Drain water heat recovery - Récupérateur de la chaleur des eaux de drainage

Drain water heat recovery (DWHR). ThermoDrain is a drain water heat recovery unit that recovers energy from waste water and transfers this energy to potable water before entering a water heater. It is different from other heat exchangers in that it has dual walls vented to the atmosphere so that cross contamination between wastewater and potable water is not possible. The heat transfer occurs only when wastewater is flowing down the drain while there is a demand on the hot water heater. This technology can save the homeowner up to 40% on their water heating bills. It can also triple the capacity of a hot water tank for showering. It is considered a comfortable green technology designed for shower lovers who also want to save energy. ThermoDrain is a superior drain water heat recovery technology that is manufactured in North America and comes with an industry leading 10 year warranty.



NOTE: Drain water heat recovery is mandatory when you are building to the Ontario building code prescriptive path. Always verify applicability of the code with your building inspector or your energy efficiency advisor.



(1) Except as provided in Sentence (2), a drain water heat recovery unit shall be installed in each dwelling unit to receive drain water from all showers or from at least two showers where there are two or more showers in the dwelling unit. (See Appendix A below.)

(2) Sentence (1) does not to apply to dwelling units in which:
(a) there are no showers; or
(b) there are no storeys or crawl spaces beneath any of the showers in the dwelling unit.

(3) Drain water heat recovery units shall conform to CSA B55.2, “Drain Water Heat Recovery Units”.

(4) The minimum efficiency of a drain water heat recovery unit shall be determined in conformance with CSA B55.1, “Test Method for Measuring Efficiency and Pressure Loss of Drain Water Heat Recovery Units”.

(5) The efficiency of a drain water heat recovery unit, when tested in accordance with Sentence (4), shall be not less than 42%.

(6) A drain water heat recovery unit shall be installed
(a) in an upright position that does not diverge more than 5 degrees from the vertical,
(b) in a position such that the cold water inlet connection is at the bottom of the unit,
(c) downstream of a water softener where a water softener is installed, and
(d) in a conditioned space or on the warm side of the dewpoint of the wall assembly.


Appendix A

A- Shower Drainage Installation.
The term “all showers” includes the case where there is only one shower in a dwelling unit. If there is only one shower, that shower is required to be connected to a drain water heat recovery unit. Where there are two or more showers, drain water from at least two showers are required to be connected to a single drain water heat recovery unit or to two individual drain water heat recovery units.




1) "DWELLING UNIT" means one or more rooms located within a building and used or intended to be used for human habitation by one or more persons with cooking, eating, living and sleeping facilities and with separate sanitary facilities.

2) "STOREY" means that portion of a building which is situated between the top of any floor and the top of the next floor above it, and if there is no floor above it, that portion between the top of such floor and the ceiling above it.


ThermoDrain & The Ontario Code

  1. A ThermoDrain drain water heat recovery device must be installed on a shower in a residential dwelling such as a home, condominium or apartment.
  2. If more than one shower is in the home, at least two showers must be hooked to the ThermoDrain.
  3. The ThermoDrain must be at least 42% efficient. The efficiency must be CSA B55.1 certified and the unit must be safety certified to CSA B55.2. ThermoDrain has both these certifications. The model used to meet the code requirement is the TD342B.
  4. The ThermoDrain must have the cold water hooked to the bottom of the unit.
  5. Preheated water from the ThermoDrain can be installed in 3 different ways.
    a) Preheated water is sent to the inlet of the hot water tank,
    b) Preheated water is sent to the cold outlet of the shower
    or c) Both a) and b)
  6. Drain water heat recovery is not required where there is no stories beneath the shower in the home.
  7. For complex installations such as condos, apartments where a drain stack is shared with several dwellings, the MURBS guide will help determine how to install this technology and meet the code requirements.

    A guide will be available soon or you can contact us for immediate assistance.