Enertech AV Series - Designing the System

Enertech Global, LLC 15
AV : MD/ME - Rev. A Models
Installaon and Operaons Manual
Secon 3: Introducon & Operaonal Consideraons
Designing the System
Enertech strongly recommends using an approved zone
control (HBX or EWC) to provide the most compable
operaon with the Indoor Module. Although other control
systems will work, Enertech Technical Services personnel are
most familiar with the approved controls. Other controls may
be dicult to support should troubleshoong be needed.

According to the Water Research Foundaon, the average
American shower uses approximately 15.8 gallons and lasts
for 7.8 minutes at an average ow rate of 2.1 gpm. Depending
upon local regulaons, shower heads may be available with
1.8, 2.0, or 2.5 gpm ow rates. The state of California, for
example limits the ow rate to 1.8 gpm, as of July 2018. In
some cases ow restrictors can be removed/modied or
mulple shower heads may allow signicantly more water
usage.
Following are some consideraons when determining indirect
water heater choice, as well as the need for a second water
heater:
EAV Capacity: The EAV unit has much higher capacity than
a standard electric or gas water heater, although the indirect
water heater storage is for “load water”, not potable water.
Therefore, the Turbomax indirect water heater operates more
like an instantaneous water heater than a standard water
heater. Based upon Enertech lab tesng, draws of 5 gpm for a
sustained period from the water heater will cause the supply
temperature at the xture to drop.
Large Usage: In a typical residenal applicaon, a second
water heater is not necessary for capacity reasons. In large
usage applicaons (spa tubs and mul-head showers), a
second water heater is necessary to meet the hot water needs
of the customer. A gas or electric water heater can be added
to the system to cover these needs. A review of the required
gpm and gallons of hot water will be required to size the tank.
Keep in mind that mulple shower heads could legally use as
much as 10 gpm.
Redundancy: A second water heater will provide some
redundancy to the system if there is a pump failure in the heat
pump or some other issue not allowing the heat pump to run.

hot water.
Note: Based upon the consideraons above, Enertech
recommends a second water heater for all
EAV installaons. It is a relavely inexpensive addion that
provides many advantages.

Tank selecon is based upon the number of bathrooms
(types of showers and tubs), dishwashers, washing machines,
and number of people in the home. Enertech oers two
selecons, a 45 gallon indirect tank and a 65 gallon indirect
tank. Typically, a 45 gallon tank will handle two bathrooms
with water ecient xtures, one dishwasher, and one
automac clothes washer. A 65 gallon tank will handle 3-1/2
bathrooms with water ecient xtures, one dishwasher, and
one automac clothes washer. If the home has been idened
as a large usage applicaon (see “Large Usage”, above), a
second water heater in series with the Turbomax indirect
water heater is required. Even applicaons that are not “Large
Usage” will benet from a backup water heater for mes
when the outdoor temperature is very cold, during defrost
cycle, or for emergency use.

The EME model Indoor Module has an internal 9kW
immersion heater that can be used for supplemenng the
heat pump capacity for hydronic heang and/or DHW heang.
Depending upon the applicaon, either the internal heater or
external backup may make more sense. If addional heang
capacity is needed, a determinaon should be made based
upon type of heang required. For example, in most cases, a
backup electric heater is installed in the fan coil. Since the fan
coil is required for cooling anyway, it can be used for backup
or for emergency heat. For DHW, a second water heater
can provide both backup heang capacity and emergency
DHW heang. The advantage of the internal electric heat is
that duct heaters and second water heaters are not needed.
However, if a pump fails, the internal electric heat cannot
operate. Each applicaon must be evaluated individually
to ensure that the type of backup ts the requirements.
Installaon diagrams in this IOM show the typical connecons
used for addional heang back up sources or dual fuel
applicaons. Enertech recommends a second water heater
and electric heat in the fan coil, ulizing the internal electric
heat as oponal.

The EMD model Indoor Module has connecons for an
external boiler that can be used for supplemenng the heat
pump capacity for hydronic heang and/or DHW heang. For
DHW, a second water heater or a combi boiler can provide
both backup heang capacity and emergency DHW heang.
Enertech recommends a second water heater (or combi
boiler) and electric heat in the fan coil.