When Priddy Chimney Solutions was brought in to work on a large residential project in Annapolis, Maryland, the scope made clear from the start that this wasn’t going to be a standard chimney fan installation. The home featured three separate fireplace systems: two Isokern Magnum and Maximus linear fireplaces and a Heat N Glo direct vent gas fireplace. Each required its own venting solution and, in the case of the two Isokern systems, dedicated mechanical inline fan installations to ensure proper draft performance.
The project is worth walking through in detail because it illustrates something our team encounters regularly on larger homes. The bigger the fireplace system, the more critical the fan and venting specification becomes, and the more consequences follow from getting it wrong.
What Made This Project Technically Complex
Isokern fireplaces are modular volcanic pumice masonry systems that can be built at large scale. The 60″ Magnum in the great room of this home has a firebox finished width of 55 inches, a depth of 22 inches, and a back wall width of 46.5 inches. The 48″ Maximus in the master bedroom, while slightly smaller, runs a 44.5-inch finished width. These are serious combustion appliances that move a significant volume of air and gas when in operation.
At that scale, relying on natural draft alone introduces real risk. Larger fireboxes produce more combustion volume, and in a modern, tightly constructed or well-insulated home, natural draft can be inconsistent. This is particularly true when the system is competing with HVAC systems, kitchen exhausts, or the negative pressure created by the home’s sealed envelope. The solution for both Isokern systems was the Isokern X-Ventiso Mechanical Inline Fan, installed at the flue termination and wired to interior controls.
The third fireplace, a Heat N Glo Mezzo 36″ Direct Vent unit installed in the home’s office, used a different approach entirely. Direct vent gas fireplaces draw combustion air from outside through a sealed two-pipe system rather than from the room, which means they don’t compete with the home’s air pressure for draft. The venting for this unit ran vertically through the ceiling and into an existing brick chase, using a DVP Series termination with inline power vent horizontal termination.
Each system required its own venting specification, its own fan solution, and its own liner run.
The Isokern X-Ventiso Inline Fan: What It Does and Why It Was Specified Here
The Isokern X-Ventiso Mechanical Inline Fan creates controlled mechanical draft by drawing combustion gases up through the flue and expelling them at the termination. Unlike a standard chimney cap, the fan actively manages airflow rather than passively allowing it. This matters significantly on large-format fireplace systems where natural draft alone may be insufficient or inconsistent.
For the Annapolis project, two separate X-Ventiso fan systems were specified: one for the 48″ Maximus in the master bedroom and two units for the 60″ Magnum system in the great room. The great room installation used two fans given the volume of the 60″ firebox and the length of the venting run.
Each system was installed using the Isokern Eco Steel+ Insulated Vent System, a locking-tab designed stainless steel pipe system with a 12 5/8″ inner diameter and 15 5/8″ outer diameter, rated for any solid fuel Isokern application. The insulated construction is important for a specific reason: keeping the liner wall warm reduces condensation and helps the system reach and maintain proper draft temperature faster. The master bedroom system used 25 to 30 feet of pipe with two 45-degree offsets. The great room system required 35 feet of pipe per flue with additional offset components to navigate the venting path through the home’s structure.
The liner photos from this project show the rigid stainless sections running through the chase space with proper support straps. That kind of installation detail keeps the liner positioned correctly over a 25 to 35-foot run and prevents movement over time.
What the Installation Looked Like
The fan and venting work on this project involved multiple days of work per fireplace system. The master bedroom Maximus was a four-day project, and the great room Magnum ran six to seven days given its scale and the dual-flue requirement.
Looking at the photos from this project, what stands out is the scale of the brick enclosure surrounding these fireplaces. These aren’t standard residential fireboxes set into a wall. They are full masonry structures with open-top enclosures visible from the roof, more reminiscent of a commercial kitchen exhaust setup than a typical residential chimney. The fan and cap assemblies installed at the liner termination inside these enclosures are substantial units mounted on the stainless liner sections, with the wiring for the inline fans running to interior control switches.
The gas burner work on the great room system used a Grand Canyon 48″ JUMBO Arizona Weathered Oak vented gas log set with a separate 48″ front view burner. This two-component system delivers the visual scale appropriate to a 60-inch firebox. The 36″ linear burner in the master bedroom used driftwood media with Terra Copper glass, which complements the Maximus’s clean-face linear aesthetic.
Working With Builders and Contractors on Large Residential Projects
This Annapolis project was completed for a general contractor managing a significant residential build, which reflects one area of Priddy’s work that differs from a standard homeowner service call. When builders are specifying fireplace and chimney systems for high-end residential construction, the coordination requirements are different. The gas line and electrical supply are often contractor-provided, the boom lift access for roof work is coordinated through the build schedule, and the chimney and fireplace work needs to sequence correctly with other trades.
Our team at Priddy Chimney Solutions is experienced in working within contractor-managed project timelines. We coordinate our work to the manufacturer’s installation specifications, and communicate clearly about what we need from other trades: gas line access at the firebox, electrical supply for fan switches and attic boxes, and roof access coordination. This keeps the project moving without delays.
If you’re a builder or contractor working on a project that includes Isokern, Heat N Glo, or other large-format fireplace systems in Maryland, Virginia, or DC, Priddy can work directly with your project team. To learn more about our support for trades, visit our trades resource page or reach out at 301-530-4262.
What This Project Demonstrates About Chimney Fan Specification
The Annapolis project illustrates a few principles that apply across chimney fan installations of any scale.
- Fan sizing and selection must match the system. The X-Ventiso fans specified here are rated for the Isokern Magnum and Maximus applications specifically, not generic chimney fans adapted to a large firebox. Using undersized fans on a 60-inch firebox, or fans not rated for the liner system, produces inconsistent draft and potential warranty issues with the firebox manufacturer.
- Liner specification is inseparable from fan specification. The Eco Steel+ insulated liner system used here isn’t just about meeting code. It’s about keeping the liner wall temperature high enough for consistent draft and minimizing condensation over a 25 to 35-foot run. The fan and the liner work together, and specifying them together from the start produces a better outcome than treating them as separate decisions.
- Venting path complexity drives project duration. The offset requirements, support strap placement, and coordination with the framing on a multi-story venting run are what make these projects take four to seven days per system rather than an afternoon. Homeowners and builders working on large fireplace installations should plan project timelines accordingly.
For more information on chimney fan installation and replacement, visit our chimney fan services page.
Schedule a Consultation for Your Fireplace or Chimney Fan Project
Whether you’re planning a new Isokern installation, troubleshooting draft problems on an existing large-format fireplace, or building a home that will include multiple fireplace systems, Priddy Chimney Solutions has the experience to help you get the specification right from the start.
Our CSIA-certified technicians have been working on chimney fan installations, liner systems, and large masonry fireplace projects across Maryland, Northern Virginia, and Washington D.C. since 1982. We’re fully licensed and insured in Maryland (MHIC #154840) and DC (HIC #420224000019).
Call us at 301-530-4262 or schedule an appointment online.
