Laars NEOTHERM NTH Installation And Operation Instructions Manual

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Laars NEOTHERM NTH Installation And Operation Instructions Manual Manual pdf 34 page image

LAARS Heating SystemsPage 34the burner door blower arm. If the fan is determined tobe defective replace the existing fan with a new onereversing the steps above. Make sure to install all of therequired O-rings and gaskets between the blower armand the blower and blower face and venturi flange.7.2.8 Heat Exchanger CoilsBlack carbon soot buildup on the external surfacesof the heat exchanger is caused by one or more of thefollowing; incomplete combustion, combustion airproblems, venting problems and heater short cycling.Soot buildup or other debris on the heat exchanger mayrestrict the flue passages.If black carbon soot buildup on the heat exchangeris suspected, disconnect electrical supply to the unit,and turn off the gas supply by closing the manual gasvalve on the unit. Access the heat exchanger through theburner door at the front of the boiler, and inspect thetubing using a flashlight. If there is a buildup of blackcarbon soot or other debris on the heat exchanger, cleanper the following:CautionBlack carbon soot buildup on a dirty heat exchangercan be ignited by a random spark or flame. Toprevent this from happening, dampen the sootdeposits with a wet brush or fine water spray beforeservicing the heat exchanger.1. Shut off the 120 Volt power supply to the boiler2. Turn off all manual gas valves connecting theboiler to the main gas supply line.3. For NT 600 models only (all other sizes pleaseskip to step four). NT 600 models will require thegas valve to be removed in order to remove theburner door. To do this, remove the wireconnections from the gas valve. Remove the flangebolts from the gas supply pipe connected to the gasvalve (1B). Remove the flange bolts connectingthe gas train to the venturi (1A). Remove the gastrain assembly keeping gaskets and o-rings.4. Remove the four bolts connecting the blowerflange to the burner door arm.5. Remove the nuts located on the outside diameterof the burner door to the heat exchanger.6. Remove the burner door/burner assembly from theheat exchanger.7. Disconnect the condensate drain line.8. Attach a longer hose to drain and run to a bucket.9. Clean the heat exchanger by brushing lightaccumulations of soot and debris. Use a brush withsoft bristle (non metal) to avoid damaging thesurface of the heat exchanger tubes.10. Once the tubes have been brushed clean rinse thetubes and combustion chamber with a smallamount of water to rinse all of the debris out of thebottom of the flue collector and into the longercondensate trap line, which is being diverted into aseparate container.NOTE: The Warranty does not cover damage causedby lack of required maintenance, lack of water flow,or improper operating practices.WARNINGFailure to rinse the debris from the heat exchangerand temporary drain line may lead to cloggedcondensate lines, traps and neutralizers. Condensatepumps (if used) may also be damaged from thedebris left behind, possibly causing property damage.11. Install all components removed in the reverseorder to place the appliance back in operation.Make sure all gaskets are in place as componentsare installed. Replace any damaged gaskets. DoNOT reuse damaged gaskets.12. Place the appliance in operation according toSection 6.2 checking all gas connections for leaks.Confirm all fasteners are tight.7.2.9 Gas Pressure Switches (optional)The high and low gas pressure switches are 24Vmanual reset switches that act to cut power to the gasvalves if the gas pressure is too low or too high forproper operation. The gas pressure switches used areintegrally vent limited, and do not require venting toatmosphere. To remove a switch, remove the screw onthe plastic housing and pull the clear cover off.Disconnect the two wires from the screw terminals.Twist the switch off the pipe nipple. Reassemble inreverse order. For natural gas, set the low gas pressureswitch to 3" w.c. For propane, set the low gas pressureswitch to 5" w.c. For natural and propane, set the highgas pressure switch to 14".SECTION 8.Trouble Shooting8.1 Sequence of OperationNeoTherm is a cold start appliance that shouldstart only on a call for heat from a tank aquastat, roomthermostat, zone valve end switch or other spacetemperature control device.1. Upon a call for heat: (a) the internal pump andsystem pump will start; (b) the blower will begin a30 second pre-purge.2. Following the prepurge cycle the direct sparkignition will spark and will begin a 4 second trialfor ignition. The unit is allowed one or threeignition retries.3. The gas valve will then be energized and a reducedrate ignition will occur. The unit will remain in areduced rate start-up period for several seconds.4. After the reduced rate start time is over, the unitwill be in normal operation. Firing rate willmodulate based on the heating load via the