IBC SL 35-199

INSTALLATION AND OPERATION INSTRUCTIONS
5-4
SL 35-199, SL 45-260 MODULATING GAS BOILERS
5.2.5 Hi-Limit Switches (water and UVHL)
Check resistance between leads. If resistance is very low, temperature should
be acceptable. If resistance is very high, temperature should be out of bounds.
A simple means of checking whether a high limit switch is open is by measuring
the AC voltage across the device. If the reading is 24 VAC the switch is open. If a
0VAC reading is shown, it is closed. NEVER connect an ohm-meter or continuity
checker across a live circuit.
5.2.6 Ignition Module
There are two approved ignition modules - Fenwal (grey) Standard and Capable
Controls (white) Alternate. Each have a red LED lamp providing the following
signals:Fenwal–1rapidashon1stenteringPre-purge,3rapidashesupon
Failure to Ignite After 3 Attempts; the Capable Controls module provides a single
ashatthestartofeachPurgeandInterpurgecycle,continuousrapidashes
during the 4 second spark interval, solid illumination following successful ignition
until burner shutdown, and a slow on/off with a 3-try failure.
Flame current can be monitored on the Fenwal. Connect an electrical test meter
-settoreadDCMicroamps(symbolμA)tothetwotestpinsatthetoprightof
the ignition module. Recycle the boiler so it enters another trial for ignition and
monitortheamecurrentreading.Whentheburnerignites,asteadyreadingof
2-7 DC Microamps should be measured by your meter. The control will lock out
if the reading drops below 0.7 Microamps. (see Section 5.3.1 - “Control Module -
Maximum ignition trials error”, and Section 5.3.2 - “Ignition problems”).
Upper Vessel High Limit (UVHL)
Water temperature high limit switch
Fenwal ignition module - DC
Microamp (μA) test points are
shown at top left corner of module
(beside red L.E.D.)