COMBO HEATING
This section serves as a guide for the installation and use
of "Combo" heating systems utilizing a domestic water
heater that has been speci
fi
cally approved for such use. It is
written for those knowledgeable in the required trades and
professionals 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
The following requirements must be met for the installation of
Combo Heating Systems:
All components used for the distribution of water in the
heating loop must be suitable for potable water. These
include all piping, fittings, solder and fluxes, pumps for
circulation of water, valves, etc.
The water heater must not be connected to a hydronic
heating system that has been used previously.
No boiler treatment chemicals of any kind shall be intro-
duced into the system.
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 per-
formed in accordance with good engineering practice
such as "ASHRAE Handbooks", HRAI's Unified Combo
Guidelines, "Hydronics Institute Manuals", CSA-B149.1,
ANSI Z223.1, CSA F280, National/Provincial Building
Codes, CSA C22.1, ANSI, CSA B51 and/or codes having
jurisdiction.
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 identified for this pur-
pose.
All piping between the water heater and the air handler or
hydronic baseboard loop must be adequately insulated to
reduce heat loss.
If the local jurisdiction requires a back-flow preventer in
the cold water line, an expansion tank of adequate size
must be installed.
"Combo" Heating Systems require higher water tem-
peratures 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
Figures 42 & 43).
Installation
The heating mode may be one of the following options:
A.
A fan coil/air handler (Figure 42).
B.
A hydronic baseboard (
fi
nned tube) loop/In
fl
oor
heating (Figure 43).
The following is a list of requirements for the installation of
option A or B.
Install shut-off valves and unions so that the water heater
can be isolated from the heating module should servicing
of the water heater become necessary.
1.
2.
3.
4.
5.
6.
7.
8.
1.
Install a drain valve at the lowest point of the heating loop
so that water can be drained from the heating module
without affecting the water heater.
If the air handler does not have a venting means at the
highest point of the piping arrangement, install an air
bleed at the highest point of the plumbing arrangement.
A properly-sized thermal expansion tank should be
installed on all closed systems to control the harmful
effects of thermal expansion. Contact a plumbing service
agency or your retail supplier regarding the installation of
a thermal expansion tank.
WATER
HEATER
8 in TO 12 in
MAX.
HOT
OUTLET
EXPANSION TANK
(OPTIONAL)
MIXING
VALVE
COLD
INLET
CHECK VALVE
(IF USED
REQUIRES
EXPANSION
TANK)
COLD
SUPPLY
HOSE BIB
(OPTIONAL)
FLOW
CONTROL
SUPPLY
RETURN
CHECK
VALVE
EXTERNAL
CIRCULATOR
AIR HANDLER
HOT WATER
TO HOUSE
FIXTURE
C
H
M
INTERNAL
CIRCULATOR
DRAIN/PURGE
VALVE
Figure 42
WATER
HEATER
8 in TO 12 in
MAX.
HOT
OUTLET
EXPANSION TANK
(OPTIONAL)
MIXING
VALVE
COLD
INLET
CHECK VALVE
(IF USED
REQUIRES
EXPANSION
TANK)
COLD
SUPPLY
HOSE BIB
(OPTIONAL)
FLOW
CONTROL
SUPPLY
RETURN
CHECK
VALVE
EXTERNAL
CIRCULATOR
HOT WATER
TO HOUSE
FIXTURE
C
H
M
HYDRONIC
BASEBOARDS
(SERIES
CONNECTED
SHOWN)
Figure 43
2.
3.
4.
– 31 –
