10
Dual Fuel Supplemental Manual
2
Start-up
Table 2A Flue Products Chart
10. Repeat the same procedure for propane gas. Reference the
Dual Fuel Switching Instructions on pages 10 and 11 of this
manual.
11. Turn the main power off to the boiler and replace the
flue temperature sensor into the flue pipe connection.
12. Place the boiler back into normal operation.
You must replace the flue gas temperature
sensor to prevent flue gas spillage into the
room. Failure to comply could result in
severe personal injury, death, or substantial
property damage.
WARNING
Gas
Valve
Natural Gas
Propane
CO
2
O
2
CO
2
O
2
1 - High 3.5% - 5.5% 11.2% - 14.8% 5.1% - 6.8% 10.5% - 13.2%
2 - High 7.8% - 8.6%
5.6% - 7.1%
9.4% - 11.0%
4.1% - 6.6%
Check flame and combustion
1. Turn the main power off to the boiler by placing
the “On/Off” switch in the OFF position.
2. Remove the flue temperature sensor from the flue
collector.
Note:
Combustion measurements will
be made at this point.
3. Turn the main power on to the boiler by placing
the “On/Off” switch in the ON position.
4. Navigate to the Service Maintenance Screen from
the Home Screen by pressing the SETUP button,
enter the installer password, and then using the
scrolling menu feature on the left side, scroll down
to the SERVICE MAINTENANCE button.
5. On the Service Maintenance Screen place heater
into Service Mode by selecting the START button,
then selecting
Set Gas Valve 1 - High
.
6. Insert the probe from a combustion analyzer into
the hole left by the removal of the flue temperature
sensor.
7. Once the heat exchanger has modulated up to
rate, measure the combustion. The values should
be in the range listed in Table 2A. CO levels
should be less than 200 ppm for a properly
installed unit. If the combustion is not within
range reference the
Troubleshooting
Section in
the Crest Service Manual for possible causes and
corrective actions.
NOTICE
A flame and combustion check
must be performed on natural gas
and then repeated on propane.
8. After
Gas Valve 1
is set, repeat the same procedure for the second
gas train by selecting
Set Gas Valve 2 - High
on the Service
Screen.
9. Once the heater analysis is complete, test the safety shutoff device
by turning the manual shutoff valve to the OFF position and
ensuring that the heater shuts down and registers an alarm. Open
the manual shutoff valve and reset the control.
Dual fuel switching instructions
1. Turn the main power off to the boiler by placing the
“On/Off” switch in the OFF position (FIG.’s 2-2A and
2-2B).
2. Using the fuel selector switch (FIG.’s 2-2A and 2-2B),
select the desired fuel.
Figure 2-2A Fuel Selector Switch - Models 2.5 - 3.5
IMG00063
NATURAL
PROPANE
DETAIL
IMG00064
MAIN POWER
SWITCH
NATURAL PERSONALITY I.D.
PROPANE PERSONALITY I.D.
FUEL SELECTION
SWITCH
