it was recommended to me (and I have old vintage 1940 fixtures) that as I have escutcheons on shower handles, to take the escutcheon off, and put a "frown" or "rainbow" (basically a semicircle) of caulk above the pipe coming out of the tile, but within the circle of the escutcheon (so that it's hidden), and let that line of caulk dry, and replace the escutcheon. Reason is, water that gets behind the escutcheon will hit the dried semicircle of caulk adhered to the tile, and will roll off the sides, and won't get into the hole in the tile. When it rolls off, it will drip out the bottom of the escutcheon. What you don't want is a full seal around the whole bottom of the escutcheon, as this can lead to trapped water in the escutcheon if the caulk fails on the top or sides. Many of these escutcheons deliberately have a drip hole to let water out.

I am a DIY'er and did a pretty significant bathroom remodel where I did all the tile work. On my shower, I used Laticrete Hydroban and durock for my walls. At all corners and at the tub flange, I used fiberglass tape embedded in thinset, sort of like your video. Much cheaper I imagine. The Schluter Band is water and vapor proof I believe. You will be using Redgard to achieve the same water management goal, so I don't believe you would need the Schluter product. All changes of material and planes will be covered with the fiberglass tape and thinset. All the fasteners will be covered with thinset. All valves are set with tape and thinset, or the product included with the valves. My valves came with a taping product that I thinset into place. Then everything is coated in the water management membrane such as Redgard or Laticrete. I filled in all small voids with thinset. I don't have a picture of the bottom of my shower pan and Durock, but I think I taped it with the fiberglass tape. It has been some time since I did this job. Below, is my thinset and taped cement board. True Confessions, I don't think I have enough fasteners, nor the right kind, in my wall, and I worry about this flaw in my shower. I had drywallers hang this for me when they did the rest of the room. I assumed they used the correct fasteners, but they didn't. They started out with galvanized nails, which I believe would have been ok, but I wanted screws, so they switched to the drywall screws. I had the Durock screws, but didn't give them to the workers, assuming they had their own. They didn't. So after they left and I saw the, I tried adding my Durock screws into the wall. I couldn't do it, I just wasn't strong enough. DH was out farming and wasn't available to drive more in for me. So I proceeded. My mistake, as I learned later the drywall screws deteriorate in cement board over time because of the alkaline conditions. I confessed to DH that the walls might fall down in a few years. He said, "well when they do, we'll just fix it." What a relief I felt, I no longer carried this burden of knowing that I flubbed up: Here is the bottom where the coating is onto the shower pan. It hard to see, but the pan and walls are totally sealed in the Hydroban. Click it open to see the bottom of the walls at the shower pan, where I taped a plastic sheeting to protect the pan. Be sure to follow the recommendations for thickness with your Redgard. This is Laticrete Hydroban: If you click the picture open you might be able to see the valves sealed with the Hydroban. This green tape is by 3M and is very strong used for taping concrete I believe. It was great to use to hold hanging tiles into place until the thinset cured. You will want this tape for your tiling job, I loved it:

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.

Argh -- I was hoping that a power vent of the exhaust gas would be sufficient to solve the problem, and that I wouldn't necessarily need a direct vent of outside air for combustion. Just having a power vent of the exhaust gas would be easy to retrofit into our system, and as a big added bonus, the power vent systems seem to be incredibly energy efficient. Having a direct vent for the combustion from outside air would be more difficult to retrofit in, and such systems for whatever reason don't seem to have as high energy factors as the power vent-only designs do. I'm thinking that perhaps I may just permanently disable the exhaust fan. The exhaust fan helps in late spring early fall when the outside temp in Phoenix swings from high to low greatly overnight. In the summer time, it doesn't help that much, since the outside temp stays hot all the time. I already have radiant insulation on the inside of the garage door (we're south facing), which has greatly assisted in rejecting heat from being soaked into the garage. Alternatively, I may look into solving the negative pressure situation. Presumably, I could cut more holes into the walls of the garage, and then verify that the exhaust gases are not being sucked out of the flue. I'm thinking I may just be on the threshold of the negative pressure situation, insofar as the problem does not occur all the time. On the flip side, I don't really want to start cutting holes into the walls of the garage willy nilly unless I know it's going to solve the problem.