What is the most common heat source for a radiant heating system?
The most common heat source is a hydronic boiler. Different from a domestic water heater, it has relays, transformers, aqua-stats, gas ignition systems, safety controls and is designed to accommodate increased output and flow rates often required by radiant panel systems. A typical residential water heater holds 40 gallons of water and has an output rating of approximately 40,000 BTU. A typical residential copper boiler will hold 1-2 gallons of water and output 100,000-225,000 BTU. Cast iron boilers usually hold more water, between 5-20 gallons total. Typically less storage means less standby loss and high output means faster temperature generation. Hydronic boilers are designed for the application where most water heaters are not. Some water heaters can be used for small radiant heating applications.
