Daily Home Renovation Tips

We have discussed this so-simple-why-has-it-not-been-invented-before water heating conservation device known as the DHWR in prior posts:

ecoENERGY Report - Part 7 - Recommendations

ecoENERGY Report - Follow-up - Drain Water Heat Recovery (DWHR) Device

As a result of these posts, I received several follow-up questions as if I was some type of expert. I am not. So, I contacted Andre Cayer of Watercycles Energy Recovery, Inc. who provided answers to the following questions / comments [which have been edited by myself for brevity]. We are appreciative of Andre for taking the time out of his very busy day to add clarity:

Question / Comment #1:

Answer:

The only real issue is one of pressure loss. Because the incoming fresh water is being heated by the DWHR device to just above room temperature, there is very little energy loss. I do not consider 8 feet away very far. I do consider 6 feet to be very close. 

Question #2:

Will the DHWR warm all of the fresh coming into the house? I would think that residents of the home would still want cold water coming out of their cold water taps.

Answer:

The DHWR device will not impact the temperature of the cold water in the house in any manner as the only cold water that will enter the DWHR device will be the water that was routed to the hot water heater.

Question #3:
What is the risk that the grey water will eventually start to mix with the fresh water after say 20 years or so or due to product manufacturing defect? What tests have been done on the design and / or quality control steps during the actual manufacturing to guard against this? 

Answer:

There is almost no chance for the grey (i.e. used) water to mix (contaminate) the fresh water. The fresh water is under pressure (50-80 psi depending on your area) entering the home and if there was a leak for whatever reason, the fresh water would leak out to the grey.

That said, due to the low volumes and lack of pressure in a drain stack in a residential setting there is very little chance of the copper wearing out and the only way for it to leak would be from a puncture. There are no seams or connections under the coil. Type M copper water line is acceptable in many provinces but we use Type L which is sufficient for most commercial applications and thicker than Type M.

Question #4:

Would there be any advantage to wrapping insulation around the outside of the DWHR pipe after installation and use, i.e. use wrapping that is available for hot water tanks?

Answer:

We get this question a lot; some people really want to do it but insulation is to prevent change in temperature. When temperatures are very close there is not much change. I do not recommend it though I do believe there is a nominal value in doing so.