Limit Control Troubleshooting - Dunkirk DXL-125 Installation, Operation And Maintenance Manual

Fahrenheit/Celsius Change
Control has the ability to operate in degrees Fahrenheit
(default setting) or Celsius.
To change from Fahrenheit to Celsius:
1.
Set low limit to 112°F
2.
Set high limit to 112°F
3.
Display will delay 2 seconds and then display an "F".
4.
Push the LWCO Test Button to change setting to "C".
5.
Reset the limit dials to the correct settings.
When control is in Celsius mode, a "c" appears in
temperature display as third digit whenever temperature is
below 100°C.
Table 6 - LIMIT CONTROL TROUBLESHOOTING
Temperature Display Exceeds
High Limit Setting
No Domestic Hot Water from
Tankless Coil
Boiler will Not Maintain Low
Limit Temperature
Temperature Display Differs
from Boiler Temperature
Pressure Gauge Temperature
Reading
TSTAT Light (Green LED) is
Not On
Low Water Light (RED LED)
is On
TABLE 7 - SYSTEM TROUBLESHOOTING
No Or Insufficient Domestic
Hot Water
House Will Not Get Or Stay
Warm

LIMIT CONTROL TROUBLESHOOTING

Under normal operation, boiler temperature continues to rise after control shuts off the
burner. This condition, known as "thermal stacking", results from hot boiler surfaces
continuing to release heat into the boiler.
Make sure low limit setting on Control is properly set.
If low limit setting is dialed fully counter clockwise, it shuts off the low temperature
maintenance feature.
Check for overlapping high temperature setting. If high limit setting is below low limit
setting, control will default to high limit setting.
Temperature variances can result from differing water temperatures within the boiler or
different reaction times of the two devices. If the control temperature is significantly below
the temperature pressure gauge temperature, make sure the thermistor is inserted all the
way to the end of the well. DO NOT USE ANY HEAT TRANSFER PASTE OR GREASE.
The TSTAT light indicates when there is a call for heat. If a call is known to be present and
this light is on, check the wiring to the T-T terminals.
READ WARNING ABOVE. Low water condition is a serious and potentially dangerous
condition. Do not attempt to add water to a hot boiler. Allow boiler to fully cool before
adding water.
1.
If heating system is filled with water, pull sensor out of well and inspect it. Verify the
metal clip on the sensor is intact. This metal clip must be in contact with the inside of
the copper well in order for control to sense presence of water. Check well does not
have excessive build-up of heat transfer grease that may interfere with clip contacting
well.
2.
Remove well and examine for excessive residue build-up. Clean and re-install.
If installed with indirect water heater, insure end switch in relay box
controlling indirect water heater is properly connected to cable 2 (see
wiring diagram). This insures domestic water calls are prioritized. If cable
2 is not used, turn Economy Feature OFF.
1.
Check for air bond radiators.
2.
Check thermostat settings including het anticipator settings (common
on non-digital thermostats).
3.
Check Economy settings. Economy feature, much like outdoor reset
controls, lowers average boiler temperature, can slow or prevent
house from coming up to temperature. Move to lower setting.
!
WARNING
Burn and scald hazard. Do not add water until boiler
has fully cooled. Failure to follow these instructions
could result in death or serious injury.
To change from Celsius to Fahrenheit:
1.
Set low limit to 44°C.
2.
Set high limit to 44°C.
3.
Display will delay 2 seconds and then display a "c".
4.
Push the LWCO test button to change settings to "F".
5.
Re-set limit dials to correct settings.
24 240009041
P/N , Rev. C [04/30/2017]