All ecodrain products are designed to efficiently recover heat from drain water. Which model is best for a given application depends on where the unit will be installed.

Vertical drain water heat recovery systems are the most common. They are for vertical drain stacks only. They are recognized by energy codes in several places and some utlities provide incentives for their installation. In general, if there is a vertical drain stack below the shower for which the unit is to be installed, then vertical is the preferred option. Please check our V1000 product page for more information about our vertical drain water heat recovery systems.

An exception to this is homes with multiple showers and multiple vertical drain stacks. In these applications, a single horizontal main drain line unit simplifies the installation and may offer the best payback. Please see our B1000 product page for more information about this application.

In many applications, horizontal drain water heat recovery is the only practical option. It may be possible to pump drain water into a vertical heat exchanger but this is not a cost effective solution. In horizontal applications, such as single story homes, homes built on crawl space, home with partial basements etc, horizontal drain water heat recovery is the preferred option. We have developed two solutions for these applications:

B1000 for main drain line applications. This is a heat exchanger on the outside of a regular copper drain line.

A1000 for grey water only applications (waste water excluding toilet water). The A1000 is much shorter for the same level of performance, but is not recommended for installation on mixed water drain lines.

The two main options for a multi-family are horizontal main drain line heat exchanger on the final drain, and vertical heat exchangers on the vertical drain stack.

A main drain line heat exchanger, combined with a heat pump, can provide the greatest possible savings while also simplifying installation. Since the main horizontal drain line collects the water from multiple vertical drain stacks, installing a series of heat exchangers on a the horizontal drain line is most likely easier than installing a vertical heat exchanger on each drain stack. If the building has central heating and cooling, the cold side loop of the drain water heat exchanger can be connected on a closed loop to a heat pump to provide space heat as well as hot water.

Connecting to the heat pump provides the potential for greater savings because useful energy can be recovered from hot and cold water. When using a heat pump, the inlet to the cold water side can be set at a lower temperature, for example 4C, even if the unheated water in the area is typically warmer in the range of 7C-20C. By recovering energy from both the hot and cold water, when possible, this set up will recover significantly more energy than any other option.

The second option is to install vertical drain water heat recovery systems on the vertical drain stacks in order to preheat water into each unit of that level which shares the drain stack. If each apartment has its own water heater, the preheated outlet can be connected to the inlet of each water heater. If the building has a central water heater, then the preheated outlet of the heat exchanger can be connected to the cold side of the shower mixing valve in each apartment.

CSA B55 is a standard for drain water heat recovery systems. There are two parts to CSA B55; CSA B55.1 and CSA B55.2.

CSA B55.1 is a standard for performance testing of heat exchangers in a lab setting. It sets the conditions under which heat exchangers must be tested in terms of temperatures and flow rates of the cold and warm water. It was developed as a method to standardize and compare test results for different models and sizes of heat exchangers, ensuring that they are all tested under the same conditions and that the tests are condutcted independently.

CSA B55.2 is a product standard. It was developed in order to ensure that drain water heat recovery systems are safe to use in homes and buildings. It specifies the materials that are allowed to be used, and how they are allowed to be joined together, and the conditions under which they must be tested for safety.

Effectiveness is a measure of the performance of a heat exchanger. It is measured as the ratio of the temperature gained in the preheated water versus the total potential gain.

Calculation: (temp of preheated outlet – temp of cold water) / (temp of drain water entering heat exchanger – temp of cold water)

The effectiveness of a heat exchanger depends on its type, size, and the conditions under which it is tested. Please refer to the product pages for information about their effectiveness.

The most basic equation governing the heat required to change the temperature of water is:

Q = m Cp dT , where

Q = heat transferred per second in kilowatts (kW)

m = mass flow rate of water (kilograms / second)

Cp = heat capacity of water (kJ / kg K), a constant for a given material. The number of kilojoules of energy required to heat one kilogram of water by one degree Kelvin.

dT = delta T = change in temperature of water being preheated

In the case of a bath, hot water fills the bath and only later drains after it has cooled. When the bath is draining, there is not necessarily any fresh water on its way to the water heater to be preheated.  For these reasons, installing for a bath-only application is not ideal for this technology.

For residential dishwashers and laundry, the same constraint applies in that water is filled into the machine at first, and then drained several minutes later. 

In the case of commercial dishwashers, which are used for multiple cycles at a time, a lot of energy can be recovered. In fact, ecodrain was tested successfully for commercial dishwashers by the food service technology center. The test report is available here. 

All scenarios will provide very high savings compared to not installing a heat exchanger so if you have decided to install the heat exchanger, you can look forward to savings. 

In some scenarios, such as if the water heater is very far from the shower, it is more practical to install the heat exchanger such that water to the cold side of a shower fixture is preheated.

In other scenarios, such as when an exposed pipe is located near the water heater, it might be more convenient to install the heat exchanger to preheat water to the water heater. 

On a purely theoretical level, and when installation permits it, the greatest potential savings will come from preheating water to both the water heater and the cold side of the shower valve. The reason is that the flow of cold water through the heat exchanger increases. For reasons beyond the scope of this explanation, as the flow rate increases, the rise in temperature decreases, but the impact of the temperature decrease is less than the impact of the flow increase. Another way to think about it is that with a higher cold water flow rate, the heat exchanger works harder, and produces more energy. 

To understand why, consider the equation from the previous question:

Q = m Cp dT

In order for Q to go up, either m or Cp or dT must increase. Since Cp is a constant, we focus on m and dT. m and dT are inversely proportional, which means that as the flow rate (m) increases, the temperature rise (dT) decreases.  As the flow rate increases, the temperature decreases but not as much as the flow rate has increased, resulting in an increased energy transfer. 

No.  Ecodrain allows heat to be transferred from hot drain water to cold fresh water, while keeping them safely separated by a double wall.

In one application, ecodrain can be used to preheat water to the cold side of a shower valve. As the cold water temperature increases, the output temperature of the shower will increase unless an adjustment is made to reduce the flow of hot water and increase the flow of cold water. A thermostatic valve is designed to automatically maintain a constant output temperature despite variations in incoming water temperature. It does this by restricting the flow of hot water and increasing the flow of cold water as the cold water temperature rises. 

No. Horiozntal drain lines are always sloped in order to allow for liquids to evacuate the building.