27
3. Turn pump off and on several times. Heater should
shut off immediately. If it does not, repeat the
above steps.
Two-Speed Pumps
In some cases, the flow on the low-speed is insuffi-
cient to operate the heater. This is apparent when the
water pressure switch cannot be further adjusted or if
the heater makes banging noises or shuts off on high
limit. In these cases, the pump must be run at high
speed when heating the water.
Pilot Safety
The heater employs a pilot safety which closes the
main gas valve within 8/10ths of a second whenever
the pilot flame is interrupted. The pilot flame is auto-
matically lit when the device is powered. The heater
performs its own safety check and opens the main
valve only after the pilot is proven to be lit.
Flame Roll-Out Safety Switch
NOTE:
If heater is installed outside of the limits
shown, a higher pressure rated 11 psi (76 kPa)
switch may be used. A flow switch, mounted and
wired adjacent to the heater, may be used in place of
the factory mounted pressure switch. See Illustrated
Parts List for 11 psi (76 kPa) water pressure switch.
CAUTION:
Do not operate the heater without the
function of a properly adjusted water pressure switch
or flow switch.
Fig. 24: Flame Roll-Out Safety Switch
High Limits
The heater is equipped with two automatic high limits.
Both are located in the In/Out header. Both are set to
open at 135°F (57
°
C).
High Limit Removal
1. Shut off main electrical power switch to heater.
2. Remove rear In/Out inspection panel.
3. Remove defective high limit and replace with a
new high limit.
4. Replace inspection panel.
NOTE:
An erratic high limit is often characteristic of
an internal heat exchanger problem, e.g. scale build-
up, defective bypass. Refer to Troubleshooting
section.
Fig. 25: High Limit Switch
Heaters are equipped with a thermal cutoff device to
prevent flame roll-out in the event the heat exchanger
becomes blocked. This is a "single-use" type fusible
link or thermal fuse, that must be replaced when dis-
abled by an over-temperature condition, caused by
excessive restriction in the heat exchanger flue pas-
sage, roll-out, high winds, etc.
Summary of Contents for 106
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