Plumbers use PEX piping as it's easy to work with, requires no glue or set time, is flexible and can maneuver around corners easily without the need for additional fittings and elbows and it's also very durable.
PEX pipe is safe and approved for hot water for both commercial and residential hot and cold water systems.
PEX pipe is also safe and approved for municipal water service lines, hydronic baseboard heating systems, radiant panel heating system, building service pipes and snow and ice melting systems.
PEX is better than PVC as it works great for both hot and cold water and it's also easier to work with and you can install it with less fittings than you could with PVC because PEX is pretty flexible.
PEX holds up better to frozen water than PVC does as well which means it's less likely to burst when you have frozen water pipes.
You do however need to use a PEX crimp ring tool though and ensure the crimp rings are tight enough so that the PEX does not leak.
PVC pipe begins to melt at temperatures of above 140 F.
The type of pipe that is not suitable for hot water supplies is PVC pipe as it can release chemicals into the water when heated and because PVC cannot withstand hot water temperatures very well.
The type of pipe that is used for hot water is either CPVC, PEX, copper pipe or even galvanized piping.
PVC pipe can take heat up to 140 F before it will begin to melt and break down chemically.
If you use PVC on hot water it will be okay as long as the water temperature is 140 F or less.
If you use PVC on hot water above 140 F then the PVC can start to melt and break down chemically.
For water temperatures above 140 F you want to use CPVC or PEX which can withstand higher temperatures than PVC.
You can use regular PVC for hot water line up to 140 F degrees.
Regular PVC can withstand water temperatures up to 140 F which is okay for residential water lines as hot water temperatures for residential settings should not get over 140 F.
The kind of plastic pipes that you should use for hot water is CPVC or PEX Pipe.
If using PVC for cold water then you should use CPVC pipe for hot water as it's made to hold up to water temperatures of 200 F.
CPVC is better than PVC for hot water as PVC can only handle hot water temperatures up to 140 F and CPVC pipe can handle hot water temperatures up to 200 F.
CPVC pipe is good for hot water as CPVC pipe can handle hot water temperatures up to 200 F and it can also be used for cold water as well.
CPVC pipe can be used for supplying both cold and hot water in plumbing systems as CPVC is made to hold up to both hot water and cold water and PVC is meant to only handle cold water but PVC can handle water temperatures up to 140 F.
You can also use PEX or Copper piping for hot and cold supply lines in plumbing systems.
You can use schedule 40 PVC pipe for drinking water but it should not be used for hot water as it could melt but for cold water PVC pipe is okay and okay for drinking water.
You should not use PVC pipe on water lines that exceed water temperatures above 140 F as it can become toxic and could melt and leak.
PVC has a melting point of 180 F and the higher the temperature the faster it begins to melt.
The melting point on some grades and types of PVC can be as high as 500 F but most PVC begins to melt at 180 F.
PVC pipe does become toxic when heated as it has been found that when heated the PVC releases toxic hydrogen chloride gas.
PVC pipe can be used on hot water lines as long as the hot water does not reach higher than 140 F.
The primer on PVC pipes cleans the pipes and makes it easier for the PVC pipes to bond together as it also softens the plastic of the PVC pipes.
Plumbers use purple primer on PVC as it cleans the pipes and fittings of dirt, oil, grease or other foreign matter that can make it difficult for the PVC cement to bond the fitting and pipe together.
The Purple primer when used on PVC pipe also softens the plastic of the pipe so that it bonds together easier as well.
Before turning on the water you should allow the PVC glue to dry and cure for at least 2 hours.
It takes at least 15 minutes for the PVC glue to get a good bond with the pipe and fittings but for full strength it takes up to 2 hours.
So you should always wait until 2 hours have passed before you pressurize the water system and turn the water on because turning the water on too soon could cause the pipes and fittings to come apart.
The PVC glue melts the pipe and fittings together through a chemical reaction.
It does not glue the pipe like normal glue but instead melts the pipes together to form the bond and it can take 2 hours for the reaction to fully work and create a good permanent strong bond.
Also when putting the pipe and fittings together make sure to twist the pipes and fittings back and forth and hold them together for about a minute.
Holding the pipe and fittings together helps keep the pipes and fittings from pushing apart.