W4443H — Bertolini Hot Water Duty Piston Pump | 4060 PSI | 4.3 GPM | 1″ Hollow Shaft

The W4443H is the hot water duty variant of Bertolini’s W4443 — a professional-grade triplex piston pump converted specifically for continuous hot water service up to 167°F (75°C). Engineered and manufactured by Idromeccanica Bertolini S.p.A. in Reggio Emilia, Italy, the W4443H shares the same forged brass head, bronze connecting rods, and WM Series architecture as the standard W4443, but is rebuilt with a complete hot water packing system — Sintek NBR U packing on the front seals and Inox U packing on the rear — to handle the thermal demands of continuous hot water operation. Recommended maximum operating pressure for the W4443H is 4060 PSI (280 bar) in hot water duty service.

What’s in the Box

• Fully Assembled W4443H Pump — Ships exactly as it leaves the WSHPWR service department. Bare pump configuration — hot water packing system installed, no unloader or injector included. Ready to mount.
• SAE J609-1″ Flange with 4-Bolt and Lock Washer Kit — Everything needed for a seamless, rattle-free installation directly to your engine. Grade hardware included — nothing to source separately.
• Vented Dipstick — Must be manually installed prior to field testing. Do not run the pump without it installed. Critical for preventing crankcase vapor buildup and protecting the seals during operation.

What Is the W4443H?

Standard triplex piston pumps — including the base W4443 — are designed for cold water duty with inlet temperatures up to 140°F (60°C). While that covers the vast majority of pressure washing applications, operations involving steam cleaning, hot water tank washing, industrial process cleaning, or recirculating hot water systems require a pump specifically built for sustained thermal exposure. Running hot water through a cold-duty pump accelerates seal degradation, causes premature packing failure, and can result in oil contamination and crankcase damage.

The W4443H addresses this directly. The conversion replaces the standard packing system with components rated for continuous hot water duty — allowing the pump to operate reliably at inlet temperatures up to 167°F (75°C) in sustained service. The recommended maximum operating pressure in hot water duty is 4060 PSI (280 bar) — a conservative rating that accounts for the additional thermal stress on internal components and extends the service life of the hot water packing system.

Hot Water Packing System

The W4443H conversion involves a complete packing replacement using two complementary seal materials selected for their thermal and chemical performance in hot water environments:

• Sintek NBR U Packing (Front Seals) — Nitrile butadiene rubber compound formulated for sustained hot water exposure. NBR maintains its elasticity and sealing geometry at elevated temperatures, resisting the thermal hardening and compression set that causes standard packing to leak prematurely in hot water applications. The U geometry is self-energizing under pressure, ensuring consistent contact force between the seal and plunger surface across the full operating temperature range.
• Inox U Packing (Rear Seals) — Stainless-compatible U packing engineered for the rear seal position where thermal cycling and chemical exposure are most concentrated. The Inox specification ensures compatibility with the WM Series stainless steel plunger guide components and maintains dimensional stability under repeated heat-and-cool cycles.

In addition to the packing replacement, O-ring materials throughout the W4443H are converted to compounds rated for hot water service — ensuring that every sealing surface in the pump is thermally appropriate for continuous duty operation at up to 167°F.

WM Series Architecture

Beyond the hot water conversion, the W4443H retains the full WM Series construction that makes the WMG platform one of the most durable compact piston pumps available. The forged brass head — increased wall thickness compared to the 3PG Series — is engineered specifically to withstand elevated operating temperatures without deformation. The bronze connecting rods, oversized premium bearings, tungsten carbide-coated plunger rods, and LowStressthread™ valve cap system are unchanged from the standard W4443.

Performance

What’s Inside the W4443H

• Forged Brass Head — Increased Wall Thickness — Engineered for higher operating temperatures and maximum rigidity under overpressure events.
• LowStressthread™ Valve Caps — Recessed O-ring design. Thread never contacts pressurized water. No Loctite required. Torque reduced by 40%.
• AISI 316 Stainless Check Valves — Mirror-finish, rapid-action for corrosion resistance and maximum fluid dynamic efficiency.
• Sintek NBR U Packing (Front) — Hot water duty nitrile butadiene rubber. Rated for continuous service up to 167°F (75°C).
• Inox U Packing (Rear) — Stainless-compatible rear seal for hot water and thermal cycling environments.
• Hot Water Duty O-Rings — Complete O-ring conversion to thermally rated compounds throughout.
• Tungsten Carbide-Coated Plunger Rods — Maximum wear resistance and volumetric efficiency.
• Bronze Connecting Rods (One-Piece) — Superior anti-friction performance and extended service life.
• Oversized Premium Bearings — Extended service life under heavy and continuous-duty conditions.
• Forged Steel Crankshaft — Extended Length — Maximum structural rigidity for solid pump-to-engine coupling.
• Die-Cast Aluminum Crankcase — Anti-corrosion alloy with diamond-tool machined plunger guide surfaces and enhanced cooling fins.
• Ventilated Oil Dipstick — Reduces risk of crankcase leakage due to vapor buildup during hot water operation.

Specifications

Applications

• Hot water pressure washing and steam-assist cleaning
• Industrial tank and vessel cleaning with hot water recirculation
• Food processing and sanitation washdown requiring elevated temperatures
• Fleet washing with hot water supply systems
• Agricultural equipment cleaning with hot water
• Industrial process cleaning at elevated temperatures

7-Year Warranty

The W4443H carries Bertolini’s industry-leading 7-year warranty on the pump, backed by over 100 years of Italian engineering. Hot water packing systems are subject to normal wear based on operating conditions and are not covered under the pump warranty. Contact WSHPWR for packing service and replacement guidance.