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Noisy Boiler Options

I installed a Lochinvar Noble Combi 199. The air intact on the side of the house sounds like a leaf blower running non-stop and approaches 70dB. My 3 inch intake pipe run is approximately 10 feet. The specifications allow up to 100 feet of pipe. Is there anyway to reduce the speed of the fan in order to reduce the noise level? I've already installed the Lochinvhar pipe silencer... which reduces high frequency noise but not low frequency noise. The fan also runs non-stop even when there is no call for hot water. Is there any way to get the fan to turn off when in standby mode?


  • hot_rodhot_rod Member Posts: 13,205
    The fan should not be running non stop, only during a heat or HW call. A very short period before and after buner operation.

    The boiler can be setup to maintain temperature, or fire only at DHW call. A short delay to get HW if you chose the setting that does not maintain the boiler temperature 24/7

    Your manual will take you through the step by step procedure to check and change settings.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,945
    sounds like a defective blower, most of the mod con equipment is quiet you can't tell its running
  • DZoroDZoro Member Posts: 1,035
    Something is wrong with either the system, set up or both. What gas are you on? What were the combustion numbers both high and low fire rates? The pipe silencer will do no good if the boiler burner hasn't been tuned properly. There should be no high pitch or low pitch sounds at anytime.
  • Le JohnLe John Member Posts: 175
    I have a NKC 199 in my house. The blower is quiet on the inside of the house but I can say it does resemble the noise of a leaf blower as @SeattleBoiler mentions standing outside especially when its firing at 100%. It's a strong blower motor. Once the call for heat or hot water is satisfied the blower should continue to run for 2 minutes (Default DHW response time setting) then stop.

    Once the boiler senses the temperature approaching its set points it will modulate down and becomes very quite.

    High or low pitched sounds indicates the combustion is outside of the recommended specs or the blower motor is faulty and a combustion analysis is a must as @DZoro mentions.

    As a comparison to the Lochinvar - my neighbor has a Navien NCB and even at full fire the blower noise is much quieter then my NKC but the NKC has a bigger blower motor. He has 2 inch pipe I have 3 inch pipe.

  • SeattleBoilerSeattleBoiler Member Posts: 2
    I want to thank everyone for their feedback. I especially want to thank the Lochinvar product manager who reached out and helped me resolve the noise problem. Turned out there was an issue with the control board that kept the fan running at full speed. The strange behavior had never been seen before. With the help of Lochinvar, we swapped out the board under warranty and everything works great. The faulty board was shipped back to the factory for technical analysis.
  • Le JohnLe John Member Posts: 175
    wow that is good info to know - thanks for the update. A special shout out to Lochinvar for getting the issue resolved. Great People make a great company!
  • DZoroDZoro Member Posts: 1,035
    The combustion numbers must have been way off, especially in low fire.
    Lochinvar has a good tech support. Are your combustion numbers back to normal?
  • mikeg2015mikeg2015 Member Posts: 1,178
    edited September 2019
    One reason you need ot use at minimum a CO detector, but ideally a combustion analyzer on startup. On some of these you have to set initial gas pressure and then trim them if needed, but depends on the boiler.
  • bitcohenbitcohen Member Posts: 1
    edited September 2019
    Hi all. Maybe you will help me also? I became a first-time homeowner a few months ago, and my combi boiler has just started making a knocking / loud ticking noise whilst the boiler temperature rises from about 20 to 50 degrees, but once above 50 seems to function as normal.

    It's 2.5 years old, so just outside the 2 year warranty it came with. All very new to me so idiot's question coming up: what do I do?
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,945
    @bitcohen call the installer back or a qualified service technician who knows your particular boiler
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