As a side benefit of PEX, it already has an insulating quality to it, as much as 30% better than copper. This is because copper has a fairly high emmisitivity characteristic. To reduce your losses further you may go ahead and put insulation covering on your PEX. Most often the open cell insulation that is pre-slit with joining adhesive available in 6Â lengths is used.

Although there are exceptions that prove the rule, in general all "PLUMBING" requires a permit but "Maintenance Plumbing" does not. The question then becomes, what constitutes "Plumbing" versus "Maintenance"? Maintenance is defined as maintaining an existing system in its original design and configuration therefore if you are replacing the original piping with the same size of lines and maintaining the same physical layout of the piping system you generally would not be required to pull a permit, however we must use a bit of caution here. In some jurisdictions if we are replacing pipe, valves or fixtures with exact like kind replacements it is defined as maintenance and no permit is required, but if we are switching to a different type of pipe, valves or fixtures such as replacing copper pipe with PEX they may require a permit. If we are adding additional fixtures or altering the physical location of the fixtures which would require altering the original layout of the supply and DWV lines that would technically be defined as Plumbing and generally would require both a permit and inspection. In general PEX is much easier to handle than copper but PEX requires a much greater attention to detail than copper or CPVC. By example, copper or CPVC requires a hanger within one foot of any major change in direction and one hanger for each 48" of linear run, but PEX requires a hanger for every 38" of linear run. (some jurisdictions require hangers every 36"). When installing hangers for PEX the hangers must allow fo ra greater physical movement of the pipe and the codes define a specified percentage of slack to compensate for thermal expansion and contraction, PEX must be afforded protection from both direct and indirect exposure to UV light. In some jurisdictions they require that when PEX is run through a stud bay, the underside of the stud bay must be covered with black plastic sheeting or other suitable means to prevent indirect UV light exposure. Color coding the hot and cold water lines is often done as a matter of convenience but i am not familiar with any specific code requirement to do so. Having said all of that, we must go back to what was mentioned in the previous reply. All jurisdictions have differing rules on permits. By example, in our municipal jurisdiction we are required to pull a permit for all water heater installations whether it is new or a replacement. On the other hand, in the county outside of our municipal district you can build an entire house from the foundation to finish and the only permits required are to drill a well, install a septic tank or attach the driveway to the public roadway.

You could order a C X 1' MPT adapter. That would fit over the 1" pipe. You could buy a 1" fitting by mph adapter and that would go inside the 1'CU coupling you want. If you need 6" of copper just stop by a plumbing shop and ask for a stub of pipe for a project you have. They may give it to you. Worth a try;)

My house is 1260 square feet on two floors, with another 630 square feet in the basement. There are four radiators for each floor, and a gas-fired boiler in the basement. The basement has no radiators, but I have three manifold ports open for future expansion. I ran Everhot oxygen barrier PEX, but left the iron pipe sections running down to the basement and put PEX adapters on the end of each down-pipe. From there I ran the PEX to a manifold like one of these https://www.pexuniverse.com/radiant-heat-manifolds.  The manifold has individual flow meters and a balancing valve for each line. IIRC you can also buy an electrically operated balancing valve that could be turned on and off to zone the system. I put the two manifolds near the boiler, which was in one corner of the house. That meant some fairly long PEX runs to get to the other corner of the house. I also had to dip the PEX runs down low enough to get under the steel beam in the basement, so they are a bit curvy in that area. However, it went in with no problems. I can go to the PEX manifolds in the basement and see the input and return water temps for each manifold. I can also see the flow rate of the water running to each radiator. One surprise for the balancing valves is that they do not completely close off the flow, so you can't use them to completely shut off water to a radiator. That would have been convenient if I have to do work on one radiator. I had to install caps on the unused ports to completely cut off the flow. FYI - I installed the manifolds (referenced in my link above) upside down because all my radiators were above the manifold and that made the routing easier. It all works fine that way, except the labels and temp gauges are upside down. Bruce