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Save Up to 15% on Energy with EndoTherm™ Additive for Hydronic Heating Systems

EndoTherm™ is an eco-friendly additive that can be used in any hydronic heating system to reduce energy costs by up to 15 percent. EndoTherm does this by significantly reducing the surface tension of water within the system. When surface tension is reduced, water heats up faster, heat transfer is enhanced, and the overall efficiency of the heating system is improved.

How EndoTherm Works

The internal surface of a hydronic heating system contains microscopic imperfections that reduce thermal contact when combined with the high surface tension of water. EndoTherm™ breaks water hydrogen bonds and reduces surface tension to as low as 27 mN/m, compared to 71 mN/m in untreated water. This alters the way steam bubbles form at the nucleated boiling sites along the imperfections on the heating surfaces of fired boiler tubes.


EndoTherm is compatible with all types of metals used in heating systems, as well as with all corrosion inhibitors and glycols. EndoTherm comes in a ready-to-use solution with no additional equipment or maintenance required. EndoTherm is 100 percent organic and safe for sanitary sewers. The effectiveness of EndoTherm has been proven in extensive laboratory testing and in studies in thousands of systems and has won multiple building and eco-friendly awards.

Carbon Reduction

By significantly reducing the amount of energy consumed by hydronic heating systems, EndoTherm also provides a secondary benefit of reducing carbon emissions. To see the impact of EndoTherm on carbon emissions, read the case study below on Allegany College of Maryland and how it was able to cut its carbon output by 18.8%.

To learn more about EndoTherm™, watch the video.

Example of EndoTherm™ Energy Savings

Average Energy Bill:


EndoTherm Savings:


Typical ROI:

4 to 6 months

Typical Savings per Year:


Is EndoTherm™ right for your system?

Contact a Guardian water treatment specialist and request a free energy audit to find out if EndoTherm is right for your heating system.

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