Specifications
Part number 550-100-090/0809
g a s -f i r e d w a t e r b o i l e r — Boiler Manual
42
The Gas-fired water boiler, Featuring Flexibility
Models 299 and 399
1. Cast aluminum heat exchanger
2. Heat exchanger access cover
3. Blower
The advanced blower design and air inlet silencer on Ultra boilers result
in very quiet operation.
Air enters the boiler enclosure through the air intake adapter (18), flows
through the enclosure, enters the air inlet silencer (5), then enters the
venturi (6). The blower pulls air and gas through the venturi and pushes
the mixture into the burner.
4. Gas valves and sense lines
The automatic gas valve (4a) senses the vacuum in the venturi caused by
flowing air, and allows gas to flow when power is applied. The manual gas
valve (4b) allows shutting off the gas supply for servicing or shutdown.
5. Air inlet silencer
The horn-shaped air inlet silencer significantly reduces fan noise, provid-
ing exceptionally quiet operation.
6. Venturi
When air flows through the venturi, it creates a vacuum. This vacuum
pulls gas from the gas valve. So gas will only flow if air is flowing. The
gas/air mixture enters the blower before passing on to the burner.
7. Outlet water temperature dual sensor
This sensor monitors boiler outlet water temperature. The control mod-
ule adjusts boiler firing rate so the outlet temperature is correct, based
on boiler outlet and system supply temperatures.
8. Boiler return water temperature sensor
This sensor monitors return water temperature. The control module
reduces or increases boiler input, depending on how close the return
water temperature is to the outlet water temperature.
9. Temperature and pressure gauge
10. Electronic display & buttons
The electronic display is used to configure boiler settings and monitor
boiler operation.
The buttons allow changing display mode, entering setting values, and
resetting after lockout.
11. Flue pipe adapter with internal drain
12. Burner (not shown)
Made with high-grade stainless steel construction, the burner uses pre-
mixed air and gas. The burner and control provide modulating firing.
13. Water outlet pipe (system supply)
14. Water return pipe (system return)
15. Gas connection pipe
16. U-Control Module
The U-Control
Module responds to signals from the room
thermostats, DHW aquastats (when used), boiler sensors
(boiler return, boiler supply, system return, system supply, flue
temperature, and outdoor temperature, if used). The control
module automatically adjusts blower speed (and gas flow rate)
to match boiler output to space heating and/or DHW heating
demand.
17. Swing-away control panel assembly
The Ultra control panel is mounted to a hinged subpanel, al-
lowing the panel to be swung forward and down for easy access
to the electrical connections.
18. Air intake adapter
19. Electrical entrance
Knockouts are provided in the jacket top panel, allowing con-
duit entry directly behind the control panel or near the wall.
20. Boiler drain valve
21. Line voltage receptacle
Use this connection to plug in line voltage meters or tools
while working on boiler. It can also be used for connecting a
condensate pump. Do not exceed 10-amp load.
22. P/T gauge temperature sensor well
The remote sensor for the panel-mounted pressure/temperature
gauge inserts into the outlet water pipe here.
23. Flue gas condensate drain
Connect the boiler internal condensate trap line to the heat ex-
changer here (parts supplied with boiler, but field installed).
24. Flue gas condensate drain connection
The condensate trap PVC fittings are field-installed, connected
to the condensate trap line as shown in this manual.
25. Front door
The front door is sealed to the boiler assembly around its entire
perimeter.
26. Knurled-head jacket door retainer screws
Two knurled-head screws secure the door in place.
27. Ignition electrode/flame sensor
The burner flame is ignited by applying a high voltage to the ig-
nition electrode. This causes a spark (from electrode to ground).
After ignition, the electrode measures flame signal.
28. Flame inspection window
The quartz glass window provides a view of the burner surface
and flame.
29. Flue gas dual sensor
This dual sensor monitors the flue gas exit temperature. The
control module will shut down the boiler if flue gas temperature
gets too hot. This protects the flue pipe and the heat exchanger
from overheating.
30. ON/OFF switch