ThermoDrain

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.

 

WHAT IS THE RESNET/ CRESNET HERS INDEX FOR HOMES?

Outside of a mortgage loan, the highest cost of homeownership is energy.
That’s why smart homebuyers ask for a home’s HERS Index Score to determine
its energy efficiency before buying. The HERS Index Score is like a MPG
(miles-per-gallon) sticker for homes. After all, it makes sense to know the
energy performance of a home before making the investment.

DRAIN WATER HEAT RECOVERY AND ITS IMPACT ON THE RESNET HERS INDEX 

Drain water heat recovery will increase energy savings, improve home comfort and reduce carbon foot print. It is considered one of the most cost effective ways of reducing the cost of heating water, the second largest energy consumption in a home.  

Home Energy Rating System (HERS)

Potential credits:              up to 2.1              (70 index home)

 

http://www.resnet.us/standards/RESNET_DWHR_Tool_(rev01).xlsx  

http://www.resnet.us/standards/ANSI_RESNET_301-2014_Addendum_A-2015.pdf

 

DRAIN WATER HEAT RECOVERY SYSTEMS HERS INDEX POINTS RESNET DETAILS
USE THE CALCULATOR TO DETERMINE POINTS OR LATEST HERS SOFTWARE (POST 2016)

extracted from http://www.resnet.us/standards/ANSI_RESNET_301-2014_Addendum_A-2015.pdf

Drain Water Heat Recovery (DWHR) – A heat exchanger unit that uses outgoing warm drain water to pre-heat incoming cold freshwater, is rated for efficiency and pressure loss according to CSA B55.1, and complies with CSA B55.2.
Tmains – The temperature of the potable water supply entering the residence.
Add new Normative References to Section 6
CSA B55.1-12, (2012). “Test method for measuring efficiency and pressure loss of drain water heat recovery units.” CSA Group, Mississauga, Ontario, Canada L4W 5N6.
CSA B55.2-12, (2012). “Drain water heat recovery units.” CSA Group, Mississauga, Ontario, Canada L4W 5N6.

NOTE: THERMODRAIN IS CSA 55.1 and CSA 55.2 certified

Table 4.2.2.5.2.11(1) Hot water fixture effectiveness

Plumbing Fixture Description

Standard-flow: showers ≤2.5 gpm and faucets ≤2.2 gpm Feff = 1.00

Low-flow: all showers and faucets ≤2.0 gpm  Feff = 0.95

adjFmix = 1 – ((Tset – Tuse)/ (Tset – WHinT))

where

Tset = 125 oF = water heater set point temperature

Tuse = 105 oF = temperature of mixed water at fixtures

WHinT = water heater inlet temperature

where

WHinT = Tmains + WHinTadj for DWHR systems and where WHinTadj is calculated in accordance with equation 4.2-14

WHinT = Tmains for all other hot water systems

Tmains = temperature of potable water supply entering the residence calculated in accordance with Section 4.2.2.5.1.4

refFgpd = reference climate-normalized daily fixture water use calculated in accordance with Section 4.2.2.5.1.4

 

4.2.2.5.2.11.1 Drain Water Heat Recovery (DWHR) Units

If DWHR unit(s) is (are) installed in the Rated Home, the water heater potable water supply temperature adjustment (WHinTadj) shall be calculated in accordance with Equation 4.2-14.

WHinTadj =Ifrac*(DWHRinT-Tmains)*DWHReff*PLC*LocF*FixF Eq. 4.2-14

where

WHinTadj = adjustment to water heater potable supply inlet temperature (oF)

Ifrac = 0.56 + 0.015*Nbr – 0.0004*Nbr2 = fraction of hot water use impacted by DWHR

DWHRinT = 97 oF

Tmains = calculated in accordance with Section 4.2.2.5.1.4

DWHReff = Drain Water Heat Recovery Unit efficiency as rated and labeled in accordance with CSA 55.1

where

DWHReff = DWHReff *1.082 if low-flow fixtures are installed in accordance with Table 4.2.2.5.2.11(1)

PLC = 1 - 0.0002*pLength = piping loss coefficient

where

for standard systems: pLength = pipeL as measured accordance with Section 4.1.1.5.2.11

for recirculation systems: pLength = branchL as measured in accordance with Section 4.2.2.5.2.11

LocF = a performance factor based on the installation location of the DWHR determined from Table 4.2.2.5.2.11(4)

 

Table 4.2.2.5.2.11(4) Location factors for DWHR placement

DRHR Placement

LocF

Supplies pre-heated water to both the fixture cold water piping and the hot water heater potable supply pipingLocF = 1.000

Supplies pre-heated water to only the hot water heater potable supply piping  0.777

Supplies pre-heated water to only the fixture cold water piping 0.777

 

FixF = Fixture Factor

where

FixF = 1.0 if all of the showers in the home are connected to DWHR units

FixF = 0.5 if there are 2 or more showers in the home and only 1 shower is connected to a DWHR unit.