Dunkirk Q90-200 Series II - Manual (Page 39)

39
15 - TROUBLESHOOTING
Troubleshooting Flow Chart - High Limit Control And LWCO
Burner Will Not Fire See Flow Chart, this page.
No or Insufficient
Domestic Hot Water
If installed with indirect water heater, insure end switch in relay box controlling indirect water
heater is properly connected to Cable 2. This will insure domestic water calls are prioritized. If
Cable 2 is not used, turn Economy Feature OFF.
House Will Not Get or
Stay Warm
1.
Check for air-bound radiators.
2.
Check thermostat settings including heat anticipator settings (common on non-digital
thermostats).
3.
Check Economy setting. Economy feature, like outdoor reset controls, lowers average
boiler temperature and can slow or, in some cases, prevent the house from coming up to
temperature. Move to lower setting.
Is Red LED
(LOW WATER)
On?
Is Yellow LED
(HI TEMP)
On?
Is Yellow LED
(TARGET)
On?
Is
PURGE LED
on?
Replace
Control
Control is
Sensing Low
Water
Control is
Sensing High
Temperature
Boiler
Reached
Target
Temperature
Boiler in Purge Mode
and will not fire until
temperature drops to
140°F.
See Purge page 36.
Both red and yellow LEDs are off and there is call
to fire burner, there will be 120 VAC in terminals
B1 and B2.
►120 VAC is not present, replace control.
CAUTION- ALWAYS ALLOW BOILER TO COOL BEFORE
ADDING WATER
Burner will not fire until low water condition is satisfied.
►Verify system filled with water.
►Verify sensor is inserted correctly into well.
Note: Use of heat-conductive grease may interfere with contact
between spring clip and copper well tube.
►Verify control is tightly clamped to well.
Burner will not fire until boiler water has dropped to high
limit differential set-point (10° below high limit setting).
►Verify high temperature setting is correct.
When ECONOMY function is active, control monitors
heating demand and establishes Target boiler temperatures
below high limit setting to conserve fuel. Burner will not
fire until boiler temperature drops to Target Temperature
Differential.
YES
YES
YES
YES
NO
NO
NO
NO