The following is an excerpt from the Nov./Dec. edition of Water Canada‘s magazine.
“Rethinking pumps and pipes” – Hot ideas for moving warm water around the home, by Michael Anschel and Kerry Freek.
Even though hot water can be the first or second largest use of energy in many homes, not a lot of thought is given to moving it through buildings efficiently. Add domestic hot water use, filtration, and distribution networks, and the energy value of water becomes significantly larger than generally acknowledged. Think about turning on a shower. In many homes, it takes three or four minutes for hot water to reach the point of use. Meanwhile, a large volume of treated, potable water, pumped at a great cost through aging municipal distribution networks to residential taps is lost down the drain. When you turn up the thermostat, hot water flows through the entire radiator system, not just the rooms which need heat. From the simple to the extreme, here are a few possibilities for saving water and energy while maintaining a steady supply of hot water in a home.
Picking efficient water heaters and pumps: The first step in any home is to secure an efficient water heater. Generally speaking, there are four options: tank, tankless, combi, and hybrid. A tank heats water and stores it for when it’s needed. At its best, it is 54 per cent efficient. Tankless and combi units can reach 98 per cent efficiency and eliminate the risk of combustion gas spillage in the home. Combi units have the added benefit of replacing your boiler, making them attractive from a cost perspective. Hybrid tank heaters are marginally more efficient than tank heaters at more cost, headache, and negative side effects… Over the years, pump technology has become increasingly more efficient – today’s pumps use a fraction of the energy that older models do. A smart pump could make a significant difference, radically improving an old system… A smart pump can also learn patterns and makes predictions. For example, if you wake up and take a shower at 7 a.m., the pump will run the line at 6:55 a.m. and, by the time you get to the shower, hot water is ready and waiting. The same pumps can send heat to your bedroom, bathroom, and kitchen in the morning selectively, rather than to the entire home…Re-circulating systems can provide some of these same benefits. The pumps that control these systems can be operated by switch, motion detector, or remote control. Pushing a small button on the way to the bathroom in the morning, for instance, could trigger a small pump that silently runs the hot water line, returning the cooler water in the line back to the tank and drawing piping hot water up to the shower valve so that it’s hot when you get there…
An efficient system is half the battle: Switching from a tank to tankless system or replacing old model pumps with smart pumps may not make as much of an impact on energy bills if the delivery systems – that is, the pipes are inefficient. Switching an old 50 per cent efficient tank water heater to a high-efficiency tankless system will save energy, but in many cases even greater savings can be found by replacing or modifying inefficient delivery systems: the pipes. In many homes, the hot water heating station is a healthy distance from the point of use, such as a faucet. Residential systems may be better off with a new design approach – particularly in new construction. Here, the opportunity to completely rethink the layout of water pipes can yield the greatest amount of efficiency with the least amount of energy and resources…
Picking our battles: Understanding the value of a systems approach to hot water delivery and the opportunities that exist with high-efficiency smart pumps on our heating systems is an important first step. With minimal expense, we can easily modify existing systems and install new systems to be exponentially more efficient. We have an obligation to each other to make these changes a priority in our retrofit and new construction process.