For homeowners and professionals alike, a power washer is more than just a convenience — it’s a time-saving, efficiency-boosting tool that can turn tough cleaning jobs into quick tasks. But while many consumer models struggle with durability and true cleaning power, the Simpson ALH3425 Gas Pressure Washer bridges the gap between commercial strength and portable design.
Powered by the Honda GX200 engine, delivering 3600 PSI at 2.5 GPM, and equipped with a 35-foot MorFlex hose and rugged aluminum frame, this machine is designed for contractors, maintenance crews, and serious DIYers who want professional-grade results without spending thousands.
- Professional Performance: Easy-to-assemble and easy-to-start with its HONDA GX200 commercial series engine, the Aluminum Series power washer is great for contractors who specialize in deck cleaning, wood restoration, and all other professional services
Simpson ALH3425 – Quick Specs
| Feature | Specification |
|---|---|
| Model | Simpson ALH3425 |
| PSI / GPM | 3600 PSI / 2.5 GPM |
| Engine | Honda GX200 (commercial series) |
| Pump | AAA Industrial Triplex Plunger Pump |
| Frame | Aircraft-grade aluminum |
| Hose | 35 ft MorFlex, non-marring, kink & abrasion resistant |
| Wheels | 10” pneumatic wheels |
| Nozzles | 5 quick-connect spray tips (0°, 15°, 25°, 40°, soap) |
| Weight | ~80 lbs |
| Warranty | Engine: 3 years; Pump: 5 years; Frame: 10 years |
| Best For | Driveways, decks, siding, fences, commercial jobs |
Key Features of the Simpson ALH3425
1. Honda GX200 Engine
The standout feature of the ALH3425 is its reliable Honda GX200 engine. Known in the industry for durability, easy starting, and long lifespan, the GX200 provides consistent power under heavy loads. This engine is used in countless commercial tools, giving you confidence in its reliability.
2. 3600 PSI / 2.5 GPM Cleaning Power
At 3600 PSI and 2.5 gallons per minute, this washer delivers the perfect combination of pressure and water flow. It’s strong enough for concrete driveways, siding, decks, brick, fences, and heavy equipment, yet balanced so you don’t blast surfaces into damage.
3. AAA Triplex Pump
The AAA industrial triplex plunger pump is more durable than axial cam pumps found on consumer models. It provides longer life, higher efficiency, and easier maintenance, making it suitable for commercial-level usage.
4. 35-Foot MorFlex Hose
The included hose is:
- 35 feet long – giving you plenty of reach without moving the unit constantly.
- Non-marring – won’t leave marks on surfaces.
- Kink & abrasion resistant – durable enough for tough jobs.
5. Aircraft-Grade Aluminum Frame
Lightweight yet durable, the aluminum frame is rust-resistant and designed for heavy-duty work. Combined with 10” pneumatic wheels, the ALH3425 is easy to maneuver across uneven surfaces.
6. Quick-Connect Nozzles (5 included)
You get a full set of nozzles for every job:
- 0° (Red): Maximum pressure for stubborn stains.
- 15° (Yellow): Stripping paint, heavy dirt.
- 25° (Green): General-purpose cleaning.
- 40° (White): Light cleaning, delicate surfaces.
- Soap Nozzle (Black): Apply detergents.
7. Commercial Warranty Coverage
The warranty is strong:
- Engine: 3 years
- Pump: 5 years
- Frame: 10 years
This coverage shows Simpson’s confidence in the ALH3425’s build quality.
Performance Review
Starting & Ease of Use
Thanks to the Honda GX200, starting is quick and reliable. The recoil system is smooth, and the engine settles into a steady idle.
Cleaning Power in Action
- Driveways & Concrete: Removes oil stains, mold, and grime easily.
- Wood Decks & Fences: With the 25° or 40° nozzle, it cleans without gouging wood.
- Vehicles & Equipment: The soap nozzle + lower pressure nozzles are safe for cars, trucks, tractors, and trailers.
- Siding & Brick: Effective against mildew and dirt, though care is needed at full PSI.
Hose & Maneuverability
The 35 ft hose eliminates constant repositioning, while the 10” pneumatic wheels handle grass, gravel, and uneven driveways with ease. The machine weighs around 80 lbs but feels lighter thanks to the well-balanced frame.
Durability
The triplex pump and Honda GX200 engine combination makes the ALH3425 a long-term investment. Unlike budget washers, this isn’t a “replace every 2 years” tool — it’s designed for years of service.
Pros and Cons
✅ Pros
- Honda GX200 engine = reliable, durable, powerful
- 3600 PSI / 2.5 GPM = commercial-grade cleaning
- AAA triplex pump = long-lasting, efficient
- 35 ft MorFlex hose included
- Lightweight aluminum frame
- Pneumatic wheels for portability
- 5 quick-connect nozzles
- Strong warranty (engine, pump, frame)
❌ Cons
- Louder than electric models
- Requires regular maintenance (oil changes, pump care)
- Heavier than entry-level gas washers (~80 lbs)
- No onboard soap tank (requires siphon)
- Price is higher than residential models
Simpson ALH3425 vs Competitors
| Feature | Simpson ALH3425 | Simpson MSH3125 (3200 PSI) | Generac 8874 (2900 PSI) |
|---|---|---|---|
| Engine | Honda GX200 | Honda GC190 | Generac OHV |
| Pressure / Flow | 3600 PSI / 2.5 GPM | 3200 PSI / 2.5 GPM | 2900 PSI / 2.4 GPM |
| Pump | AAA Triplex | Axial Cam | Axial Cam |
| Hose | 35 ft MorFlex | 25 ft | 25 ft |
| Frame | Aluminum | Steel | Steel |
| Weight | ~80 lbs | ~60 lbs | ~65 lbs |
| Best For | Contractors, commercial jobs | Homeowners, heavy residential | Residential |
The ALH3425 stands out as a true commercial-grade option, while the MSH3125 and Generac 8874 are more for homeowners.
Who Should Buy the Simpson ALH3425?
This pressure washer is perfect for:
- Contractors and professionals – maintenance crews, painters, cleaners.
- Property owners – with large driveways, decks, or commercial buildings.
- Farmers and mechanics – for tractors, trailers, and equipment cleaning.
- DIYers – who want professional results at home.
Not ideal if:
- You only need light-duty cleaning (an electric unit will do).
- You want quiet operation (gas engines are loud).
- You lack storage space (80 lbs with frame and wheels takes room).
Buying Guide: Choosing a Commercial Gas Pressure Washer
- Engine Quality: Honda GX200 > most competitors.
- PSI & GPM Balance: 3600 PSI / 2.5 GPM is perfect for versatility.
- Pump Type: Triplex pumps last longer than axial cam.
- Frame Material: Aluminum = lighter and rust-resistant.
- Hose Length: 35 ft is superior for reach.
- Warranty: Long-term protection for engine, pump, and frame.
Final Verdict: Is the Simpson ALH3425 Worth It?
The Simpson ALH3425 Gas Pressure Washer is one of the best commercial-grade portable pressure washers in 2025. With Honda GX200 power, 3600 PSI at 2.5 GPM, a 35-foot hose, and a rugged aluminum frame, it’s built for professionals and homeowners who demand serious performance.
It costs more than residential washers, but the durability, warranty, and cleaning power make it a smart long-term investment. If you need a dependable machine for heavy-duty cleaning, the ALH3425 is hard to beat.
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FAQs About the Simpson ALH3425
Q1. Can it clean concrete driveways?
Yes, at 3600 PSI it removes stains, dirt, and mildew easily.
Q2. Is it safe for cars?
Yes, when using the 40° or soap nozzle with proper distance.
Q3. Does it include a soap tank?
No, but it supports detergent siphoning.
Q4. How heavy is it?
Around 80 lbs, with 10” pneumatic wheels for portability.
Q5. What’s the warranty?
Engine: 3 years, Pump: 5 years, Frame: 10 years.
Q6. Can it handle daily commercial use?
Yes, thanks to the Honda GX200 engine and AAA triplex pump.
Q7. What hose does it include?
A 35 ft MorFlex hose that is kink- and abrasion-resistant.
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