Intro to Boilers & Radiators w/ Moe Hirsch (Podcast)

In this episode, we talk with Moe about the world of hydronics. We discuss some fundamentals and talk about various boiler and radiator types.

Hydronic systems use water flow to move heat. We can compare these systems to railroads; the water is like a train carrying BTUs, and the BTUs get off the “train” at radiators. The pump moves water in a circle, though it moves that water pretty far. Boilers generally require a certain flow, and if a single circulator pump can't achieve that flow, we sometimes need to bring on a secondary circulator.

Radiators can either be radiant or convective. Baseboards are a major part of conventional convective hydronic designs. Fin-tube baseboards are made of copper piping with aluminum fins on them. Cast-iron baseboards also exist and are commonplace in older homes, but Moe avoids installing them on newer homes. When designing systems, you don't want radiators holding on to heat for a long time. Recessed radiators go into the wall and are typically cast-iron; exterior walls require insulation. Freestanding radiators are typical of old designs but are making a comeback. Kickspace heaters go under cabinets and are fan-forced systems.

Old boilers are generally cast-iron sectional boilers, and some are steel. Cast-iron boilers tend to be either dry-base (fire on the bottom) or wet-base boilers (power burner/gas-gun type). These old boilers also usually have tube bundles, especially wet-base boilers. Modern high-efficiency boilers are common nowadays. Combi boilers (combination boilers) also fall into the modern boiler category. Combi boilers act as on-demand water heaters.

Moe and Bryan also discuss:

• Relief valves and pressure margins
• Purging hydronic systems
• Hydraulic separation
• Delta T and what it means for hydronics
• Condensing boiler temperatures
• Radiant vs. conventional baseboard systems
• Hydronic towel warmers
• Humidity and airflow control
• Boiler runtimes
• Short cycling and modulation