John Wood Power Direct Vent (ENERGY STAR) - Manual (Page 29)

VII) COMBO HEATING
WARNING
Keep the area around the heater clear and
unobstructed.
This section serves as a guide for the installation and use of
“Combo” heating systems utilizing a domestic water heater
that has been specifically approved for such use. It is written
for those knowledgeable in the required trades and profes-
sionals involved in the design and installation of Combo
Heating Systems.
It is the responsibility of the installer/designer to follow
all applicable codes to ensure the effectiveness and
safety of the installation.
System Requirements
CAUTION:
Keep safety your first priority. Take all pre-
cautions to avoid creating a fire, health or
safety hazard.
The following requirements must be met for the installation
of Combo Heating Systems:
1. All components used for the distribution of water in the
heating loop must be suitable for potable water. These
include all piping, fi ttings, solder and fl uxes, pumps for
circulation of water, valves, etc.
2. The water heater must not be connected to a hydronic
heating system that has been used previously.
3. No boiler treatment chemicals of any kind shall be
introduced into the system.
4. The Combo System components must be selected
and sized to meet and maintain the total calculated
demands for both domestic service hot water and space
heating requirement. The sizing and installation must be
performed in accordance with good engineering practice
such as “ASHRAE Handbooks”, HRAI, “Hydronics
Institute Manuals”, CSA-B149.1, NFPA 54, ANSI
Z223.1, CSA F280, National/Provincial Building Codes,
CSA C22.1, ANSI/NFPA 70, CSA B51 and/or codes
having jurisdiction.
5. The air handler (fan coil) and/or the circulating pump
in a baseboard hydronic loop will require a dedicated
120V circuit. This must be provided and identifi ed for
this purpose.
6. All piping between the water heater and the air handler or
hydronic baseboard loop must be adequately insulated
to reduce heat loss.
7. If the local jurisdiction requires a back-fl ow preventer in
the cold water line, an expansion tank of adequate size
must be installed.
8. “Combo” Heating Systems require higher water
temperatures than other applications. When the system
is used to supply water for Combo Heating applications, a
means, such as mixing valve, must be installed to temper
the water in order to reduce scald hazard potential (see
Figure 24 & Figure 25).
– 29 –