Laars MagnaTherm HTD Series Installation And Operation Instructions Manual

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Laars MagnaTherm HTD Series Installation And Operation Instructions Manual Manual pdf 121 page image

Page 117HTDhigh voltage box. The speed of the motor is determinedby the controls logic which is delivered to the VFD by a0-10VDC signal.If it is necessary to service, remove, or replace the blower,the main power MUST be disconnected and the main gassupply to the unit must be turned off. To replace or removethe blower, turn off main power, remove hardware thatconnects the Fuel/Air mixer to the blower, then removethe hardware that connects the blower to the adapterplate. If the fan is determined to be defective, replacethe existing fan with a new one by reversing the stepslisted above. Be sure to install all the required gasketsand O-rings between blower, adapter plate, and fuel/airmixer.11.B.8 Heat Exchanger TubesBlack carbon soot build-up on the external surfacesof the heat exchanger is caused by one or more ofthe following: incomplete combustion, combustion airproblems, venting problems or heater short-cycling.Soot buildup or other debris on the heat exchanger mayrestrict the flue passages.If black carbon soot buildup on the heat exchanger issuspected, disconnect the electrical supply to the unitand turn off the gas supply by closing the manual gasvalve on the unit. Access the heat exchanger throughthe heat exchanger shrouds. Removal of the outerbaffles may be required for proper inspection. Use aflashlight. If there is a buildup of black carbon sootor other debris on the heat exchanger, clean per thefollowing:CAUTIONBlack carbon soot buildup on a dirty heatexchanger can be ignited by a random spark orflame. To prevent this from happening, dampen thesoot deposits with a wet brush or fine water spraybefore servicing the heat exchanger.1. Shut off the main power supply to the boiler.2. Turn off all manual gas valves connecting the boilerto the main gas supply line.3. Remove the blower assembly and burner from theheat exchanger.4. Disconnect the condensate drain line.5. Attach a longer hose to the drain and run it to abucket.6. Clean the heat exchanger by brushing away anylight accumulations of soot and debris. Use a nonmetallic brush with soft bristles to avoid damagingthe surfaces of the heat exchanger tubes.7. Once the tubes have been brushed clean, rinse thetubes and combustion chamber with a small amountof water to rinse all of the debris out of the bottomof the flue collector and into the longer condensatetrap line which is being diverted into a separatecontainer.WARNINGFailure to rinse the debris from the heat exchangerand temporary drain line may lead to cloggedcondensate lines, traps and neutralizers.Condensate pumps (if used) may also be damagedfrom the debris left behind, possibly causingproperty damage.8. To place the unit back in operation, install allremoved components in the reverse order. Be sureall gaskets are in place as the components areinstalled. Replace any damaged gaskets. Do notreuse damaged gaskets.9. Place the unit into operation, checking all gasconnections for leaks. Confirm all fasteners are tight.11.B.9 Gas Pressure SwitchesThe high and low pressure gas switches are 120 voltmanual reset switches that act to cut power to theinterlock circuit if the gas pressure is too low or too highfor proper operation. There is a manual reset on both.The gas pressure switches used are integrally ventlimited and do not require venting to atmosphere. Toremove a switch, remove the screw on the plastichousing and pull the clear cover off. Disconnect thethree (3) wires from the screw terminals. Twist theswitch off the pipe nipple. Reassemble in reverse order.Set the low pressure gas switch to 3” w.c.Set the high pressure gas switch to 15”w.c.”NOTE - The Warranty does not cover damagecaused by lack of required maintenance, lack of waterflow, or improper operating practices.