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A “Better Idea” Real World Example

November 18, 2020

Long ago, Lochinvar developed a solution to heating domestic hot water called “The Better Idea”. The simple concept is to separate the storage of hot water from the gas-fired production of hot water. The high temperatures experienced near the combustion chamber can cause minerals to come out of solution at this critical location and degrade performance. Lochinvar specifies pump conditions to maintain enough velocity in the heat exchanger to keep it clean and at top efficiency. Recommended pump flow rates for the same firing rate change for harder water applications, is one example.

An inherent advantage of this solution is that storage volume and input firing rate can be better selected to match the building loads and any space limitations. For example, its easier to move two smaller tanks than a single big one.   

It also allows for the stored water to be supplied heat from multiple sources, in order to increase a system’s redundancy. This design flexibility appealed to a local high school that was going through a renovation. The school was expanding and looking to replace some of their aging equipment as the original tank water heaters were approaching the end of their useful life. Replacing the entire domestic hot water system allowed them to tap into the central hot water system as the primary source of heat. There were times however where the central plant would not be operating so a second source of heat would be needed.   

The design quickly came together using Lochinvar’s comprehensive product offering. A custom Lochinvar glass-lined tank was selected and fitted with a u-tube heat exchanger. A horizontal tank was selected due to ceiling height restrictions. A pump circulates between the tank and the Lochinvar ARMOR 1,250,000 Btu/hr. The ARMOR fully modulating firing control efficiently keeps the tank up to temperature when the central boiler plant is not available. The single source nature of the design ensures that all the pieces will work together.

This is just another example of how the decades old “Better Approach” can be used to produce an efficient and reliable potable hot water heating system.


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