Onix Fact Sheet - JupiterHeating.com

get
Onix
Getting Started
As the radiant industry grows and new
products become available, one question continues to surface: What tubing
do I use?
The best answer to this question is
this: choose the right tool for the job.
Is Onix right for every job? Or should
PEX be used?
The following charts illustrate a typical frame floor application, using both
UnderFloor and Thin Slab approaches.
The values listed are Watts Radiant
list prices. Actual costs may vary
from area to area
What do these
charts show?
Basically, Onix Staple-Up™ can deliver
the necessary heat load, comfort level
and installation requirements at a
much lower price than any other
underfloor installation technique.
Misconceptions:
One misconception with a frame floor
application is that a frame floor, or
underfloor application, cannot deliver
the same amount of heat as a Thin
Slab or Slab-on-Grade.
and get going
Fact:
Heat output from a
radiant floor is
limited by the
floor covering,
fluid supply temperature and the
allowable floor
surface temperature. On average,
the maximum
floor surface temperature allowed is
85°F, which corresponds to about 45
BTU/sqf. This is
true regardless of
the floor construction.
The only exception to this is with
a suspended installation. Since there is no direct contact
with the tubing and the subfloor, the
maximum heating output from a
Suspended floor is limited to around
25 BTU/sqf. This limitation should be
noted in the design process, if the system is a floor warming application or
in a low heat demand environment.
Misconceptions:
Thin Slabs and PEX plates enhance
the floors ability to heat a room when
compared to a Onix Staple-Up.
Fact:
Thin Slabs and plates may allow a
lower required supply fluid temperature, but no not increase the floors
ability to emit heat. The floor’s ability
to transfer heat to a space is limited by
the floor covering material. More
conductive floor coverings, with a
high emissive value will emit heat easier and faster than a more insulative
floor covering.
EPDM Outer Cover
Aramid Reinforcement
EDPM Boding Layer
AlumaShield
EPDM Inner Tube
3131 W. Chestnut Expressway
Springfield, MO 65802
ph: 417.864.6108 800.276.2419
fax: 417.864.8161
web: www.wattsradiant.com
3131 W. Chestnut Expressway
Springfield, MO 65802
ph: 417.864.6108 800.276.2419
fax: 417.864.8161
web: www.wattsradiant.com
Onix: Staple-Up ™
200 ft Circuits
M-5 Manifolds
8” oc Spacing
Comparision Details
House Size: . . . . . . . . . . . . . . . . . 2,400 sqf
No. of Zones: . . . . . . . . . . . . . . . 4
Average Zone Size: . . . . . . . . . . . 600 sqf
System options, accessories and dealer discounts
may alter actual system costs.
All prices shown are list prices.
Onix Staple Up ™
Item
Number of Units
3/8" Onix
4000
Staples
8000
Angle Drill (rental)
1
Splice Kit
1
Unwinder
1
Manifold - BVR
4
SelfTite Clamps
4
Staple Gun (rental)
1
Labor*
20
Insulation**
2400
Cost per Unit
$1.55
$0.018
$50.00
$20.00
$70.39
$249.50
$12.41
$50.00
$100.00
$1.00
*Labor cost is based on $100/hr; 200ft/hr
**Insulation cost is the same for all frame floor comparisons
- value estimated to include insulation and
installation labor
Total
$6,200.00
$140.00
$50.00
$20.00
$70.39
$998.00
$49.64
$50.00
$2,000.00
$2,400.00
PEX Underfloor: Plates; Crimp Fittings
*Labor cost is based on $100/hr; 100ft/hr
**Insulation cost is the same for all frame floor comparisons
- value estimated to include insulation and
installation labor.
PEX Thin Slab: Crimp Fittings
$11,978.03
$4.99 per sq. ft.
(List Price)
*Labor is figured based on $100/hr; 100ft/hr
**Insulation cost is the same for all frame floor comparisons
- value estimated to include insulation and
installation labor.
***Cost excludes double framing of wall and increased
structural costs 1.5" of thinslab - cost may vary.
PEX Underfloor: Plates: Crimp Fittings
PEX Thin Slab: Crimp Fittings
300 ft Circuits
M-4 Manifolds
8” oc Spacing
330 ft Circuits
M-2 Manifolds
12” oc Spacing
Item
Number of Units
1/2" Pex
4000
Plates
1600
Nails/Screws
1
Silicone
1
Angle Drill (Rental)
1
Splice Kit
1
Manifolds - BVR
4
Crimp Rings (100ct)
1
Crimp Tool
1
Unwinder
1
Labor*
40
Insulation**
2400
Cost per Unit
$0.75
$3.30
$20.00
$40.00
$50.00
$2.85
$200.40
$21.00
$260.00
$464.89
$100.00
$1.00
Total
$3,000.00
$5,280.00
$20.00
$40.00
$50.00
$2.85
$801.60
$21.00
$260.00
$464.89
$4,000.00
$2,400.00
$16,340.34
$6.81 per sq.ft.
(List Price)
Item
Number of Units
1/2" Pex
3000
Staple Gun (rented)
1
Staples
3
ThinSlab Material***
2400
Splice Kit
1
Manifolds - BVR
3
Crimp Rings (100ct)
1
Crimp Tool
1
Unwinder
1
Labor*
15
Insulation**
2400
Cost per Unit
$0.75
$50.00
$17.50
$4.00
$2.85
$200.40
$21.00
$260.00
$464.89
$100.00
$1.00
Total
$2,250.00
$50.00
$52.50
$9,600.00
$2.85
$601.20
$21.00
$260.00
$464.89
$1,500.00
$2,400.00
$17,202.44
$7.17 per sq. ft.
(List Price)
FACT
D&
ATA
SHEET
presented by
ONIX™:
Not All Radiant Tubing Is The Same
Onix is a flexible tubing specifically
engineered and manufactured for use in
radiant floors or as hydronic supply and
return tubing.
EPDM Outer Cover
AlumaShield™ Oxygen Barrier
EPDM Inner Tubing
The unique chemical composition and
manufacturing process of Onix make it
the perfect choice for use as long-lasting,
high-temperature hydronic tubing.
Most people are familiar with the many
different types of plastic (PEX, polyethylene, CPVC, and ABS to name a few) and
their different characteristics and applications. Just as different plastics have different material properties, so do different
types of rubber (EPDM, SBR, NBR or
nitrile, Neoprene, natural rubber).
Question:
What is Onix?
Answer:
Onix is a polymer-rich EPDM; comprising a five layer, synthetic, flexible tube.
The inner fluid channel is a peroxide
cross-linked, high-grade EPDM. The
inner tube is wrapped with a flexible 00
grade aluminum oxygen barrier. Next is
a peroxide cross-linked middle layer of
EPDM, wrapped by spiral cords of
aramid reinforcing. The cover is a sulphur cross-linked EPDM.
Fluid Channel
nt
ia
WattsRad
Onix™ by
EPDM Bonding Layer
Aramid Fiber Reinforcing
Question:
What is EPDM and why was it
chosen for this application?
makeup, EPDM is an extremely stable
polymer for high temperature applications.
Answer:
Question:
What is vulcanization?
EPDM (Ethylene Propylene Diene
Monomer) is a flexible cross-linked molecule. The repeating unit is ethylene,
propylene, and a diene, which contains a
double bond for crosslinking. The diene
is ENB (norbornene).
There are many different grades of
EPDM. Unlike other grades of EPDM,
the EPDM used in Onix is a high quality,
polymer-rich formulation, utilizing relatively high ethylene grades with high
molecular weights.
EPDM was chosen because it has a
proven track record at high temperature
applications. EPDM has been used in
applications such as steam hose since
World War II. Because of its molecular
Answer:
Vulcanization is the process that crosslinks the rubber molecules to form a
stronger, more durable molecule.
Vulcanization involves immersing the
rubber in a steam bath where the energy
from the steam and a peroxide catalyst
cross-link the rubber molecules into
longer polymer chains.
Peroxide vulcanization uses peroxide as a
catalyst in the crosslinking process of
EPDM. The peroxide is scavenged in the
ONIX TESTING
Watts Radiant has been involved in the hydronic radiant floor industry since 1980.
Third party testing results “place this
material [Onix] among the most stable
materials we have reviewed.” In addition “this compound is among the best
that we have tested.”
Watts Radiant is a wholly-owned subsidiary of Watts Industries. Since 1874, Watts
Industries has been a leading world-wide manufacturer of valves, hydronic heating,
and plumbing equipment. Watts is currently traded on the NYSE as WTS.
Samples of Onix have been running at
180ºF on test panels for over 60,000
hours – CONTINUOUSLY.
Who Is Watts Radiant?
Watts Radiant Literature, July 1, 2003 – Not All Radiant Tubing Is The Same
©Watts Radiant 2003
page 1
FACT
D&
ATA
SHEET
Ethylene
presented by
X
Y
Propylene
Cross Linking Site
A peroxide catalyst breaks the double bond
to form C–C (Carbon to Carbon) single
bond with the next EPDM molecule, forming a strong, large, three dimensional
chain of molecules.
Diene
(ENB)
process, leaving a single carbon-carbon
(C-C) bond.
Cross-linking forms a three dimensional
molecular network that makes EPDM
extremely stable over a wide range of
temperatures and pressures.
Question:
What is aramid fiber reinforcing?
Answer:
Aramid is used as a reinforcement to
resist pressure. It gives Onix a 800 psi
burst pressure at ambient and a 600 psi
burst pressure at 180ºF (compared to 325
psi burst at 180ºF of Pex).
Aramid offers the best heat resistance
over time of any reinforcing. Pound for
pound aramid is stronger than steel.
Aramid is used in bulletproof vests under
the trade name Kevlar .
Question:
How is Onix manufactured?
Answer:
Onix is made in a continuous, five-stage
process, using three extruders, an aluminum applicator, and an aramid braider.
It is then cross-linked in a 325ºF steam
bath.
– Raw materials are mixed together, then
held until passing Quality Control tests.
– Inner tube is extruded through a die in
a screw extruder while being checked
by a laser micrometer. Nitrogen gas is
used to expand the tube wall and maintain a consistent inside diameter.
– Aluminum oxygen barrier is applied.
– Bonding layer of EPDM is extruded.
– Spiral aramid reinforcement is
wrapped.
Watts Radiant Literature, July 1, 2003 – Not All Radiant Tubing Is The Same
Z
– Outer cover is extruded.
– Entire Onix assembly is vulcanized in a
low-pressure steam bath at 325ºF.
Vulcanizing in a pan limits the longest
continuous length but is a more consistent/higher quality cure process than a
continuous cure process.
Question:
Chemical Facts
EPDM is cross-linked with carbon-carbon single bonds.
It takes more imparted energy from
oxygen, sunlight, chlorine, or other
damaging agents to break a single
bond than a double bond. This is
because the double bond has a free
“leg” available to reconnect to a new
molecule. The result is a very stable
long lived material.
©Watts Radiant 2003
page 2
FACT
D&
ATA
SHEET
Why is there only one manufacturer of EPDM tubing for radiant
heating?
Answer:
Watts Radiant holds the patent for radiant
floor applications using EPDM with an
oxygen barrier.
There are only a handful of polymer manufacturers who have the capacity and volume to produce EPDM tubing.
Manufacturing multi-layer EPDM tubing
requires a very large capital investment,
up to eight times greater than required to
extrude plastic. This investment results
in a product with only one application radiant.
presented by
samples are pressure tested. Pressures
include proof (400 psig) and burst testing.
– A Rheometer test is performed on each
batch of compound (tests crosslinking
over time by measuring torque).
– Tensile, elongation, specific gravity,
viscosity, and moony scorch testing is
done on designated batches.
– Tensile and elongation at break is
measured for each lot of the aramid
reinforcing yarn.
Question:
What is the difference between
Question:
How is Onix tested?
Onix has been tested by independent third
party labs. Components used in the construction of Onix have been subjected to
accelerated lifetime prediction tests, such
as differential scanning calorimetry
(DSC), and thermogravimetric weight
analysis (TGA). The DSC testing studies the oxidation process of the polymer.
The TGA test studies weight loss.
Product I.D. O.D.
3/8”
1/2”
5/8”
3/4”
1”
Quality Control Testing:
– As part of each shift's production, hose
The base polymer for Onix is a highgrade EPDM. The base polymer for
heater hose is SBR (Styrene-butadiene
rubber). Other material used as radiant
hose has been NBR (nitrile-butadiene
rubber)
– EPDM is inherently stable at high temperatures, and is not dependent on the
anti-oxidant package for protection. An
EPDM is like using a stainless steel
roof - it is inherently corrosion resistant.
– All extruded and cured pipes (PEX or
CPVC, for example) use an anti-oxidant package to extend protection
3/8”
1/2”
5/8”
3/4”
1”
11/16”
7/8”
1”
1-1/8”
1-3/8”
Bend Fluid Capacity
Radius
per 1000 ft.
3”
4”
5”
6”
8”
6.25 gal.
10.25 gal.
16.00 gal.
25.00 gal.
43.50 gal.
General Properties of EPDM
Abrasion Resistance . . . . . . . . . . . . . . . . .Excellent
Oxidation (resistance of) . . . . . . . . . . . . . .Excellent
Ozone (resistance of) . . . . . . . . . . . . . . . .Excellent
Sunlight Aging . . . . . . . . . . . . . . . . . . . . .Excellent
Heat Aging . . . . . . . . . . . . . . . . . . . . . . . .Excellent
– Third party testing results “place this
material [Onix] among the most stable
materials we have reviewed.” In addition “this compound is among the best
that we have tested.”
– Samples of Onix have been running at
180°F on test panels for over 60,000
hours CONTINUOUSLY.
Answer:
ONIX Product Dimensions
Answer:
Representative samples are periodically
placed on Watts Radiant's long term testing panels, where they undergo continuous exposure at elevated temperatures to
both water and water/glycol mixes.
Onix and flexible tubing like automotive heater hose or other radiant hose?
ONIX: Table of Material Properties
Tensile Strength . . . . . . . . . . . . . . . . . . . .1000 psi
Percent Elongation . . . . . . . . . . . . . . . . . .300 %
Low Temp Flexibility . . . . . . . . . . . . . . . .10 times ID @ -40ºF
Ozone resistance . . . . . . . . . . . . . . . . . . . .100 pphm, 50% extension, no cracks
Electrical resistance . . . . . . . . . . . . . . . . . Greater than 10 mega ohms
Burst pressures
at ambient . . . . . . . . . . . . . . . . . . . . . .800 psi at 73ºF
at 180ºF . . . . . . . . . . . . . . . . . . . . . . . .600 psi at 180ºF
Thermal conductivity . . . . . . . . . . . . . . . .0.17 Btu/hr-ft-Deg F
Watts Radiant Literature, July 1, 2003 – Not All Radiant Tubing Is The Same
©Watts Radiant 2003
page 3
FACT
D&
ATA
SHEET
against premature "aging" of the pipe.
Other rubber materials such as
SBR/NBR is extremely sensitive to
having the correct anti-oxidant package. Anti-oxidants retard thermal
oxidative hardening by capturing radicals and preventing the chemical reaction from propagating. This is similar
to using a plain steel roof (NBR or
SBR) - you have to paint it (add an
exact amount of anti-oxidants) to keep
it from rusting.
At the molecular level, the major difference between NBR (or SBR, or neoprene) and EPDM is that NBR contains
carbon-carbon double bonds while
EPDM contains very stable carboncarbon single bonds.
– Double bonds are very reactive and are
presented by
"unsaturated." This means that the carbon-carbon double bonds of the NBR
are much more likely to be oxidized
(age) than the "saturated" carbon-carbon single bonds of EPDM, thus making EPDM a much more stable molecule at high temperatures.
ONIX Staple-Up™
– Single bonds require more energy to
break than double bonds.
Because of Onix’s inherent benefits for
Radiant Floor Heating pipe and Supply
and Return Piping—its flexibility,
longevity and durability (see table)—it is
the best material to use in your next
Underfloor, Slab, or snowmelting application.
Why should I install Onix?
ONIX Slab–On–Grade
ONIX Snowmelt
Long lasting . . . . . . . . . . . . . .Backed by a comprehensive 25 year warranty
Most flexible, durable
radiant tube available . . . . . .Installs in less time than any other radiant tube
Flexible to -30ºF . . . . . . . . . . .Easy installations in freezing cold weather
Can't be kinked . . . . . . . . . . .Double it up and push it through a hole in a joist for
faster Staple–Up™ installations
UV resistant . . . . . . . . . . . . . .Up to 5 years. Leave it exposed on a
job-site, worry-free
ONIX with SubRay™
No special tools required . . . .No expensive connection tool or tube unwinder
Crush resistant . . . . . . . . . . . .Large concrete pours are possible – let the concrete
truck roll over Onix (see Onix Installation Manual)
Aluminum oxygen barrier . .Flexible oxygen barrier is protected inside the tubing
– Can't damage it on the jobsite
– Aluminum oxygen barrier is unaffected by temperature (just as effective at 180°F as 100°F, unlike other
oxygen barriers on the market)
No expansion . . . . . . . . . . . . .No movement when Onix heats up
– Never noisy in a Staple–Up application; stays in contact with subfloor for better heat transfer
Watts Radiant Literature, July 1, 2003 – Not All Radiant Tubing Is The Same
3131 W. Chestnut Expressway
Springfield, MO 65802
ph: 417.864.6108
fax: 417.864.8161
www.wattsradiant.com
©Watts Radiant 2003
page 4
SHEET
FACT
D&
ATA
presented by
Staple–Up™ With Onix
There seems to be a lot of misinformation regarding performance and efficiency of Staple-Up™ systems. Despite the
fact that Watts Radiant has experience
with tens-of-thousands of Staple-Up
systems over the last 22 years in some
of the coldest climates in the country,
some insist that Staple-Up "doesn't
work" or it has "limited heat capacity"
or it is "much more expensive to operate."
The goal of this technical piece is to put
these myths to rest and help explain the
advantages of Staple-Up systems.
Question:
Is it true an Onix Staple-Up application
costs less than PEX, even though the
Onix tubing costs more?
Question:
Answer:
Yes, Onix Staple-Up applications do
cost less than PEX Underfloor applications. There are two main reasons. The
first has to do with labor. Onix installs
2-3 times faster than PEX. This is due
in part to the increased flexibility of
Onix over PEX, not to mention the
additional time needed to install the special fasteners required for PEX, such as
clips and/or heat transfer plates.
These additional fasteners also increase
the cost of a PEX system. Even though
Onix tubing may cost
more than PEX tubing, the cost of Onix
with staples is about
40% less than PEX
with metal plates (see
table).
Why can't PEX be stapled directly to the
underside of the subfloor like Onix?
Answer:
PEX will expand and contract as it is
heated and cooled. How much it will
move is directly proportional to the
change in temperature. PEX tubing
expands 1.1 inch for every 10 degree
rise in temperature for every 100 feet of
tubing. If a 200 ft. circuit of PEX is
Onix Staple-Up
Tubing Cost
$2.55
Staples/Screws
$0.02
Metal Plates
SubRay
Light Crete
Structural
Modifications
TOTALS
$2.57/sf
PEX w/Plates
$1.24
$0.50
$4.00
filled with 60°F water and heated to
160°F, the PEX expands approximately
22 inches.
This movement can cause noise and
wear, either against the floor or against
the staples themselves. A considerable
amount of noise can be generated as the
PEX expands and rubs against the metal
plates or staples. This noise is transmitted into the house. Also, there is a question of heat transfer. As the PEX
expands it has a tendency to pull away
PEX Sandwich
$1.24
$0.08
PEX Thinslab
$0.85
$4.65
$4.00
$1.50
$5.74/sf
$5.97/sf
$6.35/sf
Values shown are based on a list price per square foot basis. Cost considerations are for tubing and attachment materials only.
Labor costs are in addition to the totals listed above.
WattsRadiant Literature, May 1, 2003
©WattsRadiant 2003
page 1
SHEET
FACT
D&
ATA
Phase 1: Initial Start-up Conditions
from the subfloor. This
separation decreases
the tubing's ability to
transfer energy to the
subfloor, and reduces
its overall heating ability.
Conductive Energy Transfer
Onix stapled directly to subfloor.
Radiant
Energy Transfer
Foil Faced Insulation
Question:
Why doesn't Onix have
these problems?
Answer:
Phase 2: Mid-Point Conditions
Onix is comprised of a
cross-linked EPDM
compound that does
not expand with temperature changes. Onix
is the same diameter
and length at 200°F as
it is at 50°F.
Phase 3: Steady-State Conditions
80°F
77°F
80°F
Air tight cavity is important to help maintain a constant,
uniform air temperature in the joist cavity.
77°F
No expansion means
no wear on the tubing,
no noise and no
reduced heat transfer
due to tubing moving
away from the floor.
Question:
I've heard Staple-Up applications cause
thermal striping. Is this true?
Answer:
No. Onix Staple-Up does not cause thermal striping (objectable temperature differences). All radiant floor applications
will experience some thermal variances
in floor surface temperature on start up.
This is due to the instantaneous load on
the floor at that time. As the floor reaches steady-state conditions, this variance
evens out, resulting in a very even floor
temperature.
The surface temperature for an Onix
Staple-Up system will be nearly identical to that of a PEX underfloor system
with plates.
Most ThinSlab applications will experience a greater sense of thermal striping
on start up than a Staple-Up application.
This is because the increased conductivity of the thin concrete above the tubing
sends the heat to the surface faster than
the mid-point between the circuits. This
results in a greater initial striping.
Tube spacing has a direct impact on
how much temperature difference a
floor can experience. The wider the tube
spacing the greater the potential for
striping. Staple-Up applications are 8"
on center while Thin Slab applications
are usually 12" on center.
The two images on to the left show a the temperature of a floor in
a standard forced air heated home. The image to the right shows
a radiant tile floor.
Notice the color of the radiant floor and the person’s hand. Both
are about the same color, indicating both are about the same temperature. The person in this room is losing very little energy to
the floor and is much more comfortable as a result.
WattsRadiant Literature, May 1, 2003
©WattsRadiant 2003
page 2
SHEET
FACT
D&
ATA
Once all properly installed radiant systems reach steady-state conditions, temperature differences are insignificant,
resulting in a very even floor temperature.
Question:
I've been told heat transfer plates are
required to spread the heat out across
the floor. Why doesn't Onix need heat
transfer plates?
Answer:
Onix does not need heat transfer plates
for two reasons. First, Onix is in direct
contact with the subfloor, resulting in
direct conductive, efficient heat transfer.
Second, Watts Radiant recommends all
Onix Staple-Up installations use foilfaced insulation. The foil on the insulation "reflects" the downward energy
back up into the subfloor. This reflected
energy is spread out over the bottom of
the subfloor, creating an even temperature.
Onix Staple-Up Nomograph showing a supply temperature of 125° with a BTU load of 25 BTU/sqft and
floor surface temperature of 81°F.
Question:
Does Onix Staple-Up take longer to
respond than other frame floor applications?
Answer:
No. Response times are dictated by the
thermal mass of the construction material, not the radiant tubing. All construction materials have a Specific Heat
Value; this is the amount of energy
required to raise the temperature of one
pound of material one degree
Fahrenheit.
The tables reflect the requirements for a
1,000 sf. room with a floor temperature
change from 50°F to 80°F with a 50,000
Btu/hr output boiler. These numbers
only reflect the time and load required
to change the floor mass temperature,
and do not take into account the additional load required to raise the room
temperature, or to sustain the room's
heat load.
WattsRadiant Literature, May 1, 2003
PEX with Plates Nomograph showing a supply temperature of 120° with a BTU load of 25 BTU/sqft and
floor surface temperature of 81°F.
©WattsRadiant 2003
page 3
SHEET
FACT
D&
ATA
Question:
HiGuard™ Industrial Cover
Why don't hanging PEX applications
work as well as Onix Staple-Up?
AlumaShield™ Oxygen Barrier
Answer:
Hanging PEX applications suspend the
tubing in the joist cavity with a series of
plastic clips spaced every 24 - 32" on
center. This is done to eliminate the
noise as the PEX tubing expands and
contracts with temperature changes.
This creates an air gap between the
PEX tubing and the subfloor, eliminating conductive heat transfer from the
tubing. A major result of this lack of
contact is a reduction in the total BTUs
produced. Most hanging PEX applications are limited to a maximum of 20
BTU/hr per square foot, often requiring
the installation of supplemental heat.
Time Required to Heat Floor
4” Concrete
5.88 Hours
1.5” Thin Slab
1.93 Hours
0.75” Subfloor
0.66 Hours
Heat Capacities
4” Concrete
9.80 BTU/ft3°F
1.5” Thin Slab
3.22 BTU/ft3°F
0.75” Subfloor (Staple-Up) 1.10 BTU/ft3°F
BTU’s Required
4” Concrete
294 MBH
1.5” Thin Slab
96.6 MBH
0.75” Subfloor (Staple-Up) 33.0 MBH
Onix Staple-Up applications can produce up to 45 BTU/hr/sq. ft. of useable
heat. This is a result of the Onix having
direct contact with the subfloor.
nt
atts Radia
W
y
b
™
ix
On
Durel™ Inner Tubing
Fluid Channel
Contour Extrusion Layer
Aramid™ Fiber Reinforcing
Question:
Why does Onix require a higher supply
water temperature than PEX when both
are installed the same way?
On the average, when compared to
PEX, Onix will only see around a 5-8°F
variance on supply fluid temperatures.
Answer:
Question:
Onix requires a slightly higher water
temperature because of the physical
properties of the material. Onix is composed of EPDM rubber with a thicker
wall profile (added resistance to jobsite
abuse) than a PEX tubing.
Answer:
Due to the thicker wall, a slightly higher
water temperature is required to achieve
the same outside tubing temperature as
would be seen with PEX. Since both
pipe outer surface temperatures are the
same, then they both have the same
BTU delivery to the floor and same
overall system response.
The average supply fluid temperature difference
between Onix and PEX is approximately 8°F.
tw = supply fluid temperature
td = outside tube surface temperature
Doesn't a higher supply temperature
mean higher operating costs?
No. Operating costs are determined
solely by the amount of energy consumed (BTUs), not by the supply water
temperature.
One easy way to monitor energy usage
is to measure flow rate (gpm) and system temperature drop (supply water
temp - return water temp). At a flow
rate of one gallon of pure water per
minute, a temperature drop of 20°F will
"deliver" 10,000 BTU/hr. Whether the
Fluid Temperature Variances
Temperature Drop
Tubing Material
(tw - td) °F
1/2" EPDM Rubber
13.098
1/2" PEX-AL-PEX
4.418
1/2" PEX
4.848
1/2" L Copper
practically 0°F
Various Piping Thermal Properties
Tubing Material
1/2" EPDM
1/2" PEX-AL-PEX
1/2" PEX
1/2" L Copper
Inside Diameter
(inch)
0.5
0.472
0.472
0.545
WattsRadiant Literature, May 1, 2003
Outside Diameter
(inch)
0.875
0.63
0.63
0.625
Thermal Conductance
(Btu/hr.*ft.*°F)
0.17
0.26
0.237
223
Thermal Resistance
(hr.*ft.*°F/Btu)
0.5239
0.1767
0.1939
0.9775 x 10-4
©WattsRadiant 2003
page 4
SHEET
FACT
D&
ATA
temperature drop is from 150°F to
130°F or 110°F to 90°F, one gpm will
always "deliver" 10,000 BTU/hr.
Btu/hr = GPM x 500 x DT
GPM = system flow rate in
gallons per minute
DT = Supply water temperature return water temperature
Most radiant systems operate with a
non-condensing boiler, meaning the
boiler needs to operate at 140°F to
160°F (supply) or above. So, whether a
radiant system operates at 150°F or
110°F, the boiler water is "mixed down"
to supply the radiant system. This
means the flue and stack losses from the
boiler will be the same for both radiant
supply temperatures.
Remembering that the energy consumed
(BTU/hr.) is determined by flow rate
and temperature DROP (not supply temperature), a radiant system that requires
150°F supply will not use more energy
that a system that requires 110°F.
The only time a lower water temperature translates to better efficiency is if a
condensing boiler is used. These boilers
are designed to operate at very low
return temperatures, such as a
snowmelting application.
Question:
What material is Onix made from?
How is it different from other rubbers
like automotive radiator hose or other
radiant hose materials?
Onix Bend Radius
R4"
R3"
R3"
6"
4"
WattsRadiant Literature, May 1, 2003
8"
Onix (EPDM) Properties
Tensile Strength . . . . . . . . . . . . . . . . . . . .1000 psi
Percent Elongation . . . . . . . . . . . . . . . . . .300 %
Low Temp Flexibility . . . . . . . . . . . . . . . .10 times ID @ -40 Deg F
Ozone resistance . . . . . . . . . . . . . . . . . . . .100 pphm, 50% extension, no cracks
Electrical resistance . . . . . . . . . . . . . . . . . Greater than 10 mega ohms
Burst pressures
at ambient . . . . . . . . . . . . . . . . . . . . . .800 psi at 73 Deg F
at 180 Deg F . . . . . . . . . . . . . . . . . . . .600 psi at 180 Deg F
Thermal conductivity . . . . . . . . . . . . . . . .0.17 Btu/hr-ft-Deg F
Answer:
Onix is a multi-layer composite product,
with EPDM, aramid reinforcing and a
ductile aluminum oxygen barrier.
EPDM stands for Ethylene Propylene
Diene Monomer, which is a cross-linked
synthetic rubber. The peroxide-cured
carbon-carbon bonds that form the
cross-linking in the Onix tubing are
extremely stable and give Onix the ability to resist sunlight, oxidative aging,
and and long term effects of high temperature operation.
Besides being operated for over 60,000
continuous hours of testing at 180°F,
Watts Radiant sends samples of Onix to
independent labs for further testing.
These labs test the components used in
the construction of Onix tubing.
These tests determine the physical and
chemical changes the compenents
undergo. Based on the variances from
beginning to end, an estimated life span
is determined.
-
Question:
What testing has taken place to ensure
Onix will last?
Answer:
Question:
Watts Radiant continuously tests Onix
in multiple phases of production. Each
batch of tubing produced is tested to a
min. 100 psig pressure to ensure burst
resistance. A Rheometer test is also performed on each batch, which tests the
cross-linking. During production other
material properties are tested, such as
tensile strength, elongation, specific
gravity, and viscosity levels.
How does Onix compare to PEX?
I.D.
Onix Bend
PEX Bend
Radius
Radius
Size
3/8” . . . . . . .3” . . . . . . . . . . . .4
1/2” . . . . . . .4” . . . . . . . . . . . .5”
5/8” . . . . . . .5” . . . . . . . . . . . .6”
3/4” . . . . . . .6” . . . . . . . . . . . .7”
1” . . . . . . . .8” . . . . . . . . . . .10”
PEX Bend Radius
Answer:
Onix outperforms PEX on several levels.
1.Onix has a tighter bend radius than
an equivalent PEX size, making
installation easier. Onix can be
installed in tighter areas, allowing
for more effective coverage.
R4"
R3"
R3"
6"
8"
4"
©WattsRadiant 2003
page 5
SHEET
FACT
D&
ATA
2.Onix cannot be permanently
kinked, eliminating wasted jobsite
time spent repairing kinks in PEX
tubing.
3.Onix is UV resistant for a minimum
of 5 years, so it can be left in the
sun on the jobsite without damaging the tubing or the oxygen barrier.
4.Onix remains flexible to sub-zero
temperatures, making it easy to
install in frigid environments.
5.Onix has a burst rating of 600 psig
at 180°F, while PEX has a burst
rating of 325psig at 180°F, meaning
it will hold up to extreme "runaway" boiler conditions.
6.Onix does not require special tools
to make the connection at the manifold, saving hundreds of dollars in
tool costs.
7.Onix's oxygen barrier is inside the
tubing, protecting it from job site
abuse.
8.Onix's outer cover is extremely
durable, protecting the inner tubing
and oxygen barrier from job site
abuse.
9.Onix is crush-resistant, recovering
its shape after being compressed by
vehicles.
Onix allows for a faster, easier, cleaner installation.
The Bottom Line
Onix Staple-Up is a very straightforward, simple-to-install system that is
easily understood by the installer and
the owner. The system doesn't require
special fasteners, metal plates, proprietary tools, heavy concrete, or a special
mechanical room design. It's a system
that works without all the complications.
Onix Staple-Up works, and it works
well. Try it on your next project. Design
the system with our Radiant Works software and you'll have the experience of
22 years of successful radiant system
design guaranteeing it will work like a
champ!
WattsRadiant Literature, May 1, 2003
©WattsRadiant 2003
page 6