Blue Star Power Systems · PSI Small Gaseous (20-100 kW)

Blue Star PS25-01

20 kW standby · Natural Gas / LPG · Liquid-cooled

20 kW natural gas / LP standby generator from Blue Star Power Systems. PSI 2.4L four-cylinder naturally aspirated engine, Stamford S1L2-J41 alternator, DSE DCP7310 controller, 208-600V output.

Blue Star Power Systems Blue Star PS25-01 generator — specifications and details
Standby power
20 kW
Voltage options
120/240V, 120/208V, 240V, 277/480V, 347/600V
Frequency / Phase
60 Hz · 1/3-phase
Engine
PSI 2.4L · 2.4L
EPA / Emissions
EPA Stationary Spark Ignition
Alternator
Stamford S1L2-J41
CommercialResidentialProperty MgmtHospitalityGovernment
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Overview#

The Blue Star PS25-01 is a 20-kilowatt natural gas and LP standby generator powered by the PSI 2.4L — a four-cylinder, inline, naturally aspirated engine from Power Solutions International. Despite the "25" designation in the model number, the PS25-01 is rated at 20 kWe standby on both fuel types. It is the smallest model in Blue Star's PSI-engined stationary gaseous product line.

Blue Star Power Systems pairs the 2.4L engine with a Stamford S1L2-J41 alternator and DSE DCP7310 controller on a formed steel base. The OPU (open power unit) footprint is 66 × 36 × 45 in at 1,050 lbs — the most compact footprint in the gaseous line. Level 1, 2, and 3 enclosures are available with sound levels from 75 dBA (OPU) down to 62 dBA (Level 3) at full load.

PSI 2.4L Platform#

The PSI 2.4L is a compact four-cylinder inline engine running at a 9.5:1 compression ratio. At 20 kWe standby, it operates with significant headroom below the 46.5 hp (34.7 kWm) rated capacity. Fuel input at full standby load is 431 ft³/hr natural gas or 184 ft³/hr LP — numbers consistent with a lightly loaded platform. Exhaust temperature of 1,350°F is consistent across all Blue Star small gaseous units.

Deration Characteristics#

The PS25-01 derates 1% per 10°F above 77°F inlet air temperature and 3% per 1,000 ft above 1,200 ft altitude. For most commercial installations in temperate regions at moderate elevation, the full 20 kWe standby rating applies without adjustment. Sites above 1,200 ft should verify the derated output against the load requirement before finalizing the specification.

When to specify the PS25-01#

  • 15–20 kW natural gas or LP standby at commercial buildings, small offices, restaurants, or multi-family residential
  • Sites where the 66 × 36 in OPU footprint must fit a constrained mechanical room
  • Applications requiring 208-600V single- or three-phase output from a single generator
  • Projects where the same DSE DCP7310 controller platform as larger Blue Star gaseous units simplifies operator training and monitoring

Our service experience#

The PSI 2.4L is a compact platform that requires consistent attention to jacket water coolant condition — small coolant capacity (3.90 gallons total system) means degraded coolant affects the engine quickly. Annual load banking to full standby output is essential for a unit of this size; at 20 kWe it is easy to underload on typical commercial loads and accumulate unburned fuel deposits. Verify fuel inlet pressure at 11.0 in. W.C. at the generator during commissioning — low-pressure gas service is the most common source of performance complaints on small natural gas standby units.

Engineering specifications

Physical

Length
66 in
Width
36 in
Height
45 in
Dry weight
1,050 lb

Acoustic

Sound @ 7m, full load
75 dBA
Enclosure
Open

Fuel system & runtime

NG required pressure
11 in WC

Thermal & ventilation

Heat to coolant
91,200 BTU/hr
Heat radiated
20,580 BTU/hr
Exhaust flow
248 CFM
Exhaust temp
1350 °F
Combustion air
75 CFM
Ventilation air
4,752 CFM

Documents & downloads

Spec sheets & manuals

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Estimate runtime for the Blue Star PS25-01

Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.

Estimate runtime on this tank

Fuel demand at 75% load

210,000 BTU/hr≈ 210.0 cf/min @ 1,000 BTU/cf

On utility natural gas the runtime is generally unlimited provided the supply line and meter can deliver this BTU/hr at the engine's required inlet pressure (typically 5–14" WC residential, up to 5 psi commercial). Confirm against the OEM's published fuel-pressure spec.

Service intervals

Manufacturer-recommended intervals for the Blue Star PS25-01 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter
Every 250 hours or 12 months
Coolant change
Every 4000 hours
Air filter
Every 1000 hours
Spark plugs
Every 1500 hours
Major overhaul
≈ 15,000 hours
Load bank test
Every 12 months

Common failure modes

What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.

ComponentSymptomTypical hoursSeverity
Spark plugs / ignitionMisfire under load, hard starting1,500+minor
BatteryFailed to start during outage8,760+minor
Coolant systemOvertemp, coolant loss6,000+minor

Frequently Asked Questions

What engine does the PS25-01 use?
The PSI 2.4L — a four-cylinder, inline, naturally aspirated engine from Power Solutions International. The 2.4-liter displacement (144 cubic inches) produces 46.5 hp (34.7 kWm) at 1800 RPM standby. Despite the '25' in the model name, the PS25-01 is rated at 20 kWe standby on both natural gas and LP. Blue Star model numbering reflects the engine platform series rather than the exact kilowatt output. The PSI 2.4L is a compact, air-cooled-compatible design — here used in a liquid-cooled radiator configuration — well suited to applications where footprint is constrained.
What controller does the PS25-01 use?
The DSE DCP7310 Digital Control Panel, standard across Blue Star's current gaseous product line. It provides CAN Bus J1939 engine communication, digital metering, 8 programmable contact inputs, 10 contact outputs, RS-485 interface, and NFPA 110 Level 1 compatibility. The panel is cULus Listed and CE Approved with IP 65 ingress protection (with supplied gasket). A 12V battery system and battery charger are included standard. The PS25-01 is one of the smallest units to use the DCP7310 platform, which means the same software and monitoring tools apply across the full Blue Star gaseous lineup.
How does the PS25-01 compare to the PS40-01?
The PS25-01 (PSI 2.4L I-4, 20 kWe, 66 × 36 × 45 in, 1,050 lbs) and PS40-01 (PSI 4.3L V6, 40 kWe, 80 × 38 × 50 in, 1,575 lbs) represent two engine platform steps. The PS25-01 is 14 inches shorter and 525 lbs lighter — a meaningful difference in tight mechanical rooms. The PS40-01 doubles the output to 40 kWe on the same natural gas and LP fuel inputs. Both use the DSE DCP7310 controller and are available in 208-600V. If the load requirement is at or below 20 kWe and footprint is the primary constraint, the PS25-01 is the correct choice; otherwise the PS40-01 covers a wider range of commercial loads.
What are the fuel consumption rates for the PS25-01?
At 100% standby load, the PS25-01 consumes 431 ft³/hr of natural gas or 184 ft³/hr of LP. At 75% load: 339 ft³/hr NG or 140 ft³/hr LP. At 50% load: 262 ft³/hr NG or 104 ft³/hr LP. Required fuel inlet pressure is 11.0 in. W.C. from a 0.75-inch NPT connection. Heat rejected to the coolant circuit is 91,200 BTU/hr at full standby load; heat radiated to the room is 20,580 BTU/hr. Combustion air draw is 75 CFM; ventilation air requirement is 4,752 CFM for a radiator-cooled installation.

Compatible equipment

Transfer switches

More in the PSI Small Gaseous (20-100 kW)

20–100 kW natural gas and LP standby on PSI inline-four, V6, and V8 platforms — single and three-phase.

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