Heat Exchangers

Heat exchangers transfer heat between two closed loops without mixing fluids. Hydronic systems use that separation to protect a boiler loop, feed a secondary loop, support radiant zones, and handle domestic hot water loads that need a dedicated heat transfer surface.

Series options span L-Line Series, Alfa Laval CB Series, Hydronic BPX Series, Low Pressure Series, and GNS Series, with brands like Alfa Laval, Bell & Gossett, Kelvion, and AIC Heat Exchangers.

Many brazed plate heat exchangers in this category call out capacity and application right in the name, which makes early comparisons faster. Examples range from 60,000 BTU/Hr up through 900,000 BTU/Hr, with some models labeled for Domestic Water or Radiant Heat. Plate count also shows up frequently, including examples like 18 plates, 24 plates, 34 plates, and 38 plates.

How to narrow the right heat exchanger fast

Start with the application label, then confirm capacity.

Domestic water and radiant loops tend to behave differently in the real world. Models labeled for Domestic Water or Radiant Heat help narrow the shortlist before comparing plate count and connections.

Use BTU/Hr as the first-pass sorter, then use plate count to fine tune.

BTU/Hr gets the sizing conversation pointed in the right direction. Plate count helps step up or down in capacity while staying within a series.

Lock in connection constraints early.

Some listings call out thread size and flow in the title, including examples like 2" thread and 100 GPM. Connection and piping constraints usually eliminate more options than price.

Keep the supporting hardware in the same plan.

A heat exchanger needs stable flow, clean air removal, and pressure control to avoid constant tinkering. Circulator pumps live at Circulator Pumps. Air eliminators live at Air Eliminators. Hydronic expansion tanks live at Hydronic Expansion Tanks

Common pairings for typical installs

Boiler side and system piping

Standard gas boilers sit at Gas Boilers. Zone valves for multi-zone control sit at Zone valves.

Domestic hot water support

Indirect water heaters sit at Indirect water heaters. Thermostatic mixing valves sit at Thermostatic mixing valves.

Radiant system support

Radiant heat components sit at Radiant heat.

FAQs
What is a brazed plate heat exchanger used for in hydronic systems?

A brazed plate heat exchanger transfers heat between two loops without mixing fluids. That separation is commonly used for boiler loop protection, secondary loop separation, radiant circuits, and domestic hot water loads that need isolation.

Why do some heat exchangers list BTU/Hr in the product name?


BTU/Hr is a quick capacity cue that helps compare models without digging through every spec sheet first. It is a practical first filter before narrowing by plate count, connection type, and footprint.

What does plate count tell about a heat exchanger?

Plate count is a common comparison point within a series. Higher plate counts often track with higher capacity options, while staying within the same fitting and general form factor.

Why does connection size matter so much?

Connection size drives the piping plan. It also impacts head loss and flow strategy. A model that does not match the piping reality can turn a simple swap into a repipe.

What is the point of a “low pressure” heat exchanger?

Low pressure naming is typically used to help flag options designed to keep pressure drop lower at a given flow. That can matter on higher flow applications or when pump head is limited.

What else typically gets added with a heat exchanger install?

Common companion categories are circulator pumps, air eliminators, and expansion tanks, plus zoning hardware when the system uses multiple loops or zones.
Circulator Pumps
Air eliminators
Expansion tanks
Zone Valves