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https://www.energy.gov/energysaver/drain-water-heat-recovery https://www.energy.gov/energysaver/drain-water-heat-recovery > Drain-water heat recovery technolog

by shagie 3y ago

https://www.energy.gov/energysaver/drain-water-heat-recovery https://www.energy.gov/energysaver/drain-water-heat-recovery > Drain-water heat recovery technology works well with all types of water heaters, especially with demand and solar water heaters. Drain-water heat exchangers can recover heat from the hot water used in showers, bathtubs, sinks, dishwashers, and clothes washers. They generally have the ability to store recovered heat for later use. You'll need a unit with storage capacity for use with a dishwasher or clothes washer. Without storage capacity, you'll only have useful energy during the simultaneous flow of cold water and heated drain water, like showering. > ... > Purchase prices for drain-water heat recovery systems range from $300 to $500. You'll need a qualified plumbing and heating contractor to install the system. Installation will usually be less expensive in new home construction. Paybacks range from 2.5 to 7 years, depending on how often the system is used, and the temperature of the incoming water, which is dependent on ground temperatures.

zbrozek 3y ago
How do you actually implement this? Waste pipes are huge compared to supply pipes, and rarely take even remotely similar paths. In my home, which I'm repairing right now, I have one water heater but three different waste egresses from the house.
- shagie 3y ago
  https://www.kitchenandbathclassics.com/eco-friendly/advanced-plumbing/drain-water-recovery/ https://www.kitchenandbathclassics.com/eco-friendly/advanced... > A DWHR unit consists of copper pipe tightly wound around a vertical section of copper drainpipe. As water flows down the drainpipe, it clings to the inside surface of the drainpipe. The heat from the drain water is transferred through the copper drainpipe to fresh cold water flowing in the outer copper coil. > The warmed water is then sent either to the hot water tank or other permitted end-use. In either case, the amount of energy needed to provide hot water is reduced. DWHR systems provide greater potential for energy savings as the number of simultaneous flows increases. The Home Depot version: https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Water-Heat-Recovery-Unit-R3-48/203456041 https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Wa... You wouldn't necessarily need this on every waste water egress. In my house, I've got one shower egress route that it would make sense on. The kitchen (I don't have a dish washer) doesn't run hot water for long enough for it to be reasonable - nor the 2nd floor bathroom with just a toilet and sink. (edit) There are spots where (in my house for example), this could be more useful. For example, that 2nd floor bathroom I've looked at a tankless water heater for the sink (so that I don't have to pull hot water from far away and then could simplify to only need to run cold water). Capturing the hot water there and returning the heat there there may make some sense... though for just a sink that would be a long ROI time.

by shagie 3y ago

zbrozek 3y ago

How do you actually implement this? Waste pipes are huge compared to supply pipes, and rarely take even remotely similar paths. In my home, which I'm repairing right now, I have one water heater but three different waste egresses from the house.

shagie 3y ago
https://www.kitchenandbathclassics.com/eco-friendly/advanced-plumbing/drain-water-recovery/ https://www.kitchenandbathclassics.com/eco-friendly/advanced... > A DWHR unit consists of copper pipe tightly wound around a vertical section of copper drainpipe. As water flows down the drainpipe, it clings to the inside surface of the drainpipe. The heat from the drain water is transferred through the copper drainpipe to fresh cold water flowing in the outer copper coil. > The warmed water is then sent either to the hot water tank or other permitted end-use. In either case, the amount of energy needed to provide hot water is reduced. DWHR systems provide greater potential for energy savings as the number of simultaneous flows increases. The Home Depot version: https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Water-Heat-Recovery-Unit-R3-48/203456041 https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Wa... You wouldn't necessarily need this on every waste water egress. In my house, I've got one shower egress route that it would make sense on. The kitchen (I don't have a dish washer) doesn't run hot water for long enough for it to be reasonable - nor the 2nd floor bathroom with just a toilet and sink. (edit) There are spots where (in my house for example), this could be more useful. For example, that 2nd floor bathroom I've looked at a tankless water heater for the sink (so that I don't have to pull hot water from far away and then could simplify to only need to run cold water). Capturing the hot water there and returning the heat there there may make some sense... though for just a sink that would be a long ROI time.