to touch a faucet to fix a drip or open the toilet tank once since 1995. Appliance repair people I know tell me that hard water kills tankless water heaters and front load washers and dishwashers. Oh yea, our dishwasher was installed in 1995 also and it hasn't skipped a beat and the ice maker in my 1995 fridge works great while my neighbors who don't have a softener don't have ice cubes but they do buy bottles and bottles and bottles and bottles of bottled water. People tell me, and my wife agrees, that clothes last significantly longer when washed in soft water. I can tell you that clothes washed in soft water are markedly more comfortable to wear... far less stiff and scratchy. "Some also think it should be plumbed to hot only because the elevated salt level isn't healthy to drink, but opinions are divided on this..." They may think but they don't know what they don't know. No ion exchange softener that is operating properly adds ANY salt to the softened water. Got it, that's ANY salt added. What is added are sodium or potassium ions not salt. So, for you who think, how much sodium (not salt) is really added to soften water? The formula for added sodium is 7.85 mg/l (about a quart) of softened water per grain per gallon of compensated hardness. EXAMPLE 20 gpg * 7.85 = 157 mg of sodium added per liter of softened water, not salt. How does this sodium content of softened water compare to sodium found in common foods? The table demonstrates the usual range of sodium in common foods. Food Amount Mg of Sodium Ketchup 1 tablespoon 204 Milk 2 Cups 226 Frozen Peas 1/2 Cup 295 Bread 2 Slices 322 Corn Flakes 1 oz. 260 Parmesan Cheese 1 oz. 528 Tomato Juice 4 oz. 504 Tomato Soup 1 Cup 932 Chili 1 Cup 1194 Beef Broth 1 Cup 1152 Get a softener and stop eating tomato soup. Softening only the hot water will give you hard water at every appliance and fixture where hot and cold are mixed. You'll pay for soft water and not get it. Any water treatment pro who advocates softening only hot water is either stupid, a scam artist, or to install a softener correctly would be too difficult or too expensive for the homeowner and they don't want to lose a sale (see scam artist). That you don't like the feel of soft water is a valid criticism for some and data suggests that there is an acclamation curve of about 6 weeks and getting used to using far less soap and detergent.

I plan to insulate the wall with at least 2" of styrofoam insulation Then the rest of your questions are redundant. You have to move the plumbing. The pipes have to be on the warm side of the insulation.

My assumption is they would cut the pipes and replace with PVC (or similar) with a coupler of some kind so I'm sure you are correct. The house was built in 1960. Appreciate the info. Will try a quick patch of some kind just to see if possible until it can be fixed.