Honeywell 6442, HT02524ANAX, 6261, 6262, HT04554ANAX Sizing Guide
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Automatic Home Standby Generators
Sizing Guide
Important Notices
This booklet is designed to familiarize estimators and installers with proper sizing guidelines for residential and commercial
generators. The information is not comprehensive, nor does it replace or supercede any material contained in any of
the written documents shipped with the equipment. This booklet should only be used in conjunction with the Owner’s
Manual, Installation Manual and other technical documents shipped with each product. Always read all accompanying
documentation carefully before attempting to install any generator, transfer switch or related equipment.
HOW TO USE THIS BOOKLET:
Within this booklet, you will nd electrical load information, plus an outline of generator surge capability, fuel pipe sizing,
liquid propane tank sizing, and UPS / generator compatibility. The worksheet pages can be removed from the book and
photocopied to create additional Onsite Estimating Sheets for use with individual jobs.
SAFETY INFORMATION:
Proper sizing of the generator is crucial to the success of any installation and requires a good working knowledge of
electricity and its characteristics, as well as the varying requirements of the electrical equipment comprising the load. When
analyzing the electrical load, consult the manufacturer’s nameplate on each major appliance or piece of equipment to
determine its starting and running requirements in terms of watts, amps and voltage. When choosing the generator output
for commercial or industrial applications, select a rating that is approximately 20 to 25% higher than the peak load (for
example, if the load is about 40 kilowatts, select a 50 kilowatts genset). A higher rated generator will operate comfortably at
approximately 80% of its full capacity and will provide a margin of exibility if the load increases in the future.
For safety reasons, it is recommended that the backup power system be installed, serviced and repaired by a Generator
Authorized Service Dealer or a competent, qualied electrician or installation technician who is familiar with applicable
codes, standards and regulations.
It is essential to comply with all regulations established by the Occupational Safety & Health Administration (OSHA) and
strict adherence to all local, state and national codes is mandatory. Before selecting a generator, check for municipal
ordinances that may dictate requirements regarding placement of the unit (setback from building and/or lot line), electrical
wiring, gas piping, fuel storage (for liquid propane or diesel tanks), sound and exhaust emissions.
2
Table of Contents
Table 1 – Motor Load Reference .................................................................. 4
Table 2 – Non-Motor Load Reference .............................................................. 5
Table 3 – Surge Capability ...................................................................... 6
Table 4 – Natural Gas Installation and Fuel Pipe Sizing Natural Gas ....................................... 7
Table 5 – LP Vapor Installation and Fuel Pipe Sizing LP Vapor ............................................ 8
Table 6 – LP Vapor (LPV) Tank Sizing and Table 7 – Generator Fuel Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
UPS – Generator Compatibility .................................................................. 10
Typical Generator/Transfer Switch Combinations .................................................. 11–12
NEC 700, 701, 702 Comparison ................................................................. 13
Electrical Formulas, Weights and Measures ......................................................... 14
Selected Circuit Load Calculator .............................................15–16, 19–20, 23–24, 27–28
System Capacity – Load Calculator ...........................................17–18, 21–22, 25–26, 29–30
3
TABLE 1
Motor Load Reference
AC & Heat Pumps Running Load Starting Load
Description Hp Running kWAmps
@ 240V
1Ø
1 Ton
(12,000 BTU)
2 Ton
(24,000 BTU)
3 Ton
(36,000 BTU)
4 Ton
(48,000 BTU)
5 Ton
(60,000 BTU)
7.5 Ton
(85,000 BTU)
10 Ton*
(120,000 BTU)
10 Ton
(120,000 BTU)
15 Ton*
(180,000 BTU)
15 Ton
(180,000 BTU)
20 Ton*
(240,000 BTU)
20 Ton
(240,000 BTU)
25 Ton
(300,000 BTU)
30 Ton*
(360,000 BTU)
30 Ton
(360,000 BTU)
40 Ton*
(480,000 BTU)
40 Ton
(480,000 BTU)
50 Ton*
(480,000 BTU)
50 Ton
(480,000 BTU)
* For Multiple motor configurations, sequence starting is assumed.
1 1 5 3 3 1 33 22 19 10
2 2 10 7 6 3 67 44 38 19
3 3 15 10 8 4 100 67 58 29
4 4 20 13 11 6 117 78 67 34
5 5 25 16 14 7 145 97 84 42
7.5 7.5 37 24 21 11 219 146 126 63
5 Hp (x2) 10 49 33 28 14 145 97 84 42
10 Hp 10 49 33 28 14 250 167 144 72
7.5 Hp (x2) 15 74 49 42 21 219 146 126 63
15 Hp 15 74 49 42 21 375 250 217 108
10 Hp (x2) 20 98 65 57 28 250 167 144 72
20 Hp 20 n/a 65 57 28 500 333 289 144
25 25 n/a 82 71 35 625 416 361 180
15 Hp (x2) 30 n/a 98 85 42 375 250 217 108
30 Hp 30 n/a 98 85 42 750 500 433 217
20 Hp (x2) 40 n/a 131 113 57 500 333 289 144
40 Hp 40 n/a 131 113 57 1000 666 577 289
25 Hp (x2) 50 n/a 163 142 71 625 416 361 180
50 Hp 50 n/a 163 142 71 1250 833 722 361
General Residential Running Load Starting Load
Description Hp Running kW Amps @
Refrigerator pump,
sump, furnace, garage
opener
Freezer, washer, septic
grinder
General 1 Hp 1 1 9.8 4.9 3 50 25
Well & septic
lift pump
4
0.5 0.5 4.9 2.5 1.5 25 13
0.75 0.75 7.4 3.7 2.3 38 19
2 2 19.6 9.8 6 100 50
Amps @
208V 3Ø
Amps
@ 240V
3Ø
120V 1Ø
Amps @
480V 3Ø
Air Conditioning
1 hp per 1 ton
1 ton = 12,000 BTUs
4.9 Amps @
240V 1Ø
LR Amps
@ 240V 1Ø
LR Amps
@ 208V 3Ø
Starting kW LR Amps @
LR Amps
@ 240V 3Ø
120V 1Ø
LR Amps
@ 480V
3Ø
LR Amps @
240V 1Ø
TABLE 2
Non-Motor Load Reference
Residential
Running Load*
Amps at
Description kW
Electric heat per 1000 ft
2
Heat pump elements per 1000 ft
2
12 n/a 50
7 n/a 29
120V 1ø
Dryer 5.5 n/a 23
Hot tub 10 n/a 50
Range oven/Stove top per burner 8 n/a 30
Electric hot water 4.5 n/a 19
General lighting and receptacles
per 1000 ft
2
3 24.9 n/a
Blow dryer 1.25 10.4 n/a
Dishwasher 1.5 12.5 n/a
Microwave 1 8.3 n/a
Toasters 1 8.3 n/a
Home Entertainment Center 1 8.3 n/a
Computer 1 8.3 n/a
Kitchen 1.5 12.5 n/a
Laundry 1.5 12.5 n/a
Amps at
240V 1ø
*Always check data plate for actual running amps.
Commercial
Please refer to equipment data plate and/or billing history for commercial details.
5
TABLE 3
Surge Capability
Honeywell Generators (Operating at less than 3600 RPM)
Rated Output
Maximum Surge Capability
(Running Amps)
Size (kW) 240V 1Ø 208V 3Ø 240V 3Ø 480V 3Ø 240V 1Ø 208V 3Ø 240V 3Ø 480V 3Ø
25 113 87 75 n/a 265 221 192 n/a
35 146 121 105 52 225 210 182 87
45 188 156 135 68 321 269 233 112
70 292 243 210 105 550 471 408 201
100 417 347 300 150 738 452 426 261
130 542 451 390 195 1088 885 767 419
Honeywell Generators (Operating at 3600 RPM)
Rated Output
(Running Amps)
Size (kW) 240V 1Ø 208V 3Ø 240V 3Ø 480V 3Ø 240V 1Ø 208V 3Ø 240V 3Ø 480V 3Ø
11 42 n/a n/a n/a 92 n/a n/a n/a
15 71 n/a n/a n/a 130 n/a n/a n/a
20 83 n/a n/a n/a 185 n/a n/a n/a
60 250 208 180 90 350 251 218 136
70 292 243 210 105 550 471 408 201
80 333 278 240 120 550 466 404 212
150 625 520 451 226 1214 1334 1156 624
Maximum Surge Capability
Note: All nominal ratings based upon LP fuel. Refer to specication sheet for
NG ratings and deration adjustments for ambient temperature and altitude.
6
NATURAL GAS INSTALLATION
BTU and
Pressure Decal
Flex Fuel Line Safety Shut-Off
with Pressure Port
Check Distance with
Gas Provider
Size Meter for Generator Load
Plus ALL Appliances
Size gas pipe with Generator Sizing Guide or to local codes.
Fuel Pipe Sizing Natural Gas
TABLE 4A
kW 0.75" 1" 1.25" 1.5" 2" 2.5" 3"
11 20 85 370 800
15 40 190 425
20 20 130 305 945
25 85 203 552
35 35 95 370 915
45 50 230 585
60 25 145 390 1185
70 5 75 225 710
80 65 195 630
100 40 140 460
130 50 215
150 30 150
Natural Gas 5" to 7" of Water Column
(Table values are maximum pipe run in feet.)
Pipe Size (in)
For Underground Installations Verify
Piping System for Code Compliance
TABLE 4B
Natural Gas 3.5" to 5"
of Water Column
(Table values are maximum
pipe run in feet.)
Pipe Size (in)
kW 0.75" 1" 1.25" 1.5"
11 30 125 200
15–17 10 60 125
20 10 60 125
Natural Gas
1 cubic foot = 1,000 BTU
1 therm = 100,000 BTU
Gas consumption = 13,000-16,000 BTU per kW/hr
Pressure
1 inch mercury = 13.61 inches water column
1 inch Water Column = 0.036 psi
3.5–7 inches water column = 0.126 psi to 0.252 psi
Note:
– Pipe sizing is based on 0.5" H
– Sizing includes a nominal number of elbows and tees.
– Please verify adequate service and meter sizing.
– Tables based on black pipe.
O pressure drop.
2
7
LP VAPOR INSTALLATION
BTU and
Pressure Decal
Check Distance with
Regulator Manufacturer
Check Distance
with LP Provider
Size Tank Large Enough to Provide
Required BTU's for Generator and ALL
Connected Appliance Loads.
Be Sure to Correct for MIWR (See Table 6)
Primary Regulator
Per LP Provider
Flex Fuel Line
Size gas pipe from secondary regulator with Generator Sizing
Guide or to local codes.
TABLE 5
Fuel Pipe Sizing LP Vapor
Safety Shut-Off
with Pressure Port
LP Vapor (LPV) 11" to 14" of Water Column
(Table values are maximum pipe run in feet.)
Pipe Size (in)
kW 0.75" 1" 1.25" 1.5" 2" 2.5" 3"
11 70 255 1000
15 25 130 540
20 15 115 480
25 55 260 575
35 20 125 290 1030
45 70 165 620
60 45 115 445 1095
70 20 60 260 660
80 15 50 230 590
100 30 165 430 1305
130 70 205 660
150 45 150 490
High Pressure Pipe
Secondary Regulator
Vented 5' from Generator
LP
LPG: 8.55 ft
LPG: 36.3 ft3 = 1 gal.
Pressure
1 inch mercury = 13.61 inches water column
1 inch Water Column = 0.036 psi
11–14 inches water column = 0.396 psi to 0.50 psi
3
/lb., 4.24 lbs./gal., 2500 btu/ft
Sized per LP Provider
3
8
Note:
– Pipe sizing is based on 0.5" H
– Sizing includes a nominal number
of elbows and tees.
– Please verify adequate service and meter sizing.
– Tables based on black pipe.
O pressure drop.
2
TABLE 6
LP VAPOR (LPV) TANK SIZING
Vapor Withdrawal
Tank Capacity
Total (Gal.)
120 72 40
150 90 40
250 150 40
325 195 40
500 300 40
Tank Capacity
Useable (Gal.)
Minimum Temp
(°F)
20
0
20
0
20
0
20
0
20
0
Tank Capacity (btu/hr.) Length
(Inches)
246,240
164,160
82,080
293,760
195,840
97,920
507,600
338,400
169,200
642,600
428,400
214,200
792,540
528,360
264,180
57 24 33
68 24 33
94 30 39
119 30 39
119 37 46
Diameter
(Inches)
Overall Ht.
(Inches)
Gas Required for Common Appliances
APPLIANCE Approximate Input
Warm Air Furnace
Single Family
Multifamily, per unit
Hydronic Boiler, Space Heating
Single Family
Multifamily, per unit
Hydronic Boiler, Space and Water Heating
Single Family
Multifamily, per unit
Range, Free Standing, Domestic
Built-In Oven or Broiler Unit, Domestic
Built-ln Top Unit, Domestic
Note: Tank BTU capacity and generator run times based upon maintaining a
minimum tank fuel level of 20%. Tanks are typically lled to 80% full.
Note: Typical fuel consumption based on a generator 100% loaded.
BTU / Hr
60,000–120,000
40,000–60,000
80,000–140,000
50,000–80,000
100,000–200,000
50,000–100,000
50,000–90,000
14,000–16,000
40,000–85,000
TABLE 7
Generator
kW Rating
LP Nat. Gas LP Vapor Nat. Gas LP Vapor Nat. Gas
8 7 129,000 121,000 79,000 78,000
11 10 175,000 195,000 107,000 124,000
13 13 268,000 255,000 149,000 157,000
14 14 279,000 279,000 168,000 177,000
15 15 260,000 296,000 166,000 185,000
17 16 325,000 312,000 181,000 193,000
20 18 350,000 308,000 189,000 205,000
22 22 313,000 316,000 188,000 190,000
25 25 430,000 430,000 298,000 297,000
27 25 356,000 359,000 195,000 197,000
30 30 493,000 492,000 320,000 320,000
36 35 500,000 503,000 280,000 282,000
45 45 725,000 730,000 378,000 380,000
48 48 755,000 756,000 393,000 392,000
60 60 818,000 862,000 458,000 483,000
70 67 1,028,000 1,020,000 503,000 500,000
80 80 1,163,000 1,154,000 603,000 600,000
100 94 1,268,000 1,260,000 718,000 713,000
130 122 1,798,000 1,786,000 933,000 927,000
150 142 2,075,000 2,061,000 1,078,000 1,070,000
GENERATOR FUEL CONSUMPTION
Fuel Consumption
at 100% BTU/HR
Fuel Consumption
at 50% BTU/HR
Operating Cost Per Hour
=
NG Therms/HR x Cost of NG Therm
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UPS - Generator Compatibility
Passive (also referenced as
standby or off-line) and
Line-Interactive
These technologies are most common
for personal workstations and point
of sale applications. They are typically
single phase equipment with size
ranges of 350 VA - 2000 VA for
passive and 500 VA to 5000 VA for
line-interactive.
Passive UPS’s are the simplest type.
Under normal conditions AC power
passes straight through to the UPS
load. When the input power supply
goes outside of specications, the
UPS transfers the load from input
power to the internal DC to AC power
inverter. Passive UPS’s do not correct
for voltage or frequency deviations
under “normal” operation.
Line-interactive is similar to the
passive technology except it has
circuitry that attempts to correct for
standard voltage deviations. Frequency
deviations under “normal” power
operation are not corrected.
Equipment Notes:
These devices tend to be electrically /
harmonically very noisy. A single small
UPS is not a signicant concern, but
applications with multiple UPS’s can
be problematic.
Passive UPS technology typically
has normal tolerances of 10-25% on
voltage and 3 Hertz on frequency.
Minuteman UPS input tolerance is
closer to 10-36%. If the input source
goes outside of these tolerances, the
UPS will switch onto the UPS battery
source. Some line-interactive units
may have frequency tolerances factory
set to 0.5 Hertz. These units will need
to have their frequency tolerance
increased to a minimum of 2 Hertz.
Minuteman UPS products are close to
5 Hertz and not 0.5 Hertz.
Generator Sizing Recommendation:
Limit the total UPS loading to 15% - 20%
of the generator capacity.
Double-Conversion
This technology is most common
for critical load applications. Doubleconversion UPS’s constantly rectify
AC to DC and then invert the DC back
into AC. This conguration results in
an output that corrects for voltage and
frequency deviations.
There are single and three phase
models covering small through large
applications. Most UPS applications
larger than 5000 VA use double
conversion technology. This approach
is also the preferred technology for
generator applications.
Equipment Notes:
Double-conversion UPS’s that are
single phase or unltered three phase
models tend to create a signicant
level of electrical/ harmonic noise.
This is illustrated by harmonic current
distortions that are greater than 35%.
Minuteman UPS products could
have current distortion of 8%. When
three phase models are supplied with
harmonic lters (current distortion less
than 10%), this concern is no longer
an issue.
Generator Sizing Recommendation:
Single phase models: limit the total
UPS loading to 25% of the generator
capacity. Single phase Minuteman
UPS models: limit the total UPS
loading to 50% of the generator
capacity. Three phase models without
lters (current distortion > 30%):
limit the UPS loading to 35% of the
generator capacity. Three phase
models with lters (current distortion <
10%): limit the UPS loading to 80% of
the generator capacity.
UPS Information
2 x kVA rating for a ltered system
3 – 5 x kVA rating for an unltered system
It is recommended you refer to the Honeywell UPS Generator Compatibility sheet
(Pg 10) and contact the manufacturer of the UPS system to assist in your installation.
Supplier(s) Passive (Standby) Line-Interactive Double-Conversion
Minuteman UPS Enspire Enterprise Plus Endeavor
APC Back-UPS Series Smart-UPS Series Symmetra Series
Liebert PowerSure PST & PSP PowerSure PSA & PSI UPStation & Nnity
Powerware 3000 series 5000 series 9000 series
Note: Ferrups and Delta-Conversion UPS technologies not included in discussion
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