ntent.
Aqua Therm 1
FIRST CO. - P.O. BOX 270969 - DALLAS, TEXAS 75227 - Ph. (214) 388-5751 - Fax (214) 388-2255 - www.firstco.com
I
NSTALLATION

AND
A
PPLICATION
M
ANUAL
FOR
A
QUA
T
HERM
C
OMBO
H
EATERS
Aqua Therm
®
® 2
Page
Introduction
3
Sequence of Operation
3
General Description:
Air handler cabinet
3
Heating and cooling coils
3
Add-on hot water coil
3
Circulating pump
3
Flow control module
3
Check valve
3
Air purge valve
4
Blower door safety switch
4
Water heater
4
Boiler
4
Accessories:
Thermostat
4
Horizontal drain pans
4
Freeze protector
4
Equipment Sizing:
Condensing unit
4
Air handler
4
Water heater
5
Installation:
Duct work
5
Electrical
5
Water piping
6
1. Material
6
2. Solder connections
6
3. Insulation
6
4. Length
6
5. Shut-off valves
6
6. Piping connections
6,8-10
Air handler
6
Flow control module
6
Water heater
6
Multiple water heaters
7
Anti-scald valve
7
Start-up Procedure (heating cycle)
7
Troubleshooting
12
Table of Contents 3
Add - on hot water coil: First Co. HWC series add-
on hot water coils are designed to be installed in either
existing or new duct work and operate in conjunction
with the existing fan motor to provide complete or
supplemental space heating from a gas or oil - fired
water heater. These coils are completely cased and
utilize the separate flow control module which can
be installed at the water heater for easy access and
service (see flow control module).
Circulating pump: All circulating pumps circulate
water at a rate of 3 to 6 gallons per minute and are
either factory installed or included as part of the field
installed flow control module. These pumps are
designed to circulate a precise amount of hot water
between the water heater and air handler or add - on
coil.
Flow control module: This U.L. Listed device con-
sists of the circulating pump, check valve, air purge
valve, 6' plug - in line cord and pump relay. The
module is shipped separately with RCUA - HW, MBX-
HW and HBC - HW air handlers and HWC add - on hot
water coils. The module can be field installed any-
where in the hot water heating loop between the water
heater and hot water coil and offers the advantage of
being able to install the pump assembly in the most
appropriate location for service and maintenance.
Modules must be installed with the motor in a horizon-
tal position. Junction box should not be located
underneath the pump.
Figure 1
Check valve: A check valve is factory installed in the
hot water loop to eliminate any thermosyphoning (hot
water circulating through the heating coil) while oper-
ating in the cooling mode. The check valve is installed
within the air handler or as part of the flow control
module.
L
N
G



L
N
BLK
WHT
RED
BLK
WHT
GRN
GND
C
W





120V-1PH-60HZ
SUPPLY
JUNCTION BOX
W / RELAY
FIELD WIRING
FACTORY WIRING
24V CLASS 2 WIRING
( TO AIR HANDLER )
PUMP CONTROL
BOX
FLOW CONTROL MODULE - WIRING DIAGRAM
The
Aqua Therm®
is a First Co. air handler that
converts a properly sized gas or oil-fired water heater
into a highly efficient, dual - purpose appliance that
can heat your home as well as provide hot water for
domestic purposes.
Any properly sized water heater (for heating) and
split system type condensing unit (for cooling) will
work with First Co.
Aqua Therm®
air handlers and
are to be supplied by others. NO SPECIAL WATER
HEATER IS REQUIRED!

Aqua Therm
® air handlers are even compat-
ible with boiler systems.

Aqua Therm®
air handlers include a fan motor for
air circulation, hot water circulating pump, hot water
heating coil, air purge valve, check valve, compo-
nents for low voltage control and most include a
cooling coil for air conditioning. All components in the
water piping are approved for potable water use.
SEQUENCE OF OPERATION
(Heating mode)
When space heating is needed, the wall thermostat
energizes a small pump which circulates hot water
(135 to 140 degrees ) from the water heater to the hot
water coil in the air handler. As the fan motor forces
the cool return air from the home over the hot water
coil, the air absorbs heat from the hot water and this
warm air (about 105 to 110 degrees) is then circulated
throughout the duct system and into the home.
IMPORTANT. . . . . in most applications the water will
lose only 15 to 25 degrees in temperature while
circulating through the hot water coil and will RE-
TURN to the water heater at about 115 to 125 degrees
to be reheated.
GENERAL DESCRIPTION
Air handler cabinet: Air handlers with cabinets are
made of galvanized steel and fully insulated to reduce
noise and maximize efficiency. Throwaway filters are
factory installed in most air handlers.
Heating and cooling coils: All heating and cooling
coils are made of copper tubes with mechanically
bonded aluminum fins for maximum heat transfer.
Manual air vents are included on all hot water coils.
Cooling coils have either piston - type metering de-
vices or field installed expansion valves. Primary and
secondary condensate drain connections are pro-
vided on each cooling coil. All primary connections
are 3/4 inch MPT. 4
INSULATING
TAPE
FREEZE
PROTECTOR
WIRE
TIE
24 VOLT
LEADS
HOT WATER COIL
Air purge valve: All air handlers and / or flow control
modules include a large manual air purge valve to
facilitate air removal from the heating loop prior to
system start - up. When the air handler and water
heater are piped according to First Co. instructions,
the air in the hot water coil and piping will only need to
be removed before initial start - up or after air has
gotten into the system because of a plumbing leak or
break in a water main. This can be accomplished by
using the 2 - step process described under start -up
procedure.
Blower delay relay: HWF series air handlers include
a blower delay relay that allows the circulating pump
to operate on a call for heat for 20 to 45 seconds
before the fan motor comes on to deliver warm air
quicker when the heating system starts. This relay
also keeps the fan motor on for 20 to 45 seconds after
the thermostat is satisfied in the heating cycle to
maximize the efficiency of the heating coil.
Flue gas safety switch: All "Q" type air handlers, as
well as the MAX-HW,MBX-HW, and HWF series air
handlers, include a factory installed flue gas safety
switch. When the blower door is removed for any
reason the air handler fan motor will not operate. This
is especially important when the water heater is in the
same closet as the air handler because products of
combustion from the water heater flue pipe could be
circulated throughout the duct system if the air han-
dler were allowed to operate without the door in place.
Water Heater: Any properly sized gas or oil - fired
water heater will work ( even direct vent or powered
vent types ). Electric water heaters are not recom-
mended because of their slow recovery rate. Water
heater warranties are not affected by this system
since no modification of the water heater is neces-
sary. Selection of higher efficiency water heaters will
result in even greater savings.
Boiler: Most First Co.
Aqua Therm®
air handlers
and add - on hot water coils are also compatible with
boilers and instantaneous water heaters. Please
contact the factory for assistance in selecting the
proper equipment for these applications. (See Page
11 for wiring diagram of multiple air handlers.)
ACCESSORIES
Thermostat: All "Q" type air handlers will operate
with any standard 24 volt heat / cool or heat pump
thermostat.
All other air handlers require a 24 volt thermostat
that energizes the fan motor on a requirement for
cooling and heating. This is commonly called an
"electric heat" thermostat. CAUTION . . . . . a gas
furnace thermostat will NOT work with these units
because the fan motor will not come on when the
thermostat calls for heat.
Normal heat anticipator setting should be 0.3 to 0.4.
If a set-back thermostat is used, allow extra time for
recovery in the morning.
Horizontal drain pans: These field installed kits
allow the following air handlers to be converted to
horizontal position with air flow from right to left:
#935-1 fits 2 through 3 ton VAQ
#935-2 fits 3.5 and 4 ton VAQ
(MAQ,MBQ,MAX-HW and MBX-HW have built in
horiz. drain pans)
Freeze protector: Kit number 941-1 can be field
installed on any
Aqua Therm®
air handler or add -on
coil and is highly recommended when the air handler
or hot water coil is installed in a space that may be
subjected to freezing temperatures such as in an attic
or crawl space. The sensor attaches to the hot water
coil and is wired to R and W in the low voltage circuit.
If for any reason the temperature of the hot water coil
falls below 38 degrees the sensor will bring on the
pump to circulate hot water. This will occur even if the
thermostat is in the "off" position.
Figure 2
EQUIPMENT SIZING
Condensing unit: The condensing unit should be
sized to meet the calculated heat gain according to an
approved heat gain formula.
Air handler: Select an air handler with a heating
BTUH that exceeds the structure's calculated heat
loss and a cooling coil matched to the tonnage size of
the outdoor condensing unit.
Special note . . . . . the actual heating output of the
air