this, they are not used as in instal-lation tool. Residential projects donot require a layout to be generat-ed.

5. Time. Depending on the time ofyear and the complexity of theproject, turn around times canrange from a day to a couple ofweeks.

In light of these issues, Watts Radiant isoffering a sort of “primer” to the actualCAD layout. This primer will illustratethe main concerns installers have thattend to generate the need for a customlayout. If this primer can be used in leuof a custom layout, please do so. If acustom layout is still required, or if moredetail illustrations are needed, please callWatts Radiant’s CAD department.

Introduction

Watts Radiant offers a wide range ofproducts (Onix, WaterPEX andWaterPEXB) and services used in theinstallation and operation of radiant floorheating and snowmelting systems. Oneof those services include custom generat-ed CAD layouts.

Over the years we have discovered sever-al “truths” to this service.

1. The layouts are used mainly to verify the Radiant Works design,showing that each zone will usethe amount of tubing specified.

2. These layout can not be used as anexact representation. There arealways items on a jobsite that cannot be represented in a two-dimen-sional drawing, such as josite crossmembers, waste drainage, ventila-tion ducts, etc. These items willalways cause an on site adjustmentto the provided layout.

3. Most layouts never get used oncethe tubing arrives at the jobsite.

4. Most layouts center around largercommercial projects that requiresome sort of material verificationfor submittal purposes. Beyond

Piping Layout Primer3131 W. Chestnut Expressway

Springfield, MO 65802ph: 417.864.6108fax: 417.864.8161

www.wattsradiant.com

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Tubing Options

General Information

Watts Radiant offers two main types oftubing, Onix, an EPDM product andRadiantPEX, a cross-linked polyethylene product.

Onix

Onix is a polymer-rich, multi-layer,industrial-grade hose used for hydronicheating and snowmelting applications. Itcontains five distinct structural layers.The Durel inner tube is a peroxide-cured, cross-linked EPDM(Ethylene Propylene Diene Monomer).This layer is wrapped with a ductile 00grade aluminum oxygen barrier, calledAlumaShield. A contour layer of Durel(EPDM) is extruded over theAlumaShield. Spiral reinforcing cords ofAramid fibers are applied over the contour layer. This reinforcing is covered with the outer HiGuard covercomposed of sulfur-cured, cross-linked EPDM.

Onix has a maximum working temperature of 180°F at 100 psi. Burstpressure is greater than 800 psi at 70°F;greater than 600 psi at180°F.

RadiantPEX

RadiantPEX is a cross-linked polyethylene tubing used for radiant floorheating and snowmelting applications.RadiantPEX is manufactured with anintegral ethylene vinyl alcohol (EVOH)DIN Standard O2 barrier that limits oxygen diffusion through the walls of thetubing to less than 0.10g/m3/day at 104°Fwater temperature.

RadiantPEX has a maximum workingpressure/temperature of 160 psi at 73.4°F,100 psi at 180°F, 80 psi at 200°F.

Onix and RadiantPEX have specific installation advantages for certain applications and jobsiteconditions and should be chosen based on those needs. More detailed information on each tub-ing option can be found in their corresponding submittals and installation manuals.

EPDM Outer Cover

Aramid Reinforcement

EDPM Boding Layer

AlumaShield

EPDM Inner Tube

EVOH Oxygen Barrier

Adhesive Layer

Cross-Linked Polyethylene

Ideal manifold locations include undervanities and in closets. These areas arehidden from view, but remain readilyaccessible. Do not install manifoldsalong an exterior wall. Exterior wallsmake it almost impossible to insulatebehind the manifold enclosure, increasingthe risk of freezing due to exterior weather conditions.

Try to keep the manifold horizontal whenmounting. This position will allow thevent/purge assemblies to work properly.If no vent/purge assembly is installed onthe manifolds, they can be installed in thevertical position. Keep in mind verticallymounted manifolds increase the risk ofair locks and can increase the difficulty ofthe initial purge process.

Manifold Details

General Information

The basic rules apply for both both Onixand RadiantPEX. It is advised to installthe manifolds in a reverse/return arrangement. This will ensure properflow through each circuit on the manifoldand will help in post-fill balancing.

Each tubing option will have specificconnection details that must be followed.See the corresponding literature on howto properly perform each connection.

The manifolds can be installed in a variety of locations, each specific to theapplication. In all cases, it is advised toinstall the manifolds so they remainaccessible after the installation is complete. This will allow for anyrequired post-fill balancing or for futurepurging if the system needs to be flushedand re-filled.

Watts Radiant offers a recessed manifoldenclosure, designed to be installed in astandard wall construction. Each inclo-sure comes with a locking cover andmanifold mounting supports.

Manifolds can be located within the jositecavity or other location as long as accessis maintained.

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Sheet Metal Screw

Washer

Door Frame

Cross Brace

Locking / Removable Door

Manifold Bracket Bolt

Manifold Bracket Mount

Wing Bolt

BoxElevators

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Main Box

Manifold Support Bracket

Side Nut

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Slab installations are installed using oneof two methods, a Single Serpentine or aDouble Serpentine. The Onix tubing willusually use the Double Serpentinemethod while RadiantPEX will generallyuse the Single Serpentine. Even thoughthis is typically how each piping optionis installed, it is not a requirement. If theconditions deem necessary, Onix can beinstalled using a Single Serpentinemethod and PEX as a Double.

General Tips

1. Support manifolds high enough abovethe slab to account for the concreteand any post pour adjustments.

2. Keep all circuits at least 6” fromexposed walls.

3. Make sure tubing is deep enough inthe slab when going under interiorwalls or cut joints.

4. Use all tubing designated for the givenzone. Try to use any excess tubing byrunning it along exposed walls.

5. If all of the tubing can not be used, tubing can be cut within 10% of thetotal circuit length. If 200 ft circuitsare used, they can be cut to 180 ftwithout affecting fluid flow.

Slab Applications

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Double Serpentine Single Serpentine

Thin Slab installations are installed usingone of two methods, a Single Serpentineor a Double Serpentine. The Onix tubingwill usually use the Double Serpentinemethod while RadiantPEX will generallyuse the Single Serpentine. Even thoughthis is typically how each piping optionis installed, it is not a requirement. If theconditions deem necessary, Onix can beinstalled using a Single Serpentinemethod and Pex as a Double.

General Tips

1. Support manifolds in the wall cavityusing one of the approved methodsmentioned earlier.

2. Keep all circuits at least 6” fromexposed walls.

3. Run tubing around all built-ins and allinterior walls.

4. Use all tubing designated for the givenzone. Try to use any excess tubing byrunning it along exposed walls.

5. If all of the tubing can not be used,tubing can be cut within 10% of thetotal circuit length. If 200 ft circuitsare used, they can be cut to 180 ftwithout affecting fluid flow.

Thin Slab Applications

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Double Serpentine Single Serpentine

Underfloor installations are typicallyinstalled using a Single Serpentinemethod. Other techniques can be foundin the corresponding installation manuals.Onix will be installed by stapling the tubing directly to the subfloor whileRadiantPEX will be installed with the useof a heat transfer plate or LockDowns.Both follow the single serpentine layout.

General Tips

1. Manifolds can be installed either inthe wall cavity or in the joist cavity.

2. Keep all circuits at least 6-8” fromexposed walls.

3. Make sure tubing supported associated with the correspondinginstallation method.

4. Use all tubing designated for the givenzone. Try to use any excess tubing byrunning it along exposed walls.

5. If all of the tubing can not be used,tubing can be cut within 10% of thetotal circuit length. If 200 ft circuitsare used, they can be cut to 180 ftwithout affecting fluid flow.

Underfloor Applications

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Onix: Single Serpentine PEX Plates: Single Serpentine

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Slab

Onix

Rewire

Base

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Single Serpentine Layout: This is the easiestof all the layout patterns to visualize. Simply start at one end of the zone, walking back and forth until the zone is filled, or until you need to return to the manifold and begin the next circuit.

Slab

Single Serpentine Layout with Banding: Banding is used along exposed walls or areas of excessive heat loss. Banding allows for more tubing to be installed in a given area, which increases the floors heating output. This higher output helps off-set the heat loss. Banded spacing is usually 4 ft. in from the exposed wall and is usually half the spacing as the main room.

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Slab

Frame Floor: Long Manifold

Long manifolds are installed perpendicular to the floor joists. To ensure balanced flow through each circuit, a reverse return method is recommended. A reverse return manifold requires a third copper line to be ran. This extra line allows each circuit to "see" the same total manifold length, thus creating a balanced system.

Flow

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Foil Faced InsulationJoist

Sub Floor

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The above illustration shows a serpentine layout with a banded area running parallel to the exposed wall. The banded area is spaced at 4" oc.

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Frame Floor: Step by Step

The above illustration shows a sperpentine layout with a banded area running perpendicular to the exposed wall. The banded area is spaced at 4" oc.

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The above illustration shows how to "pick up" a bay when the previous circuit terminates mid-run. The second circuit loops back down the open bay from the far end. The remainder of the circuit is installed in the same fashion as the first circuit.

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Single Serpentine Layout with Banding: Banding is used along exposed walls or areas of excessive heat loss. Banding allows for more tubing to be installed in a given area, which increases the floors heating output. This higher output helps off-set the heat loss. Banded spacing is usually 4 ft. in from the exposed wall and is usually half the spacing as the main room.

Frame Floor

Step 1

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Frame Floor: Counter Flow Method

Step 2:

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Frame Floor: Counter Flow Method

Step 3:

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Frame Floor: Counter Flow Method

Frame Floor: Counter Flow Method

Step 4:

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Step 5:

Frame Floor: Counter Flow Method

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Frame Floor: Long Manifold

Long manifolds are installed perpendicular to the floor joists. To ensure balanced flow through each circuit, a reverse return method is recommended. A reverse return manifold requires a third copper line to be ran. This extra line allows each circuit to "see" the same total manifold length, thus creating a balanced system.

Flow

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