The concept of pressure as it relates to the residential water distribution system is without question the most miss-understood topic in all of plumbing. We constantly see questions posted regarding pressure and invariably someone will suggest going to Lowes or Home Depot and getting one of the little pressure gages with a hose thread attachment, then measuring your line pressure, as if that would yield any usable information. In truth, those gages only read "Static head pressure" which is the pressure on the system when all valves and faucets are closed and there is no flow, however, the performance of your showers or fixtures is dependent upon "Dynamic Pressure" or what is more commonly known as "Working Pressure" or "Flow Pressure". In order to effective measure dynamic head pressure we would need to install a Tee at the point where the fixture is attached to the water distribution system and measure the line pressure as the water passes the gage and into the fixture. IN one of my previous posts I described how the static head pressure on the municipal main can vary by changes in elevation. The same is true of the water in your house distribution system. Let us consider a two story house where the water main is located near the floor in a basement. While we may measure 45psi static head pressure at the main we must remember that the water will loose 0.434psi per vertical foot of rise. This loss is technically defined as "Vertical Static Head". In addition to vertical static head we must also consider the "Friction head loss" which results from friction between the moving water and the internal wall of the pipe. Thus "Dynamic Head Pressure" can theoretically be estimated by computing the vertical static head loss and the friction head loss, then subtracting the losses from the static head pressure at the main. let us put this in perspective. Imagine a house where the water enters the basement 1' above the basement floor and the basement has an 8' ceiling. We have a 7' rise to the ceiling, then a 1' rise for the floor joists and flooring material on the 1st floor. Now let us assume the house has 9' ceilings on the first floor and another foot for the floor joists to the second floor. We then have another 6' rise from the 2nd flr floor level to the shower head so our combined vertical head loss is (7'+1"+9+1'+6") x 0.434psi = 24' vertical x 0.434+ 10.416psi vertical static head loss. This means that if you had 45psi static head pressure at the main you would have 45psi - 10.41psi vertical static head loss = 34.59psi at the shower head. From this we must then deduct "Friction Head loss" however, computing friction head loss is not nearly as simple as computing vertical static head loss simply because as the velocity of flow increases on a pipe, the friction head loss will increase proportionally. now let us imagine that the water main is at the front of the house but the master bath is at the rear corner where we would have a 50' horizontal run of pipe plus the 24' vertical rise for a total of 74' of pipe. If we were to be precise we would need to also compute the fitting insertion loss for each fitting on the run. By example, a 1/2" elbow has a fitting insertion loss equal to .9 feet of pipe. W could compute all the fitting losses or we can rely upon the code approved standard of allowing an addition 20% for the pipe length. Thus our pipe length is now 74' + 20% = 1.2 x 70= 84'. Now let us imagine the we have a 1/2" copper pipe running directly from the main to the master bath. Now let us consult the copper pipe friction head loss table. In a 1/2" copper pipe with a flow rate of 1gpm the friction head loss is 0.008psi per linear foot of pipe thus the friction head loss to the master bathroom at a flow rate of 1gpm would be 84' x 0.008psi= 0.672psi. Not enough to really be concerned with, but let us examine what happens if we turn on the shower at 2.5gpm and the lavatory at .5gpm. The flow is now 3gpm and the friction head loss is 0.161psi per foot x 84' =13.54psi friction head loss. In this example, even though we had the code minimum 45psi static head pressure at the main, because the line was improperly sized to the master bath the resultant "dynamic head Pressure" at the shower would now be 45psi minus (10.41 vertical static head loss + 13.54psi Friction head loss) or 45psi - 23.95psi loss = 21.05psi. Even this would not be a big problem for conventional shower mixers because they are rated to perform with a minimum of 8psi and a flow rate of 3gpm, however, we commonly hear complaints from homeowners that they did a remodel on their bathroom where they removed a conventional mixer and replaced it with a pressure balancing mixer. A pressure balancing mixer requires a minimum of 20psi dynamic head pressure at a flow rate of 3gpm. From our example you can see that the new shower mixer requires 20psi while we only have at best 21.05psi available. Needless to say, if anyone were to run water anywhere in the house, the resultant pressure to your pressure balancing mixer would not be sufficient for it to operate properly, and sadly enough, most people get on the phone to the mixer dealer or manufacturers complaining their product is no good. Please believe me when I say, there is no guesswork in plumbing and although you may feel confident that you will save a pile of money by doing it all yourself, this is a prime example where you really should consult the services of a plumber, if for nothing else but to plan your layout. This is also why in most jurisdictions you may perform maintenance on a system without pulling a permit, but all new work, whether it is building a house from scratch or simply doing a major rehab requires all the proper computations and pulling a permit before the work may commence.

The directions that came with my Kohler fixtures said to take out the restrictors and remove the shower head, and then run the shower for several minutes to ensure all the junk was out of the plumbing lines. I put the restrictors back in, and all the shower heads seem to work really well. The Kohler faucets seem to be another story, since I followed the same process and they flow quite a bit less than my other faucets. YMMV Bruce

Building a shower pan that doesn't leak can be tricky. Keep in mind that if it leaks, the only remedy is ripping out all of your work (tile, base, everything) and starting over. You want to make sure you get it right the first time. There are some excellent YouTube videos that you should watch, even if you aren't doing the work yourself. It will clue you in what to look for. Watch several of the videos so you get a good feel for the right way to do it. There's also this video that talks about a job gone bad. Some of the other issues involve sloping the curb towards the shower (not level), making it the proper width to avoid unnecessary grout lines Note the use of Red Guard, and the correct gap from the wall board to the floor. BTW: If after watching these videos, you see your contractor doing the wrong thing - stop him and have a conversation. You seriously don't want this to be wrong - because it will usually only become apparent several years after he's been paid.

"even from a “certified” Schluter installer" There is no such thing. A 19 year old that works sales in a tile showroom can attend a 2 day Schluter seminar. Sleep & text through 50% and get a certificate even though they have never even installed a piece of tile in their lives. Do you really want to hire that person for your project. They do a nice job with the seminars as I have attended multiple times. If you had a Schluter employee come to your home that would be a different scenario. I often see on this forum folks claiming to be Schluter certified. Just not the case. Always hire wisely. uscpsycho - Keep in mind there are many heat systems on the market. NU-Heat, Laticrete, Warm Floors etc. Research and compare products. Don't let $$$ spent on marketing make up your mind. Often there is better for less $$$.