The auto fill valve should be isolated and cut off from the system after the system has been filled to the correct pressure level to maintain a âÂÂclosed systemâÂÂ. Likewise the expansion tank should be inflated to its correct value before being connected to the system. Is this 40psi reading with the boiler stone cold or hot, with the circulator running or not? Has the circulator been recently replaced or operation modified? I think you have to isolate the auto fill valve from the system anyway to determine on which side of that auto fill valve the high pressure is coming from. It seems like you may have full water line pressure from the city in your system. How many floors is the building (how many feet high)? When you say, âÂÂfrozen boiler pressure relief valveâÂÂ, do you mean frozen or seized? Does the system have some sort of auto air elimination vent? SR

No you don't have to shut off the supply water before the pressure reducer. If that were the case why have a pressure reducer at all? You could just fill the system according to the reading on the pressure/temperature guage. Westminsterbergs, are you sure the PRV is the problem? Whats happening, is the pressure in the system building up to the point that the relief valve is blowing? Has anyone checked the condition of your expansion tank? Do you get your domestic hot water off the same boiler? If so you might just have a pinhole leak in the tankless coil thats slowly introducing street pressure into your heating system. In the average house the heating system pressure should be no more then 12 PSI. You have to supply more information before anyone can give you an educated answer about your problem.

Although its not impossible, I doubt seriously if you really have a 5/8" diameter copper water supply. Code minimum for any water supply is 3/4", however you may have a 3/4" copper water line with a 5/8" water meter, which is very common in residential structures. As the water flows through a water meter it turns a small paddle wheel which is mechanically coupled to drive the measuring instrument. For many low volume applications the code mandates that we install a meter that is slightly undersized. It does not effect the volume of flow, but as the volume of water passes through the reduced diameter it increases the velocity of flow through the meter, which in turn increases the velocity of the paddle wheel and it results in a more accurate reading. There is a minor pressure drop through the meter but it is so minor as to not be a problem. By example, a 5/8" meter on a 3/4" line will typically introduce a worst case 0.25psi loss at full volume of flow. I am curios as to how you connected a meter to measure the pressure at the shower head? Now for the immediate problem, how to select a shower head that will deliver more pressure? Actually what you are looking for is a shower head that will deliver more "Force", but that is another discussion entirely. Look for a shower head that has smaller diameter holes for the water to discharge, and the lower number of holes the more force you will perceive in the flow. I use a solid brass shower head that is only 1" in diameter and has about 18 holes slightly larger than a common sewing needle in diameter. It is not impressive to look at, but when you stand under this shower head it hits you like a power washer, even with low pressure. And the best part, these shower heads only cost $5 and will last a lifetime. We installed 200 of these shower heads in a motel rehab about 15 years ago and the guests were so impressed with the showers that they continually asked the desk manager where to get the shower heads. The motel manager, being an enterprising type of guy bought a dozen extras and they started selling them in the hotel gift shop for $15. The went over so great that they now sell them in the gift shop for $25, even though the real retail market price is still $5 in a hardware store.

QUOTE "I learned that as communities grow, instead of upgrading the infrastructure ($$$), cities will often resort to the easy fix which is to crank up the pressure." I find that statement extremely hard to believe because cities do not use pumps to generate the pressure. Municipal water pressure results from static head pressure developed by water towers or locating storage tanks on high elevations within the community. The municipal supplier uses pumps merely to keep the storage tank full. In fact, quite the opposite is true. In many instances the municipal line pressure increases as a result of the city replacing old lines with new lines that are larger in diameter which then results in less friction head from the source to the point of demand, ergo the pressure at the demand is higher. The municipal supplier is not required to provide PRV's. When ever a new installation is set in place the municipal supplier is required to make a tap into the municipal line and run a short section of line from the tap to the "Curb Stop" valve. The property owner is then responsible to install a code approved "Supply Line" from the curb stop to the structure, and all "Distribution Piping" within the structure. In instances where the volume will be measured by means of a meter the municipal supplier will inform the builder where the meter will ultimately be located and they five you a "Fitting allowance" measurement. You are then required to cut out a section of the supply line equal to the fitting allowance length, and in some jurisdictions the homeowner is required to install 1/2 of a meter union on each open end of the line. After the line is inspected the municipal suppliers personnel will supply and install a meter in that opening. Under both the IRC & UPC in instances where the static head pressure exceeds 80psi the homeowner is required to install a PRV (pressure reducing valve). (IRC-2903.3.1 & UPC 608.2) Under both the IRC & UPC either the valve must have an integral bypass for thermal expansion or you must install an expansion tank. (IRC 2903.4 & UPC 608.3).