By Bob Silva
Heating and delivering water throughout buildings is a challenge that all architects and engineers must confront.
Now, electric heat-traced single-direction hot water delivery systems can drive efficiency, safety, and water savings. These systems are deployed in multifamily, condominium, and residential housing, as well as in hotels, offices, hospitals, schools, and other commercial and institutional buildings.
Traditional hot-water systems recirculate water throughout buildings via a circulation loop. Unused water is returned to the water heater and reheated to keep it hot enough to meet the needs of building occupants. Especially in the case of tall buildings like offices, residential buildings, and hotels, recirculation systems require that water-heater temperatures are at least five degrees above the desired temperature coming out of the faucet since water loses heat as it is circulated through pipes. This pumping and overheating process wastes energy and building recirculation loops add unneeded material and labor costs to construction projects.
Electric heat-traced single-pipe systems consist of sensors near the hot water heater, an electronic controller to control water temperature, and insulation and self-regulating heating cables on the hot water pipes to maintain hot water temperature to points of use. These systems can deliver virtually instant hot water as soon as building occupants turn on the tap, all but eliminating wasted water used while people wait for hot water to heat up. Reducing the amount of water going down the drain while waiting for hot water to arrive also reduces expensive sewer-discharge fees.
Electric heat-traced water-heating systems can drive sustainability through a combination of efficient heating and smart controllers. In addition to reducing wasted water, they provide flexible temperature control with controllers that deliver energy savings by intelligently using only the power that is necessary to maintain targeted temperatures. These systems can also be programmed off during known days or periods of non-use to further minimize energy consumption. Furthermore, they are eligible for LEED points for Innovation in Design and energy conservation, which validates their potential to save energy.
In addition to energy savings, electric heat-trace systems make submetering simpler and less expensive to implement since the system is one-way. Submetering also makes it easier for occupants to track and address their individual water consumption as well as for building owners to monitor the water use of individual tenants. Additionally, electric temperature control systems can effectively maintain the temperatures required for building services’ Legionella risk-management programs. For additional information for the proper design, installation, operation, maintenance, and management of your building water systems to minimize the risk of Legionella Disease, see ASHRAE 188-2018 and CIBSE TM13: 2013.
Creating A Resilient System
Ensuring systems are built to last is also a critical piece of sustainability in commercial construction. Using materials and systems that will not need to be replaced and thrown away is an important consideration. While controllers in electric heat-trace systems may require maintenance and updates as new technology emerges, the lifespan of quality heat-trace cables can easily exceed the expected life of commercial piping of 20-25 years. With the heating system lasting as long as the pipes it supports, architects and engineers can be confident in the long-term viability of these systems.
Electric heat-trace hot-water delivery systems are also flexible and save valuable space. The space requirement for pipes is reduced, because no return pipe is present. Risers, shafts, and openings can also be minimized, freeing space for other services.
Buildings often evolve and change over time. For example, an existing building may have extra stories or an extension added, or a floor reconfigured. Different floor plans within a building are also not a problem because the heating cable simply attaches to the hot water piping regardless of the unit’s configuration. New parts of the building can be connected to existing hot-water delivery systems easily, rapidly, and economically with single pipe heat-traced hot-water lines since they do not require any hydraulic compensation. There are no additional pumps, control valves, or double water meters needed, and the time-consuming and expensive installations of return pipes is unnecessary.
Even with new construction combining recirculated hot water mains and single heat-traced pipe systems for the horizontal piping, it is often the best of both worlds. The engineer can simply heat-trace the horizontal hot-water lines within each floor or unit to provide instant hot water and meet energy and water usage codes.
An Enhanced Experience For Occupants
Alongside the sustainability, efficiency, flexibility, and safety reasons to implement electric heat-traced hot-water delivery systems, these systems are also simply very convenient and add an ease of use and enjoyment factor for occupants. Who wouldn’t want instant hot water? Not having to wait for hot water to arrive at your sink or shower not only saves water but also creates a more positive day-to-day experience for building occupants.
Efficiently delivering hot water has become a crucial aspect of conserving resources and reducing costs. Specifying the use of heat-traced single pipe solutions provides an innovative approach to hot water temperature maintenance that can help achieve goals such as decarbonization, submetering, sustainability, and energy/water savings. These solutions are a reliable, long-lasting, and cost-effective option for a wide range of applications such as multi-unit residential buildings, schools, offices, and more.
Silva is an expert in electric heat tracing and thermal management at nVent. Silva has more than 20 years of experience in operations, sales, product management and marketing for electric heat trace products.