Pennco Silver 15C-9D 299,000 BTU Cast Iron Natural Gas Boiler

Warm Larger Homes With The Pennco Silver 15C‑9D 299,000 BTU Cast‑Iron Hot Water Gas Boiler

Need serious heating power for big homes or multi‑zone hydronic systems? The Pennco Silver 15C‑9D is a high‑capacity, cast‑iron, chimney‑vented hot water boiler built for dependable comfort and straightforward service. It delivers 84% AFUE efficiency, uses a smart Hydrolevel Fuel Smart control with built‑in low‑water cut‑off (LWCO), and pairs an integrated draft hood and motorized vent damper to help reduce standby losses—ideal for replacements where code‑compliant, natural‑draft venting is preferred.

• Brand: Pennco
• MPN: 15C‑9D (Silver 15C Series)
• Type: Gas‑Fired, Non‑Condensing Hot Water Boiler (Cast Iron, Category I, Chimney Vent)
• Fuel: Natural Gas (Propane version available — add “P” suffix)
• Input (NG): 299,000 BTU/h
• DOE Heating Capacity (NG): 252,000 BTU/h
• Net AHRI (Water, NG): 219,000 BTU/h
• AFUE: 84.0%
• Ignition: Intermittent electronic; Hydrolevel control with circulator management
• Venting: Integral draft diverter with automatic vent damper; 7" flue; chimney vent (Category I)
• Water Connections: 1‑1/4" NPT supply & return
• Gas Inlet: 1/2" NPT
• Water Content: 14.4 gallons
• Electrical: 120V AC, 60 Hz; <12 A (15 A circuit recommended)
• Dimensions (W × H × D): 30‑3/4" × 36‑3/8" × 26‑1/2"
• Certifications: AHRI certified
• Included: Hydrolevel Fuel Smart control with digital display & LWCO, motorized vent damper, insulated jacket, combo temperature/pressure gauge, 3/4" drain valve, 30 psi ASME relief valve
• Warranty: 10‑Year Limited heat exchanger (residential; see terms)

High Output For Larger Homes

With 299,000 BTU/h input and a 219,000 BTU/h Net AHRI (water) rating, the 15C‑9D delivers the capacity multi‑radiator homes need—when sized to your connected radiation and heat loss.

Fuel‑Saving Smart Control

The Hydrolevel Fuel Smart control features a digital display, built‑in low‑water cut‑off, and economy settings that target lower water temperatures when load is light—helping reduce fuel use without sacrificing comfort.

Low‑Profile Draft Diverter & Vent Damper

An integral draft hood and motorized vent damper lower overall height and help limit standby chimney losses. It’s a practical fit for low‑ceiling basements and straightforward, code‑compliant chimney venting.

Cast‑Iron Durability

A rugged cast‑iron heat exchanger with cast‑iron push nipples is pressure‑tested at the factory for long service life—well‑suited to baseboard and classic radiator systems.

Installer‑Friendly Connections

Standard 1‑1/4" supply/return tappings, a common 7" flue, and clear access to controls simplify change‑outs and annual service.

Want to learn more about this hydronic boiler? Read our blog on factors to consider before purchasing a hydronic boiler, pros and cons of hydronic boilers, and hydronic boiler recommendations.