lp-770 Rev. 000 Rel. 000 Date 6.21.21
10
Part 3 - Piping
When lling the water heater, open a hot water tap to release air in
the tank and piping. Failure to do so could lead to improper water
heater operation and damage to components.
E. Boiler Connections
Use a 3/4” nominal minimum pipe size when piping with zone
valves or circulators.
On the water heater, the boiler supply connects to the outlet of the
circulator. The circulator inlet is to be connected to the hot outlet
side of the boiler. Be sure that the arrow on the circulator is facing
the correct ow direction. (See pressure drop sizing for circulator,
this manual.) On the tank, the boiler return connects to the return
side of the boiler. The return(s) from heating loop(s) should have
a ow check or swing check valve installed before the return pipe
from the tank.
The water heater heat exchanger cannot be used with non-barrier
radiant pipe systems. Use with closed loop boiler systems only.
F. Hot Water Outlet
Dielectric ttings must be used on water connections.
Exercise caution when soldering water heater connections, as
outlet and inlet dip tubes are plastic.
Failure to follow the instructions in this section WILL VOID the
warranty and may result in property damage, severe personal injury,
or death.
Do not apply a torch within 12” of the water heater. If sweat
connections are used, sweat tubing to the adapter before tting
adapter to the water connections on the heater. Damages due to
improper installation practices ARE NOT covered by warranty.
A. General Plumbing Guidelines
Use two wrenches when tightening water piping at heater. Use one
wrench to prevent the heater inlet or outlet line from turning. Failure
to prevent piping connections from turning could cause damage to
heater components.
The building piping system must meet or exceed the piping
requirements in this manual.
Plumbing of this appliance should only be done by a qualied, licensed
plumber in accordance with all local plumbing codes.
Use both thread tape and pipe dope to connect an NPT male X 3/4”
(minimum) pipe adapter. A shut-o valve between the hot water
supply and tank outlet is recommended for ease of service.
Installing a heat trap in the domestic hot water outlet will improve
energy eciency and reduce piping heat loss.
All plumbing must be in accordance with the requirements of the
authority having jurisdiction.
• Use both thread tape and pipe dope on all mechanical con-
nections.
• Zone valve (if used) and circulator must be sized to provide
minimum ow rate specied in the table to the right, Flow
Specications. Use 1 inch nominal copper tubing for ows
greater than 7 GPM between the boiler and heat exchanger.
See the tables on Friction Loss. Point of emphasis: Using a
zone valve without a full bore may cause high pressure drop
which will adversely aect performance. Use extreme care
when selecting zone valve.
• All piping must be adequately supported.
• Allow for thermal expansion.
• Dielectric Unions (recommended) ‐ used to electrically isolate
the tank from the connected domestic water piping. This
helps to minimize the possibility of corrosion damage.
Model
Recommended
Flow Rate
Heat Exchanger
Pressure Drop
(ft. hd.)
Domestic Water
Connection
Sizes
20 5 GPM 1.2
3/4”
32 8 GPM 3.8
40
12 GPM
7.6
50 8.8
Table 10 - Flow Specications
Tubing Type Flow Rate 10 GPM Flow Rate 15 GPM
Type K 3.1 psi 6.5 psi
Type L 2.7 psi 5.7 psi
Type M 2.3 psi 4.7 psi
Table 11 - Friction Loss per 100’ of Tubing (psi)
Fitting Wrought Cast
90
o
Elbow 1 4
45
o
Elbow 1 2
Tee - Run 1/2 1/2
Tee - Branch 3 5
Long Radius 90
o
Elbow 2 -
180
o
Bend 2 -
Gate Valve - 1
Table 12 - Friction Loss Allowance for Copper Fittings (ft. of Tubing)
C. Potable Expansion Tank
A potable hot water expansion tank may be required to oset heated
water expansion. If there is a back ow preventer or any other type
of no return or check valve in the system a thermal expansion tank IS
MANDATORY. The expansion tank must be sized for the entire water
volume of the hot water system. A weeping relief valve indicates the
need for an expansion tank. See the Typical Expansion Tank example in
the Piping section for details.
B. Backow Preventer
Use a backow preventer specically designed for water heater
installations. This valve should be installed on the cold water ll supply
line per local codes.
D. Pressure Drop Sizing For Circulator
The boiler circulator ow rate must meet the requirements found
in the pressure drop sizing chart. The chart represents the pipe run,
water heater, and heat exchanger ONLY and does not include any ow
checks, zone valves, or friction loss through the boiler. That resistance
must be added to the value found in the following chart.
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