Legionnaires’ disease Prevention

Installing a master mixing valve on a domestic hot water system adds an extra layer of safety.

By Rick Cota and Eric Costa

 

Leonard Valve's Nucleus digital mixing valve provides complete system monitoring with outlet temperature control within +/- 2° F from setpoint, regardless of demand. 

 

Hot water has been around since man first harnessed the power of fire, but when at elevated temperatures, it is dangerous and even deadly. Today’s hot water heaters offer a diverse range of technologies that perform leaps and bounds ahead of their predecessors, but what temperature should they deliver? Some facilities may simply set the heater to a usable temperature, but while this may seem like an acceptable practice, there is an issue that needs to be addressed: Legionella. 

One of the biggest concerns for hot water systems in commercial buildings is Legionella bacteria. Legionella is a bacterium that enters the human body by inhalation and aspiration of water droplets, and is responsible for Legionnaires’ disease, a bacterial infection of the lower respiratory system that often gets misdiagnosed as pneumonia; one in 10 people who contract Legionnaires’ disease will not survive. Below is a Legionella Growth Chart, which shows the bacteria growth behavior. These organisms live and multiply in water between 68° F and 122° F and thrive in water 95° to 115°. At 121°, Legionella bacterium stops multiplying but is still present in water.  

 

There are many ways to combat Legionella in a domestic hot water system. UV light treatment is a method used to treat bacterial removal; however, additional heat is the most common method. Since the first clinical study was done in 1977 by the Allegheny County Health Department, more and more commercial water heater systems are heating to temperatures above 140° to kill the bacteria. Since then, the plumbing design industry generally follows the ASHRAE 2000-12 guideline, which suggests thermal disinfection by sending hot water 165° to 175° through the domestic hot water system. 

These higher temperatures, while necessary, pose a scald danger for end users. This is where a master mixing valve becomes extremely valuable. A master mixer is regularly used to reduce the temperature down to a more usable area (between 124° to 130°), and then circulated throughout the building. A portion of the return water from the domestic hot water line is sent back to the hot water source to be reheated, which helps keep Legionella growth in check. 

Master mixing valves provide a buffer between the high-temperature heat source and endpoint fixtures. Hand washing faucets in public restrooms will typically have hot water supplied from a small point-of-use mixing valve. The presence of these valves will tempt designers and contractors to skip the installation of a master mixing valve. While this does work initially, the building is at a higher risk of scalding end users since these small valves are often forgotten and not well maintained. Over time, these valves will fail and potentially allow “full hot” through them. If “full hot” is 140° or above, the risk of scald is significant. By installing a master mixing valve, “full hot” is tempered down to the fixtures keeping a set temperature safe for end users. For reference, below is a water burn chart so that the danger can be fully appreciated.

 

Master mixing valves also keep domestic hot water temperatures consistent, even with large inlet temperature changes. As part of the ASSE 1017 certification, all master mixers must control the outlet temperature within a specified range from the initial set point when there is a 25° increase to the hot water inlet temperature. The allowable variance can range from ±3° to ±7°, depending on the size and flow rate. Most thermostatic master mixers hold to within ±3°, and digital master mixing valves are known to hold within ±2°. Without a master mixing valve, a large increase in hot water temperature can be a dangerous situation. 

Pressure-balanced shower valves are of particular concern since they do not offer thermal protection; large increases to the domestic hot water temperature will be directly felt by the end user. If a master mixing valve is installed, the large increase in hot water temperature from the heat source is tempered down and end users are better protected.   

 

Energy and cost savings are other benefits of installing a master mixing valve. Instead of having to heat 100% of the hot water needed for the building, the heater is only needed for a fraction of that when a master mixer is present in the system. Consider a system that requires a domestic hot water temperature of 125°. If the hot water supply is set to 140° with a mixing valve installed downstream, 83% of the volume needs to be heated, assuming the cold-water temperature is 50°. At 160°, only 68% of the domestic hot water needs to be heated. This reduction will save the facility energy and the system becomes environmentally friendly. In addition, since the heaters are heating a lower volume of water, a smaller unit may be sufficient and wear and tear to the heater and related equipment is reduced.

Installing a master mixing valve on a domestic hot water system is simply good practice. They add an extra layer of safety to any system. Having a master mixer allows facilities to heat and store water at elevated temperatures, which kills Legionella bacteria while delivering safe hot water temperatures for multiple applications. If a heating system malfunctions and a large increase in the hot water temperature is seen, a master mixing valve will flatten the spike to the domestic hot water system. The inclusion of a mixing valve will also save energy and lengthen heater equipment service life.

 

How are Merges & Acquisitions Revolutionizing the Market for Tankless Water Heaters?

Tankless water heater manufacturer are focusing on expanding their technological and manufacturing capabilities through strategic mergers and acquisitions across value chains. Especially, North Americas and Asia Pacific giants are focusing more on strategically acquiring small and medium manufacturers to expand their product lines and complement their manufacturing capabilities.

 

• Rinnai America Corporation, one of the prominent manufacturers of tankless water heaters, offers Amazon's integration with Alexa and its products, allowing users to ask Alexa to start circulating water. In addition, the company’s products are incorporated with Google Home, allowing users to monitor their tankless system’s recirculation and temperature.

 

• In December 2020, Bradford White Corporation, entered into a strategic partnership with Bradley Corporation for the acquisition of Keltech Inc., which would help the company enlarge its commercial electric products portfolio and prepare for further adoption of electrification initiatives by communities throughout North America.

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Will Growth in Construction and Manufacturing Activities Continue Driving Sales of Tankless Water Heaters?

Middle-income economies with a high population base in developing countries such as China, India, and South Africa are observing robust growth in recreational and construction activities. Long-term structure planning of governments and initiatives taken by them, coupled with positive industrial outlook of various business sectors, are projected to be the prime reason driving the growth of manufacturing and construction activities in developing economies.

Steady raw material prices, increased spending power, and steady interest rates as home loans are promoting home owners to invest in purchasing new homes, are estimated to drive tankless water heater demand.

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Will Replacement of Existing Water Heaters With High-energy Heaters Shape Market Growth?

Utilizing and optimizing available energy resources efficiently is considered to be one of the top priorities of governments all over the world. These sustainability goals of governments are estimated to create rapid replacement of high-energy consuming heaters to low-energy water heaters.

Government rebates and subsidies as well as changing perception of consumers toward water heaters with high energy factors are promoting the rate of replacement of water heaters with tankless water heaters.

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How Has COVID-19 Affected the Market? 

The ongoing COVID-19 pandemic has affected the global economy in various ways. It has led serious implications for most manufacturers of tankless water heater products in the form of supple chain disruptions. The crisis has decreased the purchasing capacity of consumers. Also, limited availability of raw materials, shortage of labor supply, and limited availability of components have drastically impacted market growth.

Besides this, the outbreak of COVID-19 further resulted a drastic change in consumer buying behavior. Shift in consumer spending from non-essential to essential products further impacted sales in the initial period of the outbreak, as such, posing numerous challenges on the sales front.

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Category-Wise Insights

Why Does the Residential Segment Dominate Demand for Tankless Water Heaters?

The residential application segment accounted for a significant share of 1/4 in 2019. Increasing acceptance of eco-friendly and energy efficient products, including tankless water heaters, is a major factor driving demand in the residential sector. Further, mounting number of residential units and construction projects due to the rising number of the middle-class people, especially in developing countries such as India, China, and others, is expected to encourage the adoption of these solutions over the coming years.

In addition, improving quality and standard of living, coupled with changes in consumer preferences toward energy-efficient products, including tankless water heaters, is expected to remain a positive factor for the growth of the industry. Moreover, introduction of new products with innovative and advanced features is expected to open up new avenues. For instance, Rheem's Prestige models with EcoNet Smart Technology offers Wi-Fi connectivity and additional features, providing system protection, control, and cost savings.

 

Is Condensing Technology Gaining More Popularity?

The condensing segment accounted for around 3/4 market value share in 2020, and is expected to exhibit fastest growth registering a CAGR of more than 8% over the forecast period. Condensing tankless water heaters are more energy efficient when compared to non-condensing tankless water heaters, and are gaining significant penetration in emerging economies. This segment is expected to be the most attractive segment, due to greater emphasis of various governments and private bodies on setting up power plants to harness renewable energy sources such as solar and wind, which is creating significant market opportunities for key players across the globe.

 

Electric or Gas - Which Energy Source is Better?

Electric tankless water heaters are estimated to account for around 80% market share by the end of 2031. Global sales revenue of electric tankless water heaters is expected to increase at a CAGR of more than 5% over the next ten years. Easily available electrical energy sources and factors such as lack of availability of fuel such as natural gas or propane, as well as poor gas supply infrastructure, especially in developing economies, are considered to be the major factors driving demand for electric tankless water heaters.

 

Which Energy Factor Is More Efficient?

Energy factor – 0.80 to 0.89 EF is estimated to account for around 1/3 in terms of value share by end of 2021, and is expected to register a CAGR of over 6% throughout the forecast period. Rising demand due to availability of a wide variety of products as well as price being an essential factor are making middle-class consumers prefer 0.80 to 0.79 EF, keeping in mind better energy efficiency at a reasonable cost.

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