For homeowners, contractors, and engineers
The complete resource for selecting and commissioning cast iron boilers
From a first residential replacement to a multi-zone commercial spec, the right cast iron boiler decision hinges on a handful of numbers — and exactly how you read them.
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What we'd buy
Our standout recommendations across every guide. Prices and availability change; we may earn a commission on purchases.
What you'll find here
Depth-first guides built for every stage of the project
Whether you're comparing entry-level units for a single-family home or cross-referencing IOM data for a premium commercial installation, every guide here starts approachable and goes as deep as you need.
Boiler Selection & Sizing
AFUE ratings, BTU load calculations, and honest comparisons across the Burnham, Weil-McLain, Slant/Fin, and Peerless lineups — from a $1,500 residential replacement to a $20,000 commercial spec. We cover what installer interviews and spec sheets reveal so you can walk into a purchasing decision with a clear shortlist.
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Hydronic System Components
Expansion tanks, circulator pumps, zone valves, air separators, fill valves, and pressure relief — the supporting hardware that determines whether a correctly sized boiler actually performs correctly in the field. Guides here cover sizing criteria, compatibility flags, and what experienced installers consistently flag as the parts worth spending up on.
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Heat Distribution & Zones
Baseboard radiators, radiant floor panels, kickspace heaters, unit heaters, and PEX manifold configurations — how heat gets from the boiler to the room, and how to match your distribution system to the boiler you've chosen. Covers both retrofit scenarios and new-zone additions to existing hydronic systems.
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