Drainwater
heat recovery (DHR) is a very simple and effective means to recapture
heat that is otherwise lost to the drain. There are many ways to save
on water heating costs but a DHR unit is definitely the most cost effective.
Imagine it as your shower preheating itself. The falling drainwater passes
through a double walled heat exchanger whilst the cold water destined
for the water heater and shower is also routed to the heat exchanger to
absorb most of that valuable heat. Through the DHR the cold water temperature
is raised 10+ degrees C meaning the water heater runs for a shorter amount
of time.
Lower water heating costs -
up to 40%
Extend Hot water Capacity
Reduce Carbon footprint - up to 1000kg
Increase life of water heater
Zero maintenance, self cleaning and no moving parts
Long lifespan -- all copper construction
Merlyn
recommends and installs only the Power-Pipe® brand DHR units for their
superior design, durability and that they're locally made in Waterloo,
Ontario.
Downloads
Guide
to retrofitting a DHR unit into your home
Power-Pipe
price list
Frequently
Asked Questions
How
much could I save?
How do I know it works?
How would I know if a Power-Pipe® can be installed
in my home?
Does the device save me on all hot water draws?
What if I have multiple drains?
Can I install the unit myself?
How
much could I save?
Being
an efficiency measure, logically the more hot water you use the more
you save with a DHR. Also, the higher percentage of hot water use taken
by showers in your home the more you will save. Efficiency of the DHR
units varies by length, ranging from 15-75%, 40-50% being most common.
So, if the showers in your house represent 50-70% of your hot water
and the DHR is saving 40-60% of that load, the savings are in the range
of 20-40% of your hot water costs.
How
do I know it works?
The
energy savings of a drainwater heat recovery unit have been verified
by Natural Resources Canada and are included as a grant worthy option
under the ecoENERGY for Homes program. Some utilities also support the
installation of such units with on-bill credits and other incentives.
Once
you have one installed, you can feel for yourself the temperature increase
across the heat exchanger when someone is having a shower. That temperature
difference (15-25C) is heat your water heater doesn't have to produce.
How
would I know if a Power-Pipe® can be installed in my home?
DHR
units can be installed in most, but not all homes.
Generally
speaking, newer homes with finished basements are not likely to easily
support a DHR install. They have multiple drainstacks and are often
drywalled in bulkheads with drywalled ceilings. If you're lucky a shower
rich drainline will be located in the mechanical room right near the
softener. Side split homes are also trouble, as the showers usually
sit on the split with the drainline coming down to the basement on an
angle, not presenting much vertical height to work with.
1)
First question we ask is "Can you see your drainstack in the basement?",
if the answer is "No" then chances are slim that DHR will
be easy or feasible to install. The drainstack must be fairly easily
accessible to be cut out and replaced with the DHR
unit which is usually 48-72" long.
2)
Secondly, how much vertical, uninterrupted, drainstack is available?
The heat exchanger should only ever be installed vertically and should
be at least 36".
3)
Thirdly you must be able to route the cold water lines to the heat exchanger
and back. Cold water is usually intercepted after the softenener (or
water meter) and sent to the heat exchanger and back. Using only the
cold water feed to the water heater is also an option, however it is
slightly less efficient than having all the home's water running through
the heat exchanger.
Read
this retrofit
guide for more information.
Does
the device save me on all hot water draws?
No,
the DHR unit functions effectively when there is a simultaneous draining
of hot water and a flow of hot water. This essentially limits it to
showers, luckily enough showers represent most of the hot water use
in a house (a generally accepted estimate is 50-70% of a typical family's
hot water). When you have a sink of dishwater or a bath, you are draining
the heat without any flow of cold water to pick it up. It is true that
the small amount of water sitting in the heat exchanger will absorb
that heat and either be available for a limited time for the next hot
water draw or ooze into your house, a small savings.
DHR
units also cannot save any of the heat from showers located in the basement
because the drain is below the heat exchanger.
What
if I have multiple drains?
A
multiple drain scenario is likely in homes built after 1990 or any home
with extensive renovations/additions. The trend of master bedrooms with
ensuite bathrooms saw drains spread out around the house. As discussed
above, the DHR unit will only effectively save the energy of the showers
so those drains that carry the shower water are of interest. It may
be the case where several showers are split amongst the drains -- here
the shower that sees the most regular use should be the target. It is
still quite reasonable to install multiple DHR units however the financial
return will be lower.
Can
I install the unit myself?
Yes,
the handy homeowner can install a DHR unit without much trouble. Skills
and tools required must accommodate cutting and removal of the drainstack
(ABS/ copper / cast iron) and the plumbing work to re-route the cold
water in copper or PEX tubing.
Incentives
Prices
The
average price of a DHR unit, including installation and taxes is $950.
This
will vary depending on the unit size and ease of installation, a range
is $700 - $1200
View
the Power-Pipe® unit price
list.
|
