Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Lochinvar Knight XL Ignition Failure

Heatandbeat77
Heatandbeat77 Member Posts: 2
in Gas Heating

Hi all first time using website looking for some insight on some troubleshooting on some Lochinvar boilers. I am a apprentice pipefitter from MA.

This might be a little long winded but if anyone is interested I am currently scratching my head here before buying parts.

Originally noticed Ignition failure , troubleshot and found bad gas valve , verified 24v present from the board to the gas valve, No gas pressure change at my manometer.

Returned and replaced with new gas valve. ( Also have new flame rod, Ignition spark electrode )

Fired unit off and checked my gas pressure ( 9 in WC - manual calls for in between 4 - 14 WC )

Same alarm, IGN failure, reset shut boiler room lights off and verified I heard and saw a spark, no ignition , I do know my combustion air is running.

According to manual under troubleshooting this alarm, after verifying all that I've went through it calls to change the Integrated control board, at this sight I have 3 Lochinvar boilers so I was able to test the control board on another boiler, fired that boiler up with failed boiler's board, Flame ignition failure = So I do know that I have at least a bad board.

My confusion comes next. I took the second boiler's board and switch it over to the first boiler ( which I don't like to do but was very curious now) (( Failed boiler , Good Board )).

Reset boiler, and still came in with flame failed ignition. At this point I pulled off heat exchanger arm and inspected inside and burner. To my eye it is clean and I can see light through it. I originally cleaned this section prior to all of this troubleshooting too.

Planning on calling Tech support but was wondering if anyone has any point of view or If I could be missing anything at all

Thanks a lot looking forward to any response

Comments

  • pedmec
    pedmec Member Posts: 1,192
    edited March 25

    You need to set up the gas valve. Zero governor gas valves are not plug and play. You need to turn the throttle adjustment screw closed and then open it by turning the throttle adjustment screw 6 full turns. this should get you ignition and then set you can perform your adjustments from there with a combustion analyzer. this is just the starting point.

    Heatandbeat77
  • Heatandbeat77
    Heatandbeat77 Member Posts: 2

    This is a Honeywell gas valve from factory for my model number of KBN701 , that is set at factory , I verified gas pressure coming out of my valve at 9 in WC. This isnt a zero governor. "

    "The gas pressure must remain between 4 inches w.c. (.99kPa) minimum and 14 inches w.c." = manual

  • pedmec
    pedmec Member Posts: 1,192
    edited March 26

    You have the large knight. I didn't realize the size.

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,389
    edited March 25

    Does the gas pressure change when the boiler tries to fire? It should drop less than 1” or so.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • GGross
    GGross Member Posts: 1,484
    edited March 26

    Hopefully the pressure coming OUT of the valve isn't 9". If its a factory set gas valve then the boilers will have lochinvars "hellcat" o2 trim. if it isn't a hellcat model there is certainly something that needs setting up. to properly check gas pressure you need 4 values, this is for any combustion issue. and to be clear when you are checking the pressure on these boilers at the valve you are checking the INCOMING gas pressure, not outgoing

    1- static pressure, this is pressure when the unit is off

    2- value at ignition, what does the pressure drop to at ignition (lowest number)

    3- value at high fire, run equipment to max fire rate, stabilize for a minute, record the lowest value while at high fire

    4- lockup pressure, shut down the burner after steps 1-3 and record the pressure after shutdown.

    if there is a 1" wc deviation from static then your gas supply is insufficient, if the lockup goes above or below the range that indicates a regulator issue. could be other issues as well, but gas supply needs fixing first. Lochinvar started specing out regulators on commercial systems for this exact issue.

  • GGross
    GGross Member Posts: 1,484
    edited March 26

    according to their install manual you do need to set up the gas valve. you may confused because the gas pressure section states not to adjust the outlet pressure, which is correct. you still need to set up the gas valve and make adjustments to it.

    https://www.lochinvar.com/lit/100329949_2000586636_Rev_X_(KBX_I%26O_64517).pdf

    kbn.JPG

    kbn2.JPG
    Alan (California Radiant) Forbes

Categories