Specifications
Part number 550-100-090/0809
37
g a s -f i r e d w a t e r b o i l e r — Boiler Manual
BASIC INSTALLATION
Startup — final checks (continued)
Model 399 — Throttle screw location Figure 39
(ONLY for use by a qualied technician,
using calibrated combustion test
instruments)
grommet into the flue pipe, then insert the probe into the rubber
grommet.
You must replace the flue gas temperature sensor to
prevent flue gas spillage into the boiler enclosure. Failure
to comply could result in severe personal injury, death
or substantial property damage.
Ultra-399 propane conversion & start-up
Ultra-399 boilers are converted for propane by adjustment of the gas
valve throttle screw (no orifice change) — Figure 39. This must only
be done while using a combustion analyzer.
Turn the gas valve throttle screw clockwise 5 turns before starting 1.
the boiler. Then follow the start-up procedure on page 36.
Once the boiler is started, make slight adjustments to the throttle 2.
screw to obtain a CO
2
of 10.2% with CO less than 100 ppm air
free. (Allow the combustion analyzer’s reading to stabilize before
making adjustments.)
After the boiler has been set up correctly, the conversion is com-3.
plete. Fill in the information on the propane conversion label and
attach the label to the boiler rating plate.
Throttle screw adjustment procedure
See Figure 37, page 36, Figure 38, page 36, or Figure 39, page 37 for
location of the throttle screw.
DO NOT attempt to adjust the throttle screw unless by
a qualified technician, and with the use of calibrated
combustion test instruments. Adjust the throttle screw
only as needed to meet the combustion values given in
Figure 40.
This procedure is only necessary when specified elsewhere in this 1.
manual or when combustion tests indicate the need, as explained
under “ Check flame & combustion with instruments,
page 36.”
Boiler behavior that might indicate a need to check combustion 2.
values at high fire (as per page 36) to verify boiler is in adjustment
include: difficulty igniting, poor flame stability at low fire, combus-
tion noise or high carbon monoxide values.
Combustion readings must be taken at both high fire and low fire. 3.
DO NOT attempt an adjustment of the throttle screw at low fire.
Just check the combustion values.
Use the U-Control display to navigate to Manual test mode (see 4.
Figure 102, page 86) and force the firing rate to MAX (high fire).
After the boiler has had time to stabilize, take a CO
2
reading.
If the COa.
2
is HIGH, turn the throttle screw CLOCKWISE to
lower the input. Allow the boiler to stabilize and take another
reading. Continue until the desired CO
2
value is achieved.
If the COb.
2
is LOW, turn the throttle screw COUNTERCLOCK-
WISE to increase the input. Allow the boiler to stabilize and
take another reading. Continue until the desired CO
2
value is
achieved.
Lock the boiler into low fire. Check the combustion readings. If 5.
results are acceptable at low fire, verify high fire readings again.
Restore firing rate to AUTO.
Consult your local Weil-McLain representative if acceptable results 6.
cannot be obtained for both high and low fire.
Adjust and test boiler controls
Follow instructions in this manual to set and verify 1.
operation of the boiler controls.
Figure 40 Acceptable CO2 and CO values (CO2 values
must be within 1.0% of the values listed)
Boiler Fuel
High re Low re
%CO
2
CO ppm %CO
2
CO ppm
Ultra-80
NG 8.6 < 60 7.8 < 60
LP 9.6 < 60 8.6 < 60
Ultra-105
NG 9.0 < 60 8.4 < 60
LP 10.1 < 60 9.2 < 60
Ultra-155
NG 9.0 < 60 8.0 < 60
LP 10.0 < 60 8.5 < 60
Ultra-230
NG 9.0 < 60 8.0 < 60
LP 10.0 < 60 9.0 < 60
Ultra-299
NG 9.0 < 60 8.0 < 60
LP 10.0 < 60 9.0 < 60
Ultra-399
NG 9.2 < 100 8.4 < 60
LP 10.2 < 100 10.0 < 60
The values above are with the boiler front door removed.
Values will typically increase about 0.2% once the door is
reinstalled.
The values above are for altitudes up to 5,500 feet. For higher
altitudes, CO
2
may be slightly lower and CO slightly higher.