Laars MFTHW199 - User Manual

Questions and Answers

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esmithAug 19, 2025
What to do if Laars MFTHW199 burner does not ignite when hot water is opened?
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  Elizabeth JensenAug 19, 2025
  If the burner on your Laars Boiler doesn't ignite when you open the hot water tap, there are several things to check: * Ensure the ON/OFF button on the Control Display is turned ON. * If the Control Display is blank, verify the power cord is plugged in and the 4A fuses on the main controller are intact. * Confirm that water is being supplied to the unit, as it activates when the inlet water flow exceeds 0 gpm. * Check that the cold and hot water lines are correctly plumbed and not reversed. * Make sure both the cold water and gas supply lines are open. * Ensure the water lines are not frozen.
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vmorganAug 21, 2025
Why is the water from my Laars MFTHW199 not hot enough?
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  Jeremy JenkinsAug 21, 2025
  If the water from your Laars Boiler isn't hot enough, consider the following: * Check the temperature setting on the unit to ensure it's not set too low. * Inspect the filter in the cold water supply line for clogs from debris. * Verify that the gas supply type is correct for your unit. * Ensure the supply and manifold gas pressures align with the specified requirements. * Confirm the water flow sensor, which has three wires, is properly connected on top of the heat exchanger.
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craig78Aug 23, 2025
What to do if water is too hot in Laars MFTHW199 Boiler?
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  kellysuttonAug 23, 2025
  If the water from your Laars Boiler is too hot, take these steps: * Verify that the temperature setting on the unit is not set too high. * Check the filter in the cold water supply line to ensure it's free of debris. * Confirm that the gas supply type being used is correct for the unit.
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zwardAug 26, 2025
Why does my Laars MFTHW199 Boiler make abnormal sounds during operation?
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  Brittney WoodAug 26, 2025
  Abnormal sounds from your Laars Boiler during operation can be due to several reasons: * A leak of combustion gas between the sealed chamber and exhaust tube inside the unit. * Improper venting termination. * Insufficient gas pressure, which can cause an unstable burner flame and noise. Make sure that the venting termination complies with specifications and check the supply gas pressure is sufficient. If there is a leak of combustion gas, call a qualified service technician for evaluation.
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Thomas PhelpsAug 28, 2025
Why does the hot water temperature fluctuate in my Laars Boiler?
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  thomasdanielAug 28, 2025
  If the hot water temperature from your Laars Boiler fluctuates at the tap, consider these factors: * Ensure the filter in the cold water supply line is clean. * Verify the gas supply type is correct. * Check that the supply gas pressure is sufficient.
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Julia SmithAug 30, 2025
What to do if Laars MFTHW199 is operating but nothing is shown on the control display?
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  elijah46Aug 30, 2025
  If your Laars Boiler is operating but the Control Display shows nothing, the issue might be: * Lost communication from the control to the display. Check for loose connections and proper pin alignment/engagement on the Control's plug. You can also try cycling the power off and on using the boiler power switch to see if the display starts working again.
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Elizabeth StaffordSep 1, 2025
Why is my Laars MFTHW199 Boiler blower running at full speed with nothing on the display?
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  Leah BrownSep 1, 2025
  If the Control Display of your Laars Boiler shows nothing and the blower is running at full speed, it could indicate: * The control is not receiving power. Check the wiring for any short circuits or incorrect connections. Also, check the transformer connection to the control, referring to the wiring diagram, and ensure there is a 12V output from the transformer.
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Raymond FryeSep 4, 2025
What causes Laars MFTHW199 temperature to rise too quickly?
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  Eduardo WalkerSep 4, 2025
  A rapid temperature increase in your Laars Boiler occurs when the supply water temperature in the heat exchanger rises faster than 2°F per second during the first two minutes the burner is on. This issue usually resolves itself after a short delay, or you can manually reset it on the Control Display. Look for a message related to the TEMPERATURE SENSOR and follow the instructions for checking loose connections.
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Tanya PettySep 6, 2025
What does BLOWER FAULT mean on my Laars Boiler?
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  Jeremy DonovanSep 6, 2025
  A BLOWER FAULT on your Laars Boiler indicates that the blower is either unable to reach the required speed or does not reach 0 RPM when turned off. To resolve this, reset the system using the manual reset screen on the Control Display.
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holmeswilliamSep 8, 2025
Why is the Laars MFTHW199 blower still operating after combustion stops?
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  Jason HillSep 8, 2025
  It's normal for the blower in your Laars Boiler to continue running for about 1 minute after combustion stops. This allows it to vent (exhaust) the flue gas from the chamber.