But what’s the difference between PVC and CPVC, and which is better?
Table of Contents
What is PVC?
PVC, or polyvinyl chloride, is the third most used plastic today. It’s usually white and is solid, durable, and odorless. Currently, it’s the leading product used in home plumbing and also has extensive commercial and industrial use.
Unlike other plastics, PVC doesn’t rely upon fossil fuels or other limited resources to be produced. It has the ability to be recycled or adapted to various conditions. In addition, it’s able to be used around a variety of chemicals that might compromise other materials.
There is some concern that PVC contains as much as 57 percent chlorine and also has a high carbon and salt content that may be released if burned or left in a landfill. However, there is no solid evidence of health risks in the home at this time.
Additionally, PVC pipe replaces traditional metal pipes which can corrode and pollute your drinking water while also being less expensive to maintain.
While research into a phthalate-free version of PVC is ongoing, several other variations of this plastic have been created for more specific tasks, including CPVC. These new plastics can be used in situations where regular PVC fails.
What is CPVC?
CPVC stands for chlorinated polyvinyl chloride. While the name sounds redundant, it describes the process of increasing the chlorine content in PVC. Commercial CPVC usually has 63 to 69 percent polyvinyl chloride and a percent chlorine content, but is capable of containing as much as 74 percent.
The chlorine molecules in CPVC make it able to remain rigid in much higher temperatures, leading to its use in hot water piping, ductwork, and applications traditionally hostile to plastics. As with PVC, CPVC can be used in pipes and fittings, but may also be combined with other materials in various industrial settings.
Due to the additional processing involved, CPVC is more expensive as a material than PVC, but remains more cost-effective than traditional materials.
It has a much wider range of industrial and commercial uses than PVC. Home use tends to be mostly in HVAC applications, such drainage systems as plumbing or ventilation.
When to Use PVC or CPVC
The key difference between PVC and CPVC piping systems is in their temperature thresholds. PVC pipe is able to handle temperatures up to 140 degrees Fahrenheit before softening, whereas CPVC pipes may handle temperatures up to 200 degrees.
For this reason, CPVC is preferred (or an actual code requirement) for hot water piping where temperatures may exceed PVC safety limits. The overflow pipe that connects to the pressure relief valve is a commonly made of CPVC. PVC is still more commonly used for cold water systems and waste pipes, where it’s cheaper to use.
Another time when you should choose CPVC vs PVC is in replacing copper pipes. Both forms of PVC are available in NPS (nominal pipe size), with NPC scaled CPVC pipe usually being a dark grey or light grey color. However, CPVC also comes in CTS (copper tube size) scale, usually a light yellow color.
As the name implies, CTS scaled CPVC piping is a perfect replacement for copper piping (see also ‘Why Do Copper Pipes Turn Green And How To Clean Them?‘) and will fit into the same confines as your existing copper pipe.
A third consideration is chemical exposure. While CPVC is made from a PVC base, the two have different chemical compositions. For this reason, PVC will be more resistant to some chemicals than CPVC and vice versa.
Always consult a chemical compatibility chart before choosing between these two materials when using in a chemical application.
Can PVC and CPVC be Glued Together?
While it’s possible to combine the two materials, the ideal adhesives are different for PVC and CPVC. In addition, combining the two may compromise your system.
These two materials have different pressure and temperature ratings which could lead to leaks or other issues during use.
Types of CPVC Fittings
CPVC is not only available in a number of pipes, but also a wide range of fittings. These fittings will allow you to connect CPVC pipes in a wide range of configurations.
Reducing joints allow you to connect copper tube pipe to a different pipe size, but are not available in all types of fitting. Most reduction fittings are available with either CPVC or brass threads. Some of the more common fittings include:
- 45 degree
- 45 degree CTS
- 90 degree
- 90 degree CTS
- Reducing 90 degree
- Female elbow (90 degrees)
- Female reducing elbow (90 degrees)
- Reducing tee
- Female reducing tee
- CTS tee
- Cross tee
- Male adaptor
- Female adaptor
- CTS male adaptor
- CTS female adaptor
- Reducing male adaptor
- Reducing female adaptor
Other CPVC Connectors
- Ball valve
- CTS cap
- CTS coupler
- Reducing coupler
- End cap
- End plug, threaded
- Hex head plug
- Reducing bushing
- CTS reducing bushing
- Step over bend
- Tank connector
- CTS union
We’ve discussed the differences between Chlorinated poly vinyl chloride (CPVC) and PVC pipes, which are two of the most common types of plastic piping materials used in North America. While both PVC and CPVC pipes are made from poly vinyl chloride resin, the addition of chlorine to CPVC makes it a more durable and flexible material than PVC.
CPVC and PVC pipes are commonly used for potable water systems, vent systems.
When comparing CPVC pipe and PVC pipe, there are several key factors to consider. Some of the most important differences between the two include:
- Heat resistance: CPVC pipe can withstand higher temperatures than PVC pipe, making it a better choice for hot water supply systems.
- Pressure rating: CPVC pipe can handle higher pressures than PVC pipe, which is important for applications where high pressure is a concern.
- Chemical resistance: CPVC pipe is more resistant to chemical attacks than PVC pipe, making it a better choice for corrosive environments.
- Flexibility: CPVC pipe is more flexible than PVC pipe, which can make it easier to install in tight spaces.
- Cost: PVC pipe is generally less expensive than CPVC pipe, making it a more cost-effective choice for some applications.
In summary, both CPVC pipe and PVC pipe have their own unique advantages and disadvantages. CPVC pipe is best suited for hot water supply systems and corrosive environments, while PVC pipe is a good choice for DWV systems and cold water supply lines. When choosing between the two, it is important to consider factors such as temperature, pressure, and cost, as well as the specific needs of your plumbing application.