HOW DOES DRAIN WATER HEAT RECOVERY WORK?

A simple, comfortable and maintenance free passive water heater booster that uses waste heat energy to preheat incoming cold water. 

IS DRAIN WATER HEAT RECOVERY WORTH THE INVESTMENT ?

Drain water heat recovery recovers heat from water that would otherwise be lost down the drain. It works best with simultaneous flows like showers, where there is a demand for hot water at the same time as hot water is going down the drain. The recovered heat can be used to preheat cold water going to the hot water tank or for other purposes permitted by codes and regulations.

A ThermoDrain 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. ThermoDrain systems provide greater potential for energy savings as the number of simultaneous flows increases.

 

Water heating accounts for 20 – 40% of the total energy consumption in a typical home, DWHR units can reduce hot water requirements for showering by 40 to 60%.

DRAIN WATER HEAT RECOVERY BENEFITS

Manitoba Hydro Estimates that you will save over 25% on the cost of heating water with drain water heat recovery.

Hydro Quebec estimates that you will save between 20% and 40% on the cost of heating water with drain water heat recovery.

Enbridge Gas estimates that you will save 30% on the cost of heating water with drain water heat recovery

Other Benefits

  • Energy savings
    A typical drain water heat recovery system can reduce your water heater’s energy consumption by up to 25%. Less energy consumption means lower energy bills for you.
  • Extend the life of your water heater
    Since the cold water entering your water heater is pre-heated by the drain water heat recovery system, the water heater does not have to work as hard to heat the water so your water heater may last longer.
  • Flexibility
    A drain water heat recovery system is compatible with any type of water heating system and as technology changes over time, your drain water heat recovery will reduce the energy consumption of any future water heating system you choose for your home.
  • Simplicity and reliability
    A drain water heat recovery system is made of copper, has no moving parts, and requires no regular maintenance. The system has a product life of well over 30 years. Once it is installed, you can simply forget about it and enjoy the reduced energy consumption and utility bill savings it provides.
  • More hot water
    Overall flow rates on tankless will increase and you will experience 3x more hot water for showering with a tank heater.

Five year limited warranty

Manufactured to the strictest of code requirements to surpass reliability and safety standards.

COMPARING TWO DIFFERENT LENGTH DRAIN WATER HEAT RECOVERY UNITS

Scenario 1 (33.5″ long drain water heat recovery unit)

  • TDH3335B 42.1% efficient (1.26% efficiency per inch) – Highest efficiency per inch and the lowest embodied carbon on the market for DHWR.
  • Drain water temperature 100°F
  • Cold water temperature 50°F
  • DELTA T = 50°F
  • Temperature increase = 50°F x 42.1% = 21°F
  • 50°F cold + 21°F ThermoDrain increase = 71.0°F ThermoDrain supplied preheated water at the same flow rate as the configuration you have sent the preheated water in. (Example: Connected in equal flow will give you 9.5 to 7.6 Lpm of increased temperature flow rate)

Scenario 2 (62″ long drain water heat recovery unit)

  • TDH3620B 57.2% efficient
  • Drain water temperature 100°F
  • Cold water temperature 50°F
  • DELTA T = 50°F
  • Temperature increase = 50°F x 57.2% = 28.6°F
  • 50°F cold + 28.6°F ThermoDrain increase = 78.6°F ThermoDrain supplied preheated water2

THERMODRAIN IS EASY TO INSTALL WITH
PRE-INSTALLED PEX or EXPANSION PEX FITTINGS

The ThermoDrain, drain water heat recovery installation is EASY. There is no soldering required with the optional patent pending crimp style PEX fitting feature.  The ThermoDrain is installed vertically on the main drain stack in order to capture most of the hot waste water used. The preheated potable water from the ThermoDrain may be fed in a variety of configurations to either or both the water heater and cold side of the plumbing fixtures using hot water. No maintenance is required, it has a very low pressure drop and has been designed with outstanding efficiency. The ThermoDrain is easy to install and takes no more than 45 minutes with some plumbing experience.

Simple Installation Options Model Selection

WHAT MODEL DRAIN WATER HEAT RECOVERY UNIT SHOULD I USE?

Where drain water heat recovery is code required, the code usually states are minimum requirement of 42% efficiency. This number must be verified by a third party to the CSA B55.1 standard. If you are not required by code to use drain water heat recovery and wish to install and do not know where to begin, look at the cost versus efficiency in percent. Each dollar invested in drain water heat recovery is buying you a point in efficiency. By using this graph, you can determine the efficiency versus length and cost out what unit suits your needs. In the case where you are building to a NETZERO or PASSIVEHOUSE standard, you will want the longest unit possible because the cost of the energy recovered using this technology beats out cost per energy recovered. 

Your selection should take into account the available length of the 3” drain pipe where the unit will be installed as well as the efficiency you wish to obtain. The models proposed are all suited for residential installation and should be located on the vertical drain stack that services at least one shower and most of the appliances using hot water.

Visit our ThermoDrain, rain water heat recovery model selection guide or view our installation guide for residential applications.