At Krell Distributing, we are experts in both open and closed radiant heating systems, and can help you understand the difference. In an open radiant system, radiant floor heat is mixed with domestic hot water. This condition may create a hazardous situation, because the low water temperature (below 140 degrees) is conducive to bacteria growth in the tubing. It is best to keep the domestic water system separated from the heating system water. For information on safe potable hot water go to the Centers for Disease Control website at www.cdc.gov.
Play it safe. Keep the two systems separate
It is best to use the closed system concept when designing a radiant heating system. Aside from the bacteria potential, the closed system just works better. Closed system components are less expensive because an open system requires bronze or stainless steel pumps and fittings instead of cast iron. In an open system, oxygen is constantly being introduced into the system with incoming water, while in a closed system the original fill water, once vented of air, remains in the system for the life of the system.
WE DO NOT RECOMMEND OR SUPPORT OPEN-LOOP HEATING SYSTEMS
The temperature requirements for healthy domestic hot water and the low temperature needs of your radiant floor heating are very different. This opinion is based upon our experience along with the national, state, and university studies and warnings.
The federal Centers for Disease Control website (www.cdc.gov) reports that 8,000 to 18,000 people contract Legionnaires' disease each year, with the illness fatal in 5%-30% of the cases.
The CDC study recaps data documenting the presence of Legionella bacteria in residential water systems because of the water heaters being set below 140 degrees Fahrenheit in order to prevent scalding injuries. It's a perfect habitat for growth. Because the bacterium enjoys warm water environments, it's a potential problem in hot water distribution systems.
Now you know the difference between open and closed radiant heating systems, but feel free to contact us with any questions. We would be happy to help you with a closed system using a boiler designed specifically for radiant floor heating. We carry radiant heating supplies to help you in your project. As always, we provide continued technical support. Contact us today to get started on your project.
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