PEX Replumbing

I just finished replumbing my attic with PEX. As suggested in other posts I ran all the lines first before disconnecting the existing steel pipe. Here in Houston, everything is in the attic, so it makes getting the job done in the winter almost a requirement. One thing I installed that I don't see any reference to, was a water manifold. I ordered one from Vanguard Maniblock from They carry a complete line of PEX supplies. It is basically a circuit braker for the water system (don't forget the special wrench to make the manifold connections). The cold supply line enters, another cold goes out to the Hot Wtr Htr, then returns hot. There is a hot and cold side of the manifold. The volume of the manifold helps keep constant water pressure to each fixture. You then run dedicated lines for each house fixture from the manifold. Any cold or hot line can be turned off independently on the manifold. It makes testing your finished work easy too. When I connected the new system, I could then turn on each fixture, using my trusty CSI flashlight checking all my connections for leaks. I only found one, in a shower gooseneck. All the PEX conncections were dry and tight. I set two inline brass ball valves in the 3/4 PEX. One on the supply side to isolate the manifold from the main line and one on the cold in line on the hot water heater. this way I can isolate the heater to replace it without turning off the water to the rest of the house.
I found a nice 1/2 and 3/4 crimper and cutter on Ebay for around $80. I did not replace all my steel verticals, in some cases I attached a collar and short extension to raise the pipe above rafter height to be able to get the PEX crimpers on at 90 degrees to the pipe. This is a MUST. I did run PEX down the walls to both baths where I could cut the drywall inside closets to replace fixtures and backing boards. PEX requires good backing boards and special brass fittings that the PEX attaches to by way of the standard nipple, then gives a threaded recess for a spigot pipe or shower gooseneck.
My method of installation gives me the option of later running PEX down the walls and installing directly to the sinks, toilets etc. and avoids the necessity or tearing up brickwork to replace hose bibs and other nearly inaccessible fixtures. I didn't find any corroded vertical pipes, only the horizontals lying on the rafters. I cannot begin to tell you how many pinhole were on the pipe, both 1/2 and 3/4.
An important point to remember when using PEX is the water requirements of your appliances. I found the washers and even your dish washer fillers may work on a timer based on a average flow rate, and not the actual water level. So if your pressure is low, or you undersize your PEX (I would not go below 1/2" no matter what you read or are told) your washers may be running at well below the water capacity you think they are. Low water levels are hard on your washer and your clothes for that matter.
Unfortunately, a lot of the old Texas Gulf coast homes vintage 70's and 80's(and probably newer) was built by illegals learning on the job, employed by unscrupulous developers. My attic piping was a joke. No fixtures had backing boards, the plumbing was held firm by well placed gobs of mortar. The brick work of my chimney in the attic was actually propped in place by toe-nailed 2x4's ostensibly placed to keep the brick and wet mortar in place while it set.
A good reciprocating saw, with coarse metal cutting blades is a must. It enabled me to remove pipe that would have been nearly impossible to get out otherwise.
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