Hot water recirculation

Assumptions: 

Assuming that an average household consists of 3 persons in average water waste a year is estimated to be 16.425 liters equals 66 bathtubs and 37 hours waiting a year 

  1. Number of times a person is waiting a day for water to get hot at a faucet is estimated to be 5 https://energysavingtrust.org.uk/sites/default/files/reports/AtHomewithWater(7).pdf  
  2. Number of liters wasted each time at a faucet is estimated to be 2 liters, with a faucet having a flow of 6 liters per minute https://sustainabilityinfo.com/water/how-much-water-does-a-faucet-use/  
  3. Number of times a person is waiting a day for water to get hot in a shower is estimated to be 1 https://energysavingtrust.org.uk/sites/default/files/reports/AtHomewithWater(7).pdf  
  4. Number of listers wasted in the shower each time is estimated to be 5 liters with a shower head having a flow of 15 liters per minute https://sustainabilityinfo.com/water/how-much-water-does-a-faucet-use/  
  5. According to the research organisation PRB the average number of people living in a household in Europe is 2,4. Rounded up this gives an average of 3 persons per household.
    https://www.prb.org/international/indicator/hh-size-av/map/country/
  6. Waiting time for hot water is estimated to be 20 seconds each time.  
  7. Length of the pipe from the water source/heater to the faucet and shower head is estimated to 20 meters 
  8. The bathtub size is estimated at 250 liters
    https://www.badeloftusa.com/ideas/how-much-does-bathtub-hold/

 

Sources: 

Energy Saving Trust (2013) "Water at home - The biggest ever review of domestic water use in Great Britain"
https://energysavingtrust.org.uk/sites/default/files/reports/AtHomewithWater(7).pdf (1, 3) 

Sustainability Info (2021) "How much Water does a Faucet Use
https://sustainabilityinfo.com/water/how-much-water-does-a-faucet-use/ (2, 4) 

PRB (2020) PRB’s World Population Data Sheet "Average household size" 
https://www.prb.org/international/indicator/hh-size-av/map/country/ (5)

Badeloft (2021) "How Many Gallons Does a Bathtub Hold?"
https://www.badeloftusa.com/ideas/how-much-does-bathtub-hold/ (8) 

 

Estimated savings:  

Replacing a UPS 6m, speed III with a new HWR pump from Grundfos 

Old UPS 6m - speed III - Watt use: 90W - Time running a day: 24 hours* - Watt use a day: 90W 

New COMFORT BASIC - Watt use: 7W - Time running a day: 24 hours* - Watt use a day: 7W - Savings: 92% 

New COMFORT DT - Watt use: 7W - Time running a day: 10,5 hours** - Watt use a day: 3W - Savings: 97% 

New COMFORT AUTOADAPT - Watt use: 7W - Time running a day: 2,5 hours - Watt use a day: 0,7W - Savings: 99% 

New ALPHA N 25-60 180  - speed II - Watt use: 28W - Time running a day: 24 hours* - Watt use a day: 28W - Savings: 69% 

New UPS N 20-60-180 - speed II - Watt use: 70W - Time running a day: 24 hours* - Watt use a day: 70W - Savings: 22% 

* With no external timer installed 

** COMFORT DIGITAL TIMER has a factory default setting where 21 enabled 30 minutes time slots are activated 

 

Supporting facts: 

Eco Friendly Habits (2021) "Water Waste Facts: Stats About Water Consumption & Usage"
https://www.ecofriendlyhabits.com/water-wasting-facts/  

Energy Efficiency Standards Group, Energy Analysis and Environmental Impacts Division (2011) "Water and Energy Wasted During Residential Shower Events: Findings from a Pilot Field Study of Hot Water Distribution Systems"
https://energyanalysis.lbl.gov/publications/water-and-energy-wasted-during

Energy Efficiency Standards Group, Energy Analysis and Environmental Impacts Division (2011) "Water and Energy Wasted During Residential Shower Events: Findings from a Pilot Field Study of Hot Water Distribution Systems"
https://eta-publications.lbl.gov/sites/default/files/water_and_energy_wasted_during_residential_shower_events_findings_from_a_pilot_field_study_of_hot_water_distribution_systems_lbnl-5115e.pdf  

Better Pressure Boosting Systems 

 

Article page: LACK OF WATER PRESSURE OR NOISY BOOSTING SYSTEM

Decrease sound level 6 dB(A):  Calculation from Patrick Glibert, Lead Sound & Vibration Engineer, Grundfos Sound Lab Denmark 

Home Applicances sound level: https://www.nonoise.org/library/household/index.htm

Article page: COMPLICATED SELECTION, SIZING OR INSTALLATIONS

Assumption
4 hours of lost time is an estimation of extra time needed for the installer to solve issue from having to drive back and get the right components from the wholesaler, warehouse and finalise the installation.