DESIGN GUIDE - iheater.comiheater.com/tycothermal/literature/hwat-plus_system_design_guide.pdf ·...

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D E S I G N G U I D E

HWAT-Plus System Design Guide

Contents

Introduction 4

How to use this design guide 6

System description Application information 7

Design steps Plumbing design sheet instructions 8

Design Sheet A: Plumbing Design 9

Electrical design sheet instructions 10

Design Sheet B: Electrical Design 11

Design examples 60-bed nursing home 12

250-bed medium-security prison 14

35-story apartment building 16

500-room hotel 18

Specification CSI Model Specification 20

Installation Installation details 22

3


Introduction

This manual presents Raychem’srecommendations for designing anHWAT-Plus hot water temperaturemaintenance system. Following theseguidelines will result in a reliable,efficient system. For informationregarding other Raychem heat-tracingapplications, consult your Raychemrepresentative.

4


Introduction

Scope

The design information provided isapplicable to the majority of domestichot water temperature maintenanceapplications, but certain conditionsapply. The heater must be installedon copper tubes beneath fiberglassinsulation. It must be powered at208 volts, and the design must fallwithin the temperature require-ments for one of the typical applica-tions outlined below:

5

Pipe temperatures indicated are nomi-nal, and variations will occur. If any ofthe following conditions exist, consultyour Raychem representative: • different nominal pipe temperature• insulation is not fiberglass• insulation differs from Plumbing

Design Sheet, Step 6• ambient temperature range is not as

indicated or may change seasonally• voltage is different

These nonstandard applications canbe handled with factory assistance.

Approvals and Code Compliance

• UL System Listing• BOCA• Uniform Plumbing Code• National Standard Plumbing Code• Southern Building Code Congress• National Electrical Code

Additionally, the HWAT-Plus system isapproved by numerous other stateand local codes and approval agen-cies. Contact your Raychem repre-sentative for more information.

Typical application Ambient Nominal pipe temperature temperature

Hospitals, nursing 74°F to 79°F (23°C to 26°C) 105°F (40°C)homesSchools, prisons, some 70°F to 78°F (21°C to 26°C) 115°F (45°C)hospitalsGeneral domestic 70°F to 78°F (21°C to 26°C) 125°F (50°C)(e.g., offices, hotels, apartments)Kitchens, laundries 70°F to 78°F (21°C to 26°C) 140°F (60°C)


How to use this designguide

General

This manual provides instructions forall engineering disciplines involved inthe design of an HWAT-Plus system.For clarity, the procedure has beendivided into plumbing design andelectrical design. This design guideprovides design and performancedata, recommended design steps,sample design sheets, and examplesthat show typical designs.

Recommended Procedure

1. System description (page 7).Review the system illustrations tounderstand how a typical HWAT-Plussystem operates.

2. Design steps (pages 8 - 11). Review the design steps to gain ageneral understanding of the designprinciples.

3. Design examples (pages 12 - 18). Study the design example which issimilar to your project. Use theexample to gain understanding of thebest design approach for your project.

4. Design sheets (pages 9, 11). Using the design steps as a guide, fillin the design sheets located in thismanual. Copies of the original designsheet may be made for large projectsor for multiple project use.

5. Specification (pages 20, 21). Use the enclosed sample specificationto specify the HWAT-Plus system youhave designed.

6. Installation details (pages 22, 23). Include the typical installation detailson your drawings.

6


System description

Power connection

Heating cable splice

“Electric traced” label

Heating cable and glass tape

End seal

Heating cable tee

Note:

Pipe insulation shown is incomplete.

Required items not supplied byRaychem: • Fiberglass pipe insulation • 30-mA trip ground-fault protection

device

7

HWATTM

The HWAT-Plus system provides tem-perature maintenance of domestic hotwater lines by tracing the supply pipeswith the HWAT-Plus heating cable.Because the water in the supply pipeis directly maintained at temperature,

return lines, pumps, and balancingvalves are all unnecessary. The self-regulating electric heating cablereplaces the small amount of heatwhich pipes lose to the environmentthrough the thermal insulation. Theheating cable automatically compen-sates for temperature variations. Bychanging its power output in responseto the pipe temperature, the HWAT-Plus heating cable will produce morepower where needed and compensatefor temperature differencesautomatically.


Plumbing design sheetinstructions

8

Follow these design steps when filling in copies of the adjacent design sheet.

1.Select the appropriate HWAT-Plus heating cable for your application. Verify thatambient temperatures will be in the range indicated.

Pipe temperatures indicated are nominal, and variations will occur. If theapplication requirements are not as indicated, consult your Raychemrepresentative.

2.Obtain from the electrical department the maximum available 208-V circuitbreaker size: 15, 20, or 30 amps.

3.Determine the maximum circuit length. Maximum circuit lengths are based onsystem start-up at minimum 60°F (15°C) water temperature.

4.Lay out the circuits in segments (floors, risers, zones, wings, etc.), staying withinthe maximum circuit length. Identify each circuit and measure the circuit length.See examples on pages 12-19 for additional circuit layout advice.

Note on the drawings the pipes to be traced, and show the circuits using thefollowing symbols (include circuit no. within symbol):

Circuit continued on another sheet

End of circuit

Hot water supply pipe traced with HWAT-Plus heating cable

Power connection

5.Provide equipment to allow for thermal expansion in all closed sections of pipingdownstream of check or pressure-reducing valves. For example, in a high-risebuilding use an expansion tank or pressure relief valve at each pressure zone.

6.Specify the correct thicknesses and diameters of fiberglass insulation for eachcopper pipe size. Pipe sizes up to 11/4 inch require insulation that is oversizedin diameter by 1/4 inch to allow for installation over the heating cable. Forexample, a 1-inch diameter pipe requires 1-inch thick insulation, with a 11/4-inchinside diameter.

7.Include clauses in the project specification to provide, install, and test theHWAT-Plus system. State the appropriate insulation thicknesses. A CSI formatspecification is located on page 20.

8.Transmit copies of the plumbing design sheets to the electrical engineer.

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3

Note:

The design sheet shown on page 9 isavailable in tablet form. Contact yourRaychem representative.

Prepared by:

Checked by:

Date:

Page no. of

Use HWAT-

Maximum circuit

breaker: A

Maximum circuit

length:

Transmit this table tothe electrical engineer.

Provide

in pipe sections

R HWAT-Plus SystemDesign Sheet

1. Select the HWAT-Plus heating cable for the application.

2. Maximum 208-V circuitbreaker size:

Project name:

Area of building:

Project No.:

5. Provide for thermalexpansion.

6. Specify the followingthicknesses of fiberglassinsulation:

7. Include clauses in the project specification to provide, install, and test the HWAT-Plussystem. State appropriate fiberglass insulation thicknesses.

Application Ambient Nominal pipe Heating temperature temperature cable type

Hospitals, nursing homes 74°F to 79°F 105°F (40°C) HWAT-B2Schools, prisons, some hospitals 70°F to 78°F 115°F (45°C) HWAT-G2General domestic (offices, hotels) 70°F to 78°F 125°F (50°C) HWAT-Y2Kitchens, laundries 70°F to 78°F 140°F (60°C) HWAT-R2

Circuit Heating Risers, zones Drwg. Approx.no. cable type or floors served no. length

3. Determine the maximumcircuit length.

4. Lay out the HWAT-Pluscircuits. Identify andmeasure each circuit.

Maximum circuit length in feet (meters)

Circuit HWAT-B2 HWAT-G2 HWAT-Y2 HWAT-R2Breaker

30 amp 800 (240) 800 (240) 800 (240) 500 (150)20 amp 800 (240) 700 (210) 500 (150) 330 (120)15 amp 800 (240) 520 (155) 350 (105) 250 (75)

Equipment to allow for thermal expansion should beprovided in all closed sections of piping downstream ofcheck or pressure-reducing valves.

Pipe size Fiberglass insulation(inches) thickness (inches)

1⁄2" - 1" 1"

11⁄4" - 2" 11⁄2"

21⁄2" - 6" 2"

Note: for pipe sizes 11/4" and smaller, use 1/4" larger diameter insulation to allow room forinstallation over cable.

Part A: Plumbing Design

15 amp 20 amp 30 amp

9


Electrical design sheetinstructions

Follow these design steps when filling in copies of the adjacent electrical designsheet.

1.Based on the information on the plumbing design sheets, note the HWAT-Pluscable type and fill in the electrical design table. Use Table 1 to determinebreaker size and steady-state current draw. Choose the smallest circuit breakersize which can accommodate the circuit length.

Junction box and panel locations should be based on circuit layouts provided bythe plumbing engineer.

If desired, steady-state current may be calculated to determine transformersizing. Please note that the steady-state current table chart is used to estimatesteady-state current only. Current draw at start-up on a cold pipe will be higher.

The HWAT-Plus system design is based on operation at 208 volts. If differentconditions occur, consult the factory for assistance.

2.Include the finished table on the electrical drawings.

3.Call out 30-mA ground-fault protection device in Division 16 of the specificationand on the drawings. These ground fault breakers are a system requirement.Suitable circuit breakers are available from Westinghouse (types QPGFEP andQBGFEP) and Square D (types QOEPD and QOBEPD).

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Note:

The design sheet shown on page 11is available in tablet form. Contactyour Raychem representative.


Part B: Electrical Design

1. Fill in the electrical design table below, using the information provided on the plumbingdesign sheet.

Electrical Design Table

HWAT-Plus cable type:

Circuit Approx. Voltage Breaker Steady- J-box Panelno. length Ground Size state location no.

fault (Table 1)current for power

protection (Table 1) connection

Table 1

Heating Circuit length Circuit Steady-statecable type in feet (meters) breaker* current draw

HWAT-B2 800 (240) 15 amp .006 amp / ft @ 105°F

800 (240) 20 amp (.020 amp / m @ 40°C)

800 (240) 30 amp

HWAT-G2 520 (155) 15 amp .008 amp / ft @ 115°F

700 (210) 20 amp (.026 amp / m @ 45°C)

800 (240) 30 amp

HWAT-Y2 350 (105) 15 amp .010 amp / ft @ 125°F

500 (150) 20 amp (.033 amp / m @ 50°C)

800 (240) 30 amp

HWAT-R2 250 (75) 15 amp .015 amp / ft @ 140°F

330 (100) 20 amp (.049 amp / m @ 60°C)

500 (150) 30 amp

2. Include the finished electrical design 3. Call out 30-mA ground-fault protection table on the electrical drawings. device in Division 16 of the specification

and on the drawings.

208

208

208

208

208

30 mA

30 mA

30 mA

30 mA

30 mA

Project name:

Area of building:

Project No.: Prepared by:

Checked by:

Date:

Page no. of

Include the electricaldesign table in theelectrical drawings.

11

*Use a ground-fault protection devicewith a nominal 30-mA trip level in eachcircuit.


Design example: 60-bed nursing home*

*Design example has been simplified for clarity.

The Decision

The plumbing engineer was laying outthe piping for the domestic hot watersystem for St. Mary’s Nursing Home, athree-story, sixty-bed, long-term healthcare facility. The engineer did notbelieve it necessary to recirculate therisers and was going to run two recir-culation loops, one for each wing, inthe ground floor ceiling space. How-ever, the engineer decided that thereturn lines would have to take thesame route as the supply lines. In thissituation, the engineer knew theHWAT-Plus system would provide themore economical design. Further-more, the client had indicated thepossibility of extending either wing atsome time in the future. The engineerknew that by using HWAT-Plusproducts, the system could be easilyexpanded if and when the client decid-ed to do so.

Plumbing Design

The plumbing engineer began to fill inan “HWAT-Plus System Design Sheet,Part A: Plumbing Design.” The nursinghome required a nominal temperatureof 105°F, and HWAT-B2 was chosen.The engineer thought it would beuseful to be able to isolate either wingfor maintenance, so it was decided torun two separate circuits. Using 15-amp circuit breakers, a maximumcircuit length of 800 feet could be run,which was sufficient for either wing.Alternatively, just one circuit couldhave been run, with a tee connectionat the intersection of the pipes fromthe two wings. The plumbing engineerfilled in the table on the design sheetand handed it over to the electricalengineer.

The plumbing engineer noted thepipes to be traced with HWAT-Plusheating cables on the drawings. Hethen inserted the standard clauses toprovide, install and test the HWAT-Plus system, and called out the cor-rect thicknesses of fiberglass insula-tion, in Division 15 of the specification.

Completed HWAT-Plus SystemDesign Sheet, Part A: PlumbingDesign

12

Prepared by:

Checked by:

Date:

Page no. of

Use HWAT-

Maximum circuit

breaker: A

Maximum circuit

length:


Check here if addition-al circuits are listed on reverse.

Provide

in pipe sections




Project name:

Area of building:

Project No.:






Circuit Heating Risers, zones, Drwg. Approx.no. cable type or floors served no. length



See reverse to makeadditional Circuit DesignTable entries.


Circuit HWAT-B2 HWAT-G2 HWAT-Y2 HWAT-R2breaker

30 amp 800 (240) 800 (240) 800 (240) 500 (150)20 amp 800 (240) 700 (210) 500 (150) 330 (120)15 amp 800 (240) 520 (155) 350 (105) 250 (75)



1⁄2" - 1" 1"

11⁄4" - 2" 11⁄2"

21⁄2" - 6" 2"




Refer to the HWAT-Plus Design Guide for complete design instructions.

Isometric of building

St. Mary's Nursing Home

All

E10 DG

KC

11/4/90

23 80

B2

15

800 ft

1 B2 EW Wing 13 280'

2 B2 NS Wing 13 180'


Design example: 60-bed nursing home*


Electrical Design

Upon receiving the HWAT-PlusPlumbing Design Sheet, the electricalengineer took out an “HWAT-PlusSystem Design Sheet, Part B:Electrical Design.” In the electricaldrawings, junction boxes were locatednear each power connection. It wasdecided to power both circuits fromthe same panel. Circuit breaker sizesand steady-state current werecalculated and included on a table inthe electrical drawings. The need for aground-fault protection device in eachcircuit was noted on the electricaldrawings.

Completed HWAT-Plus SystemDesign Sheet, Part B: ElectricalDesign

HWAT-Plus heat-tracing layoutshown on plumbing drawing 13






Circuit Approx. Voltage Breaker Steady- J-box Panelno. length Ground- Size state location no.



208

208

208

208

208

30 mA

30 mA

30 mA

30 mA

30 mA

Project name:

Area of building:


Checked by:

Date:

Page no. of




See reverse for additional circuit entries

1

2 H

1

2NOTE

All heat-tracingcable to be HWAT-B2

LEGEND

Beginning and end of HWAT-Plus heat-tracing circuit

Water heater

Riser up

PLAN OF GROUND FLOOR HOT WATER PIPING

1 1

H

St. Mary's Nursing Home

All

HWAT-B2

E10 BW

JJ

11/5/90

13 83

1 280' 15 1.7 A J-17 P-3

2 180' 15 1 A J-21 P-3


Design example: 250-bed, medium-security prison*


The Decision

Reviewing the architectural drawings,the plumbing engineer observed thatthe design consisted of about a dozentwo-story “pods” arranged around anexpanse of open space. For securityreasons, the County had requestedthat mechanical equipment and piping,and the associated pipe openings, bekept to an absolute minimum. Thelayout of the cells in each pod did notallow any “shortcut” for return pipingfor a recirculation loop; it would haveto follow the same corridor as thesupply piping. The plumbing engineerknew from experience that in thesekinds of situations, the HWAT-Plussystem would be more economicalthan recirculation.

Plumbing Design

For the prison application, HWAT-G2was selected to maintain nominal tem-perature of 115°F. Each pod would beprovided with a separate water heaterand it was not considered necessaryto heat trace the risers. Upon measur-ing the length of the ground floorpiping, the plumbing engineer found itwas possible to trace the entire pipingin each pod with a single HWAT-G2circuit and stay within the capacity of a15-amp ground-fault circuit breaker.This would allow the heating cable tobe conveniently powered from theelectrical panel in the mechanicalroom. The plumbing engineer decidedthat the situation was sufficiently sim-ple to ignore marking on the plumbingdrawing the lines to be heat traced.Instead, the extent of the heat tracingcould be called out in the notes. Theplumbing engineer filled in the table onthe design sheet and faxed it to theelectrical engineer.

The plumbing engineer then insertedthe standard clauses to provide,install, and test the HWAT-Plus sys-tem, and called out the correct thick-nesses of fiberglass insulation, inDivision 15 of the specification.


14

Prepared by:

Checked by:

Date:

Page no. of

Use HWAT-

Maximum circuit

breaker: A

Maximum circuit

length:



Provide

in pipe sections




Project name:

Area of building:

Project No.:












30 amp 800 (240) 800 (240) 800 (240) 500 (150)20 amp 800 (240) 700 (210) 500 (150) 330 (120)15 amp 800 (240) 520 (155) 350 (105) 250 (75)



1⁄2" - 1" 1"

11⁄4" - 2" 11⁄2"

21⁄2" - 6" 2"





Sherwood County Prison

Typical Pod

C-15 MW

AJ

4/30/91

12 34

G2

15

520 ft

None required

1 G2 All h.w. P5 270'

piping


Design example: 250-bed, medium-security prison*


Electrical Design

The electrical engineer took out the“HWAT-Plus System Design Sheet,Part B: Electrical Design” and filled inthe table from the data on the plumb-ing engineer’s transmittal.The electri-cal engineer confirmed that a 15-ampbreaker was adequate, and calculatedthe steady-state current. A junctionbox was located adjacent to the begin-ning of the heating cable circuit, andits number and the number of theelectrical panel in the table werenoted. A draftsperson copied the tableonto the electrical drawings, alongwith a note calling out the need for aground-fault protection device in eachcircuit.


Ground floor hot water pipingdiagram 15

H

NOTE

Heat-trace all HWdistribution piping withHWAT-G2 heating cable. Do not trace branches orrisers.









208

208

208

208

208

30 mA

30 mA

30 mA

30 mA

30 mA

Project name:

Area of building:


Checked by:

Date:

Page no. of




See reverse for additional circuit entries

Sherwood County Prison

Typical Pod

HWAT-G2

C-15 HB

BF

5/4/1

14 40

1 270' 15 A 2.2 A A-5 P-1

Waterheater

Riser up

HW supplypiping

LEGEND

H


Design example: 35-story apartmentbuilding*


The Decision

The plumbing engineer was faced withlaying out the hot water piping for the35-story Washington Towers. The pip-ing was relatively complex, making itespecially important to balance thesystem adequately. As requested bythe developer, the architect hadsqueezed in the maximum number ofresidential floors by working to theminimum headroom allowed by code.The plumbing engineer was requiredby code to divide the building intothree pressure zones. However, therewould be great difficulty in running the

horizontal supply and return lines nec-essary in each zone, given the verylimited space provided above thedropped ceilings. And there was notany room for the booster heaters andpumps for the recirculation system.

The plumbing engineer decided thatan HWAT-Plus system would elimi-nate the need for horizontal piping andadditional heaters or pumps. Therisers could run continuously from topto bottom, broken only by pressure-reducing valves at the 11th and 23rdfloors. The plumbing engineer notedthat the need for flow balancing wascompletely eliminated by using theHWAT-Plus system.


Riser diagram showingoriginally proposedrecirculation system

16

Prepared by:

Checked by:

Date:

Page no. of

Use HWAT-

Maximum circuit

breaker: A

Maximum circuit

length:



Provide

in pipe sections




Project name:

Area of building:

Project No.:












30 amp 800 (240) 800 (240) 800 (240) 500 (150)20 amp 800 (240) 700 (210) 500 (150) 330 (120)15 amp 800 (240) 520 (155) 350 (105) 250 (75)



1⁄2" - 1" 1"

11⁄4" - 2" 11⁄2"

21⁄2" - 6" 2"





Plumbing Design

Following the plumbing design sheet,the plumbing engineer selectedHWAT-Y2. Having estimated that asingle circuit length on a 20-amp cir-cuit breaker could run the completeheight of the building, the engineermarked an HWAT-Plus circuit on eachof the four risers and sent copies ofthe plumbing drawing and the designsheet to the electrical engineer.

Standard clauses to provide, install,and test the HWAT-Plus system wereincluded in Division 15 of the specifi-cation. To provide pressure relief inthe piping during system startup, anexpansion tank was indicated on eachriser at each PRV.

BH

BH

BH

H

LEGEND

Waterheater

Pressure-reducingvalve

Balancingvalve

Boosterheater

Recirc.pump

Supplypiping

Returnpiping

H

BH

Washington Towers

Block A

F21 JB

MP

1/10/91

41 80

Y2

20

500 ft

Expansion tank

All risers at

floors 11 and

23

1 HWAT-Y2 riser 1

P5 370'

2 HWAT-Y2 riser 2

P5 370'


Design example: 35-story apartmentbuilding*


Electrical Design

The electrical engineer looked at theplumbing drawing, and at the “HWAT-Plus System Design Sheet, Part A:Plumbing Design,” and determinedthat it was most convenient to powerall the circuits from the penthousemechanical room. Junction boxeswould be located at the beginning ofeach circuit and power run from asingle panel. The electrical engineercompleted the “HWAT-Plus SystemDesign Sheet, Part B: ElectricalDesign” by calculating the breakersizes and the steady-state currents.The finished table was included in theelectrical drawings, along with a notecalling for a ground-fault protectiondevice in each circuit.


Riser diagram using HWAT-Plus system

H

1 2 3

1 2 3

4

4

LEGEND

Waterheater

Pressure-reducingvalve

Expansiontank

Beginningand endof HWAT-Plusheatingcableinstalledon supplypiping

H

3

3

NOTE

All heat-tracingto be HWAT-Y2

17









208

208

208

208

208

30 mA

30 mA

30 mA

30 mA

30 mA

Project name:

Area of building:


Checked by:

Date:

Page no. of




See reverse for additional circuit entries.

Washington Towers

Block A

HWAT-Y2

F21 VL

PB

1/20/92

26 40

1 370' 20 A 4 A A-5 R2-4

2 370' 20 A 4 A A-8 R2-4

3 370' 20 A 4 A A-18 R2-4

20 A 4.3 A A-19 R2-4


Design example: 500-room hotel*


The Decision

The plumbing engineer reviewed thearchitectural drawings for a new hotelplanned by National Resorts. Thebuilding consisted of six floors of guestrooms over a commercial area con-taining a health club, restaurants, con-ference rooms, shops, offices, and alaundry. The plumbing engineer decid-ed to deliver water from the boiler at140°F directly to the kitchens andlaundry, and to mix to 125°F fordomestic hot water.

The HWAT-Plus system was chosenrather than recirculation becauseNational Resorts insisted that there beno delay in getting hot water from anyfixture. An HWAT-Plus system waschosen to accommodate all the archi-tectural and construction changes thatwere bound to occur before thesystem was operating.

Plumbing Design

Following the “HWAT-Plus SystemDesign Sheet, Part A: PlumbingDesign,” HWAT-R2 was selected forthe 140°F line running out of the boilerto the kitchens and laundry, andHWAT-Y2 for the domestic hot watersystem. Separate design sheets wereused for each HWAT-Plus cable type.After reviewing the circuit length table,it was determined that the entiredomestic hot water piping could betraced with only two HWAT-Y2 circuitsby utilizing a 30-amp circuit breaker.However, the plumbing engineerdecided to lay out the heating cable insmaller discrete zones to facilitatepartial shutdown of the system formaintenance. Circuits staying withinthe maximum length for a 15-ampbreaker were indicated on thedrawing, and the table in the designsheets was completed. A copy of thedrawing and the design sheets weresent to the electrical engineer.

Division 15 of the specification for thedomestic hot water lines called outstandard clauses to provide, install,and test the HWAT-Plus system.

Completed HWAT-Plus SystemDesign Sheet, Part A: PlumbingDesign (for HWAT-Y2 only;design sheet for HWAT-R2 notshown)

18

Prepared by:

Checked by:

Date:

Page no. of

Use HWAT-

Maximum circuit

breaker: A

Maximum circuit

length:



Provide

in pipe sections




Project name:

Area of building:

Project No.:












30 amp 800 (240) 800 (240) 800 (240) 500 (150)20 amp 800 (240) 700 (210) 500 (150) 330 (120)15 amp 800 (240) 520 (155) 350 (105) 250 (75)



1⁄2" - 1" 1"

11⁄4" - 2" 11⁄2"

21⁄2" - 6" 2"





National Resorts Hotel

Tower 1

P19 SK

JS

7/21/90

42 60

Y2

15

350 ft

None required

1 Y2 horiz. dist H3 95'

2 Y2 main riser H3 110'

3 Y2 risers B,C,D H3 240'

4 Y2 risers F ,G,H H3 230'

✓


Design example: 500-room hotel*


Electrical Design

The electrical engineer looked at thelayout of the circuits and assignedjunction-box and panel locations foreach circuit according to the electricaldrawings. Filling in the information onthe “HWAT-Plus System DesignSheet, Part B: Electrical Design,” theengineer calculated the breaker sizeand the steady-state current for eachcircuit. The completed table, with anote that the circuit breakers wouldincorporate 30-mA ground-fault pro-tection, was then transferred to theelectrical drawing.

HWAT-Plus heat-tracing layoutshown on plumbing drawing 19

2 3 3 3 44 4

3 4

56

56

6

6

H

1 2

5

51

5 5

LEGEND

Waterheater

Beginningand endof HWAT-Plusheatingcablecircuitinstalledon supplypiping

H

2

2

NOTE

All heatingcables to beHWAT-Y2 exceptcircuit no. 1which shall beHWAT-R2









Table 1

Heating Circuit length Circuit Steady-statecable type in feet (meters) breaker* current draw

208

208

208

208

208

30 mA

30 mA

30 mA

30 mA

30 mA

Project name:

Area of building:


Checked by:

Date:

Page no. of




See reverse for additional circuit entries.

*Use a ground-fault protection devicewith a nominal 30-mA trip level in eachcircuit.

National Resorts Hotel

1

HWAT-Y2

P19 GL

BF

7/25/90

18 45

1 95' 15 A 1 A CF-3 R-3

2 110' 15 A 1.1 A J-21 M-4

3 240' 15 A 2.4 A T-6 S-8

4 230' 15 A 2.3 A T-32 S-14

5 260' 15 A 2.6 A CR-6 R-6

Completed HWAT-PLUSSystem Design Sheet, Part B:Electrical Design

✓


CSI Model Specification

Raychem HWAT-Plus

Hot Water TemperatureMaintenance System

Part 1 - General

1. Furnish and install a UL-listed system of electric self-regulatingheating cable and components formaintaining the water temperaturein the hot water lines as indicatedon the drawings. The cable shallutilize a radiation-crosslinked con-ductive polymer as the heatingelement, and the cable shall bespecifically designed, manufac-tured, and UL listed for domestichot water temperaturemaintenance.

2. Submittals:i) Copy of UL file indicating the

heating cable is specificallylisted to provide supplementaryheating to hot water servicesupply systems utilizing thermal-ly insulated metal or plasticpipe.

ii) Manufacturer’s catalog cutsshowing materials and perfor-mance data.

iii) Project list of at least 20 pro-jects, installed for at least 5years, with at least 2000 ft (600 m) of heating cable in eachproject.

Part 2 - Materials

1. Construction: The self-regulating heating cableshall consist of two (2) 16-AWG(1.2-mm2) nickel-coated copper buswires embedded in a radiation-crosslinked conductive polymercore. It shall be covered by aradiation-crosslinked, polyolefin,dielectric jacket surrounded by apolymer-coated aluminum wrap,and enclosed in a tinned copperbraid of 14 AWG (2.5 mm2) equiva-lent wire size. The braid shall becovered with a (nominal) 40-mil (1-mm) polyolefin outer jacket, colorcoded for easy identification.

2. Mechanical: The cable shall have a minimumcut-through resistance of 600 lb perCSA 22.2 0.3 Cutting Test 4.14.The cable shall have a minimumimpact resistance of 25 ft•lb per UL1588.11. The cable shall withstanda glancing impact of 22 ft•lb per UL1581.590. The cable shall have aminimum abrasion resistance of7000 cycles per UL 719.19. Thecable shall withstand a crush resis-tance of 4500 N per IEEE 515Deformation Test 5.1.5.

Part 3 - Performance

1. Operating temperatures: The system shall maintain a nomi-nal temperature of [105°F (40°C),115°F (45°C), 125°F (50°C), 140°F(60°C)] as noted on the drawings,at 208 V.

2. Maintenance temperature: Each hot water system temperatureshall be maintained using only oneproduct. Temperatures shall bemaintained with straight runs ofheating cable on the pipe.

3. Power control (self-regulating index): The slope of the power/tempera-ture curve shall be such that thepower of the heating cable shallincrease with decreasing temper-ature at a rate of at least 0.028W/ft•°F (0.16 W/m•°C) from 50°F(10°C) to 100°F (38°C).

4. Long-term thermal stability (as determined by accelerated testing): The power retention of the heatingcable shall be at least 90% after300 cycles between 50°F (10°C)and 212°F (100°C).

5. High temperature withstand: The heater shall not decrease inresistance, overheat, or burn whenpowered at 208 V and exposed to400°F (205°C) in an oven for 30minutes.

20


CSI Model Specification

Raychem HWAT-PlusHot Water TemperatureMaintenance System

Part 4 - Manufacturer

1. Experience: The manufacturer shall have morethan ten years experience with self-regulating heating cables for tem-perature maintenance of domestichot water.

2. Acceptable manufacturer: Raychem Corporation

Part 5 - Execution

1. Installation: The system shall be installedaccording to the drawings and themanufacturer’s instructions. Theinstaller shall be responsible forproviding a functional system,installed in accordance with appli-cable national and local coderequirements. Each circuit shall beprotected with a 30-mA ground-fault protection device.

2. Testing i) Procedure: Measure the heater

circuit continuity and the insula-tion resistance between thebraid and bus wires with a 2500-Vdc megohmmeter (megger).

ii) Timing: The tests should be per-formed after the pipe insulationhas been installed and prior toinstallation of wall or ceilingpanels, and shall be witnessedby the Construction Managerand the manufacturer or themanufacturer’s representative.

iii) Acceptable results: The heatercircuit shall be continuous andmegger readings shall be atleast 20 megohms regardless ofheater length. Circuits yieldingunacceptable readings must berepaired or replaced.

iv) Submittal of results: Submitrecords of the test data to theConstruction Manager.

21


Installation details

22

Component Usage Heater Allowance*

Power Connection Kit One per circuit 2 ft (.6 m)Splice Connection Kit As required 2 ft (.6 m)Tee Connection Kit At tees in traced piping 3 ft (1 m)End Seal Kit One per circuit and one per tee –Glass Tape Use tape to attach heating cable –

to pipe every 2 ft (.6 m)“Electric Traced” Labels Place at 10-ft (3-m) intervals on –

alternating sides of insulation

*Raychem recommends a “service loop” (notshown) in the HWAT-Plus heating cables at con-nections or places in the piping where future ser-vice is expected. This extra length of cable willmake any maintenance easier to accomplish. Besure to consider service loops when calculating thetotal length required for an HWAT-Plus system.

ELECTRICTRACED

ETL “electric traced” label. Place at 10-ft (3-m) intervalson alternating sides ofinsulation.

HWK-XP power connection kit(junction box not included). Use one per circuit. Allow for a2-ft (.6-m) service loop.*

HWK-XS splice kit. Use as needed. Allow for a 2- ft(.6-m) service loop.

HWK-XT tee kit.Use at tees in traced piping.Allow for a 3-ft (1-m) serviceloop.

GT-66 glass tape.Use tape to attach heatingcable to pipe every 2 ft (.6 m).One roll will handleapproximately 50 ft (15 m).

HWK-XE end seal.Use one per circuit plus oneper tee. No service looprequired.

Note:

Required items not supplied by Raychem:• Fiberglass pipe insulation• 30-mA ground-fault protection device


Installation details

23

“Electric traced” label

Heating cable splice

Heating cable and glass tape

Power connection

End sealHeating cable tee

HWATTM

All of the information in this booklet, including illustrations, is believed to bereliable. Users, however, should independently evaluate the suitability of eachproduct for their application. Raychem makes no warranties as to the accuracyor completeness of the information, and disclaims any liability regarding its use.Raychem’s only obligations are those in the Standard Terms and Conditions ofSale for this product, and in no case will Raychem be liable for any incidental,indirect, or consequential damages from the sale, resale, use, or misuse of theproduct.

Raychem CorporationConstruction Products Group300 Constitution DriveMenlo Park, California 94025-1164(800) 542-8936Fax (650) 361-6036

Raychem Canada Ltd.3245 American DriveMississaugaOntario, Canada LV4 1N4(800) 387-3993Fax (416) 671-0972

1992

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DESIGN GUIDE - iheater.comiheater.com/tycothermal/literature/hwat-plus_system_design_guide.pdf ·...

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