Maximum Vent Length; Freeze Protection - Rinnai REU-VC2837FFU-US Installation And Operation Manual

Maximum vent length

(indoor models only)
1. Determine the number of 90 degree elbows in
the vent system. (Two 45 degree elbows count as
one 90 degree elbow.)
2. Refer to the table to find the maximum vent
length based on the number of elbows.
Number of
90° Elbows
0
1
2
3
4
5
6
3. Adjust SW 1 in DIPSW 1 (tan switches) if required
by the applicable note.
 If the length is greater than 21 ft (6.4 m) then
move SW 1 in DIPSW 1 to OFF.
 If the length is greater than 15 ft (4.6 m) then
move SW 1 in DIPSW 1 to OFF.
 If the length is greater than 9 ft (2.7 m) then move
SW 1 in DIPSW 1 to OFF.
 Move SW 1 in DIPSW 1 to OFF.
Example: If you have one elbow then your maximum
vent length is 35 feet (10.7 m). If your
actual length is greater than 15 ft (4.6 m)
then move SW 1 in DIPSW 1 to OFF.
NOTICE
If you have a longer vent length (see above), SW 1 in
DIPSW 1 is required to be in the OFF position. This
ensures the water heater will run properly. Blocked
flue diagnostic codes and shutdowns may result if
SW 1 in DIPSW 1 is not in the correct position.
Maximum vent length
41 ft (12.5 m) 
35 ft (10.7 m) 
29 ft (8.8 m) 
23 ft (7.0 m) 
17 ft (5.2 m) 
11 ft (3.4 m) 
5 ft (1.5 m) 

Freeze Protection

Make sure that in case of freezing weather that the
water heater and its water lines are protected to
prevent freezing. Damage due to freezing is not
covered by the warranty.
Loss of freeze protection may result in water damage
from a burst heat exchanger or water lines.
With electrical power and gas supplied, the water
heater will not freeze when the outside air
temperature is as cold as –22°F (-30°C) for indoor
models or is as cold as –4°F (-20°C) for outdoor
models, when protected from direct wind exposure.
Because of the "wind-chill" effect, any wind or
circulation of the air on the unit will reduce its ability
to freeze protect.
The unit may be drained manually. However, it is
highly recommended that:

drain down solenoid valves are installed that will
automatically drain the unit if power is lost.
These are available in a kit, 104000059.

a surge protector with terminals is installed which
allows the solenoid valves to operate if the unit is
disabled due to a diagnostic code. This is
available as 104000057.
In addition, the solenoid valves should be connected
electrically to a surge protector with terminals. This
allows the solenoid valves to operate if the water
heater is disabled due to a diagnostic code.
The freeze protection features will not prevent the
external piping from freezing. It is recommended that
hot and cold water pipes are insulated. Pipe cover
enclosures may be packed with insulation for added
freeze protection.
In the event of a power failure and/or gas
interruption at temperatures below freezing the
water heater should be drained of all water to
prevent freezing damage. In addition, drain the
condensate trap and drain line.
Value Series Manual 11