Top Rated P-K DURATION® III Indirect Domestic Hot Water System
Indirect Domestic Hot Water System
P-K DURATION® III Indirect Domestic Hot Water System – Commercial & Industrial Mechanical Professionals
High-Efficiency, Low-Footprint Indirect DHW Solution Built for Mechanical & Plumbing Specifiers
If you’re specifying domestic hot water systems for commercial or industrial buildings—such as schools, hotels, healthcare, light industrial plants or stadiums—you need a solution that delivers rugged durability, minimal scale risk, compact footprint, seamless integration and low cost of ownership. The P‑K DURATION® III hits all those marks.
Built with a stainless steel double-wall brazed-plate heat exchanger, true air-gap protection, lead-free wetted materials and a footprint of less than 5.5 ft², this packaged water-to-water indirect system is designed to complement any condensing or hydronic heat source while simplifying installation, service and control.
Ready to spec or replace your commercial water-heating system?
Our NYC engineering team can provide:
- Free system review & load sizing
- Local jobsite delivery options
- Compliance consultation for NYC & Long Island codes
Call (718) 793-6900 or email us info@accardicompanies.com
Patterson-Kelley Duration Key Benefits
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Durable Construction
316/316L stainless double-wall brazed-plate heat exchanger with true air gap
Minimizes risk of cross-contamination, ensures potable water safety and vastly extends service life in high-cycle applications.
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Compact Footprint
Less than 5.5 ft² — approx. 15″ W × 50″ L
Allows placement through standard doors and fits in tight mechanical-rooms, penthouses or retrofit spaces with minimal rigging.
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Easy Installation
Fully packaged, four simple water connections and one power connection
Save on labour and rigging costs; ideal for side-by-side multiple unit installations.
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BAS Integration
Modbus RS-485, optional LONWORKS/BACnet or METASYS N2
Provides facility managers real-time insight and remote control for piping, pumps and system health.
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High Efficiency
Complements condensing boilers or any hydronic heat source
By pairing with an efficient boiler or hydronic loop you reduce fuel cost, improve water quality performance and extend equipment life.
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High Recovery Rates
0-85 GPM domestic demand, with ΔT 40°F–140°F
Supports higher load commercial demands from hotels, multi-unit residential, institutional and light industrial applications.
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Modular Scalability
Side-by-side installable units
Easily scale for large loads by adding parallel units rather than oversizing a single huge system—improves flexibility and serviceability.
Ready to streamline your hot-water system specification and installation?
- A no-obligation quote for your specific building load (GPM, ΔT, BTU)
- Access to detailed submittals, BIM/Revit files, AutoCAD drawings and installation guides
- Pre-installation planning support, including layout assistance and piping diagrams
- Local support via our experienced mechanical sales and service team
How It Works (Application Overview)
- Connect Your Heat Source Fully packaged indirect domestic hot water system connects a hydronic heat source (condensing boiler or other) via the P-K Duration III’s water-to-water brazed-plate heat exchanger into your domestic water loop.
- Heat Transfer & Scale Prevention The boiler side heats the exchanger; the domestic water passes through and delivers hot water to your distribution. The design ensures scale build-up is significantly reduced because the potable side is isolated via the double-wall brazed plate with an air gap.
- Quick Installation The packaged cabinet arrives ready-to-install: just make the boiler inlet/outlet, domestic inlet/outlet, attach power (single 110 V line) and you’re operational. For pumped versions, the unit includes integrated controls and circulation pump options.
- Reference Documentation See the detailed system diagram on page 3 of our technical documentation and installation photos for visual guidance.
Why Specifiers & Installers Choose It
By selecting the Duration III, you also simplify commissioning, piping design and retrofit planning because of its compact form, minimal connections and BAS integration. For multiple unit installations, you can locate units side-by-side, pipe in parallel and meet higher capacity demands without sacrificing footprint. Bundle with an Accardi Building Automation System to get real-time performance monitoring, reducing manual oversight for mechanical contractors in NYC who maintain multiple sites.
- Reduced Lifecycle Cost Lower maintenance and longer equipment life Fewer call-backs, less scale-related failure, easier access and serviceability.
- Future-Proof Controls Continuous monitoring and optimization BAS integration ensures your mechanical team can monitor and optimize hot water production and distribution continuously.
- Space-Constrained Installations Perfect for tight spaces Whether rooftop penthouses, multistory mechanical rooms or retrofit applications with tight access, the small footprint wins.
- Quick Turnaround Faster project completion Shorter on-site labour, fewer unknowns in rigging, streamlined commissioning—get mechanical schedules back on track.
- Scalability & Modularity Flexible deployment options You don’t need one oversize monster; you can deploy multiple units in your plan for staged build-out or redundancy.
- Trustworthy Brand & Documentation Complete design support Full suite of submittals, cut sheets, manuals and drawings available for design/BIM coordination. View Documentation
Navigating NYC Hot Water Projects? We're Here to Help.
Call (718) 793-6900 or email us info@accardicompanies.com
Why Choose Accardi Companies
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Local Expertise
Over 50 years serving mechanical and plumbing professionals across NYC & Long Island
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Manufacturer-Certified Support
We partner directly with Patterson-Kelley for technical, warranty, and service assistance
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Fast Turnaround
Local inventory and next-day delivery available on select models
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Specification Help
Access detailed submittals, CAD/Revit files, and engineering support
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On-Site Commissioning
Our service team ensures your P-K system starts up right the first time
Frequently Asked Questions (FAQs)
The instantaneous models (e.g., D3-30I, D3-50I, D3-80I) provide direct domestic water heating without a storage tank, ideal where boiler water is always available. The pumped and base versions include or require external pumps/expansion tanks and may include storage. The base version is designed to couple closely with a condensing boiler and a storage tank. See full specs in the Submittal.
The double-wall construction provides a true air gap between boiler side and domestic water side. That means any electrolytic contamination or corrosion products remain separated. The 316/316L stainless plate further resists scale build-up and corrosion. The result is longer service life, better efficiency retention and potable water code compliance.
The standard unit has a footprint of less than 5.5 ft² (approx. 15″ wide by 50″ long) for easy installation. It ships fully assembled, requiring four water connections (domestic inlet/outlet + boiler inlet/outlet) plus a single 110 V supply connection. Standard clearances include 6″ on some sides for ventilation and service.
Yes. The instantaneous version supports Modbus RS-485 communications directly. Optional protocol converters enable LONWORKS, BACnet or METASYS N2. The pumped versions are designed to operate seamlessly with the P-K NURO® control system. This enables remote monitoring and control of domestic hot water performance.
Because of the stainless,double-wall exchanger, minimal footprint, packaged delivery and BAS integration, maintenance downtime is reduced, service access simplified and long-term reliability improved. Less scale build-up means less efficiency loss and fewer repairs. For mechanical professionals, this translates to fewer service calls, less boiler/hydronic disruption and stronger lifecycle value. It also aligns with commercial building owner goals of uptime, reliability and controllable maintenance budgets.
Yes. It complies with NYC DEP backflow requirements and local plumbing code double-wall exchanger mandates. The lead-free stainless construction meets state health standards.
Absolutely. The Duration III connects easily to any hydronic system, making it ideal for retrofit projects throughout Manhattan and Nassau/Suffolk Counties.
Space is premium in city mechanical rooms. The Duration III fits through standard doorways and can be moved by two installers—saving crane or rigging costs.
Routine flushing and exchanger inspection are minimal due to its corrosion-resistant stainless design. Remote BAS monitoring further reduces on-site checks.
Accardi Companies maintains regional inventory and can typically fulfill orders within days depending on model availability. Request a quote for immediate availability and support.
For commercial mechanical contractors, engineers, and facility owners across New York City and Long Island, the P-K DURATION® III is more than a water heater—it’s a performance-driven, code-compliant system that saves time, space, and energy.
Accardi Companies is your local authorized Patterson-Kelley partner, ready to quote, supply, and service every job.
Complex NYC Installation? Our Team Specializes in Challenging Projects.
Call (718) 793-6900 or email us info@accardicompanies.com