DRAIN WATER HEAT RECOVERY
IN A NUTSHELL
Lesson
D- How DWHR works
E- Difference in designs
F- Selecting the right size
The Process: Heat the incoming cold water with the heat energy from waste water.
The Result: Less energy required to heat ...
All DWHR units should be safety and performance certified to CSA B55.2 and CSA B55.1
Factors that determines a good DWHR d...
Factor 1 – What is the inside diameter of your drain pipe 3 or 4 inches.
Note: 99% of the time you will have a 3 inch diam...
Upcoming SlideShare
Loading in …5
×

Drain water heat recovery in a nutshell 102. How it works, different designs, residential size selection

423 views

Published on

Drain Water Heat Recovery 102 - How does it work? What are the different designs and what do I look for? What size do I select?

Published in: Education
  • Be the first to comment

  • Be the first to like this

Drain water heat recovery in a nutshell 102. How it works, different designs, residential size selection

  1. 1. DRAIN WATER HEAT RECOVERY IN A NUTSHELL Lesson D- How DWHR works E- Difference in designs F- Selecting the right size
  2. 2. The Process: Heat the incoming cold water with the heat energy from waste water. The Result: Less energy required to heat water and 3x more shower time Life expectancy: Thicker coil walls, larger coil diameter = longer life. 50+ years
  3. 3. All DWHR units should be safety and performance certified to CSA B55.2 and CSA B55.1 Factors that determines a good DWHR design 1) Length versus efficiency – you should aim between 36 and 48 inches with a rating of 1% efficiency per inch. Example: 42 inches = 42% efficient 2) Pressure drop – Anything below 4 psi rating is good. 3) Number of braze joints – The more joints, the more potential problems with leakage. Avoiding brazed or soldered coil joints in design selection. A single ¾” coil design with no interruptions in cold water flow should be your first choice for a long trouble free unit. 4) Diameter and thickness of the coil walls – Thicker walls means longer service life, larger diameter walls means less chance of blockage and reduction of performance over time.
  4. 4. Factor 1 – What is the inside diameter of your drain pipe 3 or 4 inches. Note: 99% of the time you will have a 3 inch diameter pipe. Factor 2 – Do you have any height restrictions? Call the manufacturer for help. Factor 3 – Coil joint is ¾” if preheating to the hot water tank. Factor 4 – What do you want as a payback period and return on investment. – use DHWR course 101 and try the online calculators to help. Remember – Unless comparing models from the same manufacturer, longer is not necessary better. Always compare length versus kW ratings. Example: Manufacturer A has a 58 inch long unit that has a lower kW rating than manufacturers B’s 40 inch unit. Length = deception

×