PPFA User Bulletin 18
USE OF CPVC PIPING SYSTEMS WITH
This PPFA User Bulletin is designed to provide general guidance for using Chlorinated
Polyvinyl Chloride (CPVC) piping systems with residential tankless
(instantaneous) water heaters. Specific situations may and often do require
special precautions or procedures. Therefore, users should carefully assess
each specific situation before making practical application of anything
contained in this publication.
CPVC and residential tankless water
Questions have arisen about the use of chlorinated polyvinyl chloride plumbing
systems with modern domestic market household demand-type or tankless water
heaters. Under normal operating conditions and when governed by and used with adequate
safety and control devices, the performance of residential demand-type water heaters
can reasonably be expected to be within the range of performance of a properly engineered plumbing
system utilizing CPVC plumbing products.
Demand water heaters, also known as tankless or instantaneous water
heaters have been common in Europe, Asia, Central and South America for many
years. In the United States they
began appearing about 25 years ago and have recently become increasingly
popular. Unlike conventional or
storage tank type water heaters, tankless units heat the incoming water only
as needed or “on demand”. This saves the energy that would
ordinarily be lost in a traditional tank system during periods of non-use. A
tankless water heater is designed to only heat flowing water when a hot water
valve is opened in the system.
Once activated, the device delivers a constant supply of hot water. Demand water heaters come in a variety
of sizes for different applications and can be powered by natural gas,
propane or electricity.
Throughout the world safety control devices for and associated with demand-type
water heaters can vary appreciably.
The best demand water heaters have the most controlled operation
employing temperature limiting devices, pressure limiting devices and water
These water heaters employ a totally automatic operation based upon a
preset water temperature and a minimum water flow through the heater required
to activate. A demand water
heater having few inadequate, or no safety controls can pose a hazard to the occupant
and surrounding environment regardless of pipe material used downstream. On the other hand it has been
shown where these demand water heaters have proper controls and have been properly installed, these heaters can
be a safe, efficient and reliable choice.
The control and limitation of water temperature and pressure supplied to
plumbing fixtures is obviously a serious health and safety issue. Code authorities, plumbing engineers,
plumbers and users must understand the methods of protecting against both
thermal shock and scalding.
In light of these concerns many water heaters in North America are
limited to the temperature range of 122 ºF to 140ºF. This temperature is within
the specific range of CPVC materials used in plumbing applications. Temperature and pressure reducing
valves are required in North America on the hot water line near the water
heater. The standard temperature
and pressure limits for these devices are set at 210ºF and 150 psi. Regulating bodies within North America
require that CPVC plumbing materials demonstrate performance conditions of
210ºF and 150 psi for 48 hours.
This test condition represents a water heater having a high level fault in
temperature and pressure, and thus regulated by the relief T and P valve,
for two days.
CPVC pipe and fitting materials have been used in hot and cold water
plumbing systems in North America for 45 years and also have been used with
tankless devices for over 25 years in Europe. Material properties of CPVC plumbing
pipe and fittings complement the performance of these water heaters when
operating within the controlled parameters of a plumbing system. Furthermore, since the upper
temperature/pressure limits of plumbing systems are well within the
limits of CPVC pipe and fitting materials there is little chance
that CPVC pipe and fitting materials will compromise the overall system.
This PPFA User
Bulletin is designed to provide general guidance for the efficient,
effective and proper use of plastic pipe. The material contained in this Bulletin are offered solely to provide plastic pipe users
with a general frame of reference. Because specific situations can and often
do require special treatment, the material herein is not necessarly applicable to any specific situation or application. Therefore, the user should carefully assess the
requirements of his specific situation before making practical application of
anything contained in this publication.