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Knight Boiler Frustration

Kevin Pulver
Kevin Pulver Member Posts: 67
would have a "spare boiler in the truck"! I'll bet that looks good on bids. ("If you ever encounter any difficulties, I've got a spare boiler in the truck.")
I'm no help Paul, but I wonder if it's the zone valves. You broke your own rule of zoning by circulator and now it doesn't work. Maybe just a coincidence, but better check it out anyhow. Smile, just think of all the experience you're getting on this. And it's not 100 miles from home!


  • Paul Rohrs_7
    Paul Rohrs_7 Member Posts: 173
    This one is frustrating

    Knight nat gas boiler, 80,000 btus. New construction, radiant floor heat with domestic hot water. This zone valve system is being controlled by a Tekmar TN4 package.

    It has been operating fine for the last two months until last week when I received a call stating the boiler said "Lock Out - Ignition Failure". Kind of strange I thought. About 2 weeks ago, the plumber and inspector complete the air-test on the gas line. After that, my trouble started. Plumber swears my boiler and gas piping were isolated during test. I have changed the gas valve on this boiler to ensure it has not been over pressurized.

    Thankfully, the HO's have not moved in yet and no one is out of DHW or heat.

    By the numbers I have verified everything on the Service Manual troubleshooting guide.

    Gas pressure at 10.5" WC

    Vents clear

    Combustion chamber clear, no fiber mesh grounding out spark ignition. Igniter and rectification probe clean. (This boiler was set up with a combustion analyzer to factory specs.)

    24V from control board to gas valve.

    I am NOT getting any microamp reading from my rectification probe as it tries to fire. Rectification probe has been changed and the cable does have continuity and a solid connection.

    4 very good service techs at Lochinvar have been helpful, but yet unsuccessful. I have now spent a total of 11 hours on this troubleshoot and don't feel I am any farther than I was in the 1st hour. According to the service manual, the ONLY thing left to do is change out the control board.

    This system ran beautifully for 2 months and then this. It is waking me up at night looking for answers.

    Anyone else have any issues with the Knight?

    I handled all of the low-voltage wiring, but the electrician on-site did the wiring for the pumps. I had the blue box laminated and the TN4 pre-mounted and prewired so that the bulk of the wiring was hidden. I wasn't really pleased with his attention to detail. Enough said.

    As it pertains to the attached picture, my camera battery died and I have not re-programmed the date after installing the new battery.


  • ScottMP
    ScottMP Member Posts: 5,884

    I was thinking contruction dust but I think you've covered that Only other thing i've got is grounding or voltage drop from new construction ?

    I would think I board would be covered but it might not answer your questions


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  • Weezbo
    Weezbo Member Posts: 6,232
    That is picture perfect.

    When Scott came up from Lochinvar this winter, i asked him if there were any issues regarding grounding that he might have encountered..."no. we haven't had any issues"..

    this is the second time in as many years that i have asked ....thing is the classes while in two different years are within a four month spread... i would tend to believe it may be something unrelated to the Knight. *~/:)

    One go round just to make certain i asked Sid if there were any problems or recommendations he might have on Bonding...Sid is swift..i got the sence that he is us as it were.

    while i am not great at troubleshooting natural gas, i have seen a gas valve that had been hammered with too much air pressure on a "Test" the test as far as i can see might dislodge some thing past a drip leg after the T yet before the valve ,... once the valve is connected maybe that oil or debris is the source of lockout... you said it shows as an ignition problem ...hmmmm.... is there some chance something was disconnected from an electrical connection at that time?

    i have the same type of help at times...people dink with something when i am away from it and suddenly low and behold i am fixing something that was not broken...

    listen , this is not going to self repair so..i am offering something that i found that may help in perspective

    Lessons4living.com the Labyrinth

    look Deep within the Labyrinth sterogram *~/:)
  • S Ebels
    S Ebels Member Posts: 2,322
    Sounds like

    You've covered all the bases except the board Paul. That'd be my next step. If I understand the way flame rectification works, the board sends a signal out which is passed through the plasma surrounding the flame to the flame rec probe. The fact that you are not getting any signal at all probably means there is no signal in the first place. If you had a weak flame signal, I'd think there was a problem with the flame, probe, corrosion or grounding but that doesn't seem to be the case. Stick a new board on it and I'll bet it works. I get side tracked on occasion also by coincidental events that are wholly unrelated to the failure, like your gas pressure test. They just make you go hhmmmmmmmmm....... and make you a little smarter for next time.
  • Dan Foley
    Dan Foley Member Posts: 1,258


    Try changing the cable. I had a boiler that gave me nuisance lock outs as you described. I had checked the continuity and resistance of the cable and it checked out. Nonetheless, as soon as I changed the cable, the problem disappeared. - DF

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  • hot_rod
    hot_rod Member Posts: 21,853
    Remove and reinstall

    every single wire connection. I had one do the same thing last fall. Changed the probe, wire, etc. I had a spare boiler in the truck and I even changed out the module. Still the error code. After I removed and tightened every wire I could find the problem went away.

    I also had one with a white styrofoam coffee cup in the air intake on the roof. It did the fail to ignite problem also. Be sure the intake air vent is clear.

    Good ground everywhere? Take a wire with alligator clips and ground to a copper pipe somewhere.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Paul Rohrs_7
    Paul Rohrs_7 Member Posts: 173
    Boiler is only item not operating

    All zone valves, circs, DHW respond to the TN4 and the boiler is receiving the call for heat just like the DR ordered.

    Dan- I did also replace the cable.

    I will disconnect and reconnect all electrical connections and double check for proper grounding.

    I think I'll request a board for replacement if everything else checks out.

    Thanks for the help.


  • We had a case of an Ultra80 on a very small, superinsulated system (total overkill, and the client knew it) where, when firing under lower heat demands it fires so cooly and for such a short period of time, that at the end of the firing, the colder gas left in the burn chamber nozzle thingy (yeah, I'm not a boiler guy, sorry) was actually enough to cause the nozzle to condense.

    condensate would collect under the nozzle, where the flame probe was.

    Next time it tries to fire.. no flame under the nozzle, no proof, trips out. Trips out X number of times, and goes into hard lockout.

    we had the initial fire fan speed adjusted to fire a little bit harder on ignition and that settled the issue. You might be able to tweak the tN4 parameters to be a little more aggressive on ignition, or the knight's parameters themselves...?

    Or this might not be related at all, but it was a troubleshooting nightmare on our end and our installer's end too... he just happened to be on site when it occurred once, and he got to see the problem first hand. But after it locks out for awhile, the condensate evaporates... no evidence....
  • Dick Charland
    Dick Charland Member Posts: 178

    Where are you running gas pressure wise? I see you stated 10.5", instructions want to see 4-8" operating. Not sure if gas regulator not locking up, disturbed from test?
  • Dave Stroman
    Dave Stroman Member Posts: 763

    I was going to say the same thing about the gas pressure. That is high. I have seen gas regs spike and allow way to much gas pressure.

    Dave in Denver
    Dave Stroman
  • Dave_4
    Dave_4 Member Posts: 1,405
    i got 13 knights installed...so here goes...

    First of all, all of them are in a multiple boiler setup – I wouldn’t dare install a single modcon boiler of any manufacture including vie$$mann!!!, when manufactures put in a complete dual combustion system from the inducer fan, through gas-valve, down to the flame rod, only then will I reconsider!!! I only get two hours sleep a night and I really really need those two hours!!!

    Having said that : I have discovered a few interesting things about the knights:
    They come with leveling feet – and I use them to tilt it towards the back a little to keep the condensation off the flame rod – half of the time I had lock-outs, they came out wet

    The factory wiring on them is dismal – I have called them on it – it’s like talking to a wall: did you know that the high voltage terminal screw block has a row of spade lug terminals under it that get lose, pulled, or whatever, and will give you grief.

    The biggest single sin, is the low voltage terminal block, especially since a few more inches of wire would have allowed it to be oriented sideway,s instead of toward the back where it almost impossible to get at correctly, and to see if the wires are in right, had one, with a loose wire on the cascade, and it gave me a blank display, and would not fire, all I did was reconnect the inter-boiler wire and it came right back to life

    Maybe if someone a Lockinvar reads this thread, they will do something about the wiring!!!

    Also you’d think that a boiler, that lives, in a likely to be wet environment would be able to handle water, or at least protect the parts than cant, well, fo-ged-abow-eet, if water gets on top of the back of the boiler, it will seep into the board area, and drive you crazy, mine are all covered with plastic, after having a few perfectly working boilers go nuts, I looked at your pretty picture, and you could have easily purged water on top of that boiler, now you will need to take it apart and take a blow drier to it, you just loosen the 5/16 nut on the right and take the one on the left off completely and lift and slide left , hope you left enough slack on the low voltage wiring – one drop of water on the lower board and your boiler is having PMS – and if the drop is in the wrong place it could be permanently dead – so I concur, that a board replacement is in order for you

    Another caveat is their pump recommendations, which contradict their own head and flow graphs, eg if you install a KBN-500 – don’t even think about putting in a 0012 like they recommend, you will need a PL-55 – and mine were going into a 4” header and into a 4” Calleffi Hydro-Isolator so I had no resistance to speak of in my primary loop – I ate 4 pumps, so step up the flow and head, unless you are only using the boiler for a low temp load – then you can stay with their recommendations

    After all this, I am still married to the knights as they come with a Multiple Boiler System built in (“CASCADE”) and I only do MBS, I don’t have to worry about water ph like the ultra’s, I can control them from a Building Automation System, without buying an AM4 module – and can drive the flue 100ft – they are real nice – but you need a good rep, Wallace-Ennace out here on Dan’s “isle of long”, has great support for this boiler, but, you need to understand them – eg if you do a high temp loads like DHW, you need to set the “offset” right or you will get auto-reset high limit lockouts – (on the 500 it doesn’t auto reset) – eg: for a 180 load you set the setpoint a 172, the offset at 8 and the differential at 12, so the boiler would fire at 100% to 172 and throttle back until it hits the offset (172+8=180) – and go off until it comes down to 168, you can play with these numbers,

    Overshoots are a problem with all low mass boilers, if you set them to for 180, and the return is above 175, and your load suddenly gets light, the boiler will overshoot to 200 in a flash!! – this is especially bad with external boiler controls, as the sensor is outside the boiler on a combined header and too late to respond – with the knight “offset” this doesn’t happen, as the temp climb in the offset range, is throttled way back – it’s my favorite feature of the boiler – of course on external controls, I limit my setpoint to 170 – In fact, as I now use low mass boilers exclusively – from LAARS PENNANTS to these KNIGHTS, I design my hi temp loads for a max water temp of 170 – I had a pair of 2 million btu pennants on a tekmar 268, overshoot whenever my heat load went away but the DHW load stayed, by the time the tekmar throttle back, both boilers had hit their hi limits, and the sudden rise in gas pressure, (remember 4 million total) would trip my high gas pressure switches, as we have hi pressure gas and by the time the regulator adjusted it was too late – that was a job with Innovex Technologies’s IWorX BAS, that siggi wrote an article about, and I was able to use their alarm module with a sensor to override the system and injection pump back to ON, for a purge override
  • Dave_4
    Dave_4 Member Posts: 1,405

    Hey Paul,

    Every job I see that you do you have the strapping holding the expansion tank with some sort of rubber banding. Would you be so kind as to tell me what it is and where to get it? BTW, I really like the way it is located away from the piping and supported on its own. I always pipe it so it is supported by the Air Eliminator and worry about how secure it is.

    Thanks in advance,

    Rob Blair
  • Paul Rohrs_7
    Paul Rohrs_7 Member Posts: 173

    Is the company name. Here is the link to their website.


    I use "Spiral Duct Clamps" for most all of my expansion tanks.


  • Hvacman
    Hvacman Member Posts: 159
    Reverse polarity

    in the supply wiring will cause random flame rectification issues... Maybe your dislike of the electrician is warranted! :-)

  • Paul - Sorry to hear that your having a problem with a Knight. Looking at what you've done, I'd say you covered all bases - overpressurized Gas valve - Checking all connections for bad connector, etc.

    I'd change the board without waiting any longer. It won't give you an answer but it will most likely solve the problem.
  • Kal Row
    Kal Row Member Posts: 1,520
    yeah i forgot , those spade terminals...

    under the hi-voltage wiring block were reversed on one of them - so it might not be the electrician - lots of really stupid but invisible wirng issues will take this boiler out!!! a real shame for an otherwise great boiler
  • Ubiquitous
    Ubiquitous Member Posts: 14
    Bad Board?

    I have read through the reponces you have recieved, as well as your inital issue. I would agree at this point the two issues (Purging and No Flame IGN) are possibly coinsidental, but maybe something happened during the process where the board was hit with water. I would atleast recommend a visual inspection of the board to check for signs of water incurtion. This type of damage is easily spotted by a scorch mark at the lower right side of the transformer. If you have other questions we are always happy to assist you. Please feel free to contact us here at 1-800-722-2101.
    Ernie Chase
    Lochinvar Technical Support
  • Paul Rohrs_4
    Paul Rohrs_4 Member Posts: 466

    This unit is back on-line.

    I went back this morning and set up camp.

    1. I disconnected/reconnected ALL electrical components.

    2. Bumped minimum rate of Tekmar control to 30% (up from 20%)

    3. Placed alligator clip from combustion chamber post to ground.

    4. Disconnected NH coupler from intake/venturi, bypassing PVC inlet piping.

    (Edit:) 5. Adjusted gas pressure to 9" WC.

    ......Fired right up!

    In reverse order I reconnected intake, removed alligator clip, reduced minimum firing rate back to 20%. Fired right up again. The only variable remaining was the disconnection and reconnection of wiring harness' and spade connectors. (Edit: and Gas pressure) Go figure.

    While relieved that this boiler has experienced a re-birth, I find it a bit troubling that I cannot pinpoint the cause of the failure. Is this going to happen again down the road?

    After running for 2 months with flawless performance, trouble starts because?...... I could understand it on initial startup, but did someone body-slam the boiler and knock a connection loose? Am I not living "Right"?

    Anyway, thanks all for the assist and advice. Special thanks to Chuck Shaw from HTP. This is one of the classiest gentlemen I know.

    I did double check the control board. No evidence of any moisture.


  • jackchips_2
    jackchips_2 Member Posts: 1,338
    What an

    excellent follow-up, Paul.


  • Kevin O. Pulver
    Kevin O. Pulver Member Posts: 380
    Paul, you are nothing

    ... if not thorough. And you live better than most folks I know. I wish I had more to tell you, but glad to hear it's operating. And on the bright side, if it ever does it again, Hot Rod can send you a board! ;-)
  • Jeff Lawrence_25
    Jeff Lawrence_25 Member Posts: 746

    You mean like these?

    Can you say oops? Water on the board caused it.
  • Kal Row
    Kal Row Member Posts: 1,520

    it might well have been the spade connectors cause it was so for two of mine - one was loose and one was reversed - i like so much about these boilers - it's a crying shame about the wiring - you tell the customer that this boiler is the best thing since sliced bread and then next thing - it's out on something stupid - hello Lochinvar - are you listening??? :<> - maybe i should do a few munchkins – the htp rep (a sweet guy called Jake greenwood from venco sales) saw my jobs and begged us to go big with them and we declined perhaps I was too hasty…
  • Kal Row
    Kal Row Member Posts: 1,520

    besides a plastic over the top, i also put duct tape alongside the board where the cover meats the boiler and where the low voltage wire goes in the back
  • Kal Row
    Kal Row Member Posts: 1,520
    ps:If you get Ernie Chase on the phone he will be very helpfull

  • hot_rod
    hot_rod Member Posts: 21,853
    loose connections have been an issue on ALL brands

    by the way.

    Many a Munchkin get perfectly good parts replaces due to loose wires and frustrated service techs. I've been one:)

    Ask the any factory how many perfectly good modules get returned :)

    Granted it should not be required (checking wire connections) but it is a VERY simple first step when troubleshooting intermitant faults. Just costs about 1/2 hour of your time.

    I had one where the crimp on spade terminal fell off in my hand. It probably powered fine on the factory test bed, but the trucking ride gave it a real test!

    One nice feature of the Knight is it will run with just the ignitor as a flame prove, should the prove rod be an issue.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Paul Rohrs_7
    Paul Rohrs_7 Member Posts: 173

    My perspective is still that the Knight is still a VERY good boiler. Like most, I have idea's that I think could improve on the boiler I install.

    I wish I wish that all engineers from EVERY manufacturer had to do parts change-outs on every boiler they produce. The hydronic community would be better for it. Ever change a gas valve on a Knight? An 8"x8" access plate on the back of the boiler would be great. It's not like the cabinet is pressurized or anything, and getting your hand, light, mirror, and allen wrench in that small area makes me believe I could be an Olympic Caliber Contortionist. Also, the same size HEX screw would be helpful. The four small allen screws securing the gas shut off and nipple to the gas valve were NOT made to be replaced. EACH one stripped out the micro-second the correctly sized allen wrench found its home.
    Channel locks to the rescue. It is a pet peeve of mine when allen screws strip out and Molex plugs flop around.

    Are there different grades of Molex connections? Good,better, best? Spend the few extra bucks on the best molex connection, I'll pay.

    My tone of voice (typing) should only be noted as constructive, not bitter.

    The fact is that I have installed quite a few Knights and this is the first one with any sort of glitch.


  • Kal Row
    Kal Row Member Posts: 1,520
    are you sure about this secondary sense feature...

    cause i had one that fired up - but as soon as it got pass 35%, it quit, and all i did was pull the sense rod, wiped it off with my hand - and all was ok - that leads me to believe that if they are using the spark electrode for sensing also, that it's only to for the initial firing time, if you saw it in their docs please point me at it – tnx

    hey: my reps engineer swore that the 500 also auto resets on hi-limit, but, you have to do a manual reset from the keypad – the 500 also only has one trial for ignition as opposed to the others which have 3 – but when I am feeding two turbomax 109’s with 14 showers, and space heating , and spa heating, and snowmelt – i need 4 500's and they will all be going full tilt

    so far in only use 5 knights residentially the other 8 were commercial - 4-500's and 4-399's
  • Kal Row
    Kal Row Member Posts: 1,520
    you are too nice...

    i am less forgiving – as i had 5 glitches out of 13, and somewhere in the $6500 i spent on the 399's and the $9300 i spent on the 500's, there has to be a few extra bucks for decent connectors and a splash guard for the electronics, and to turn the low voltage board sideways, i didn’t flame them until now because my rep has been very responsive - but Lochinvar has to own up, i am looking at a job now, that could take Laars REHOS or Lochinvar Power-Fins - they are spec equivalent - which would you choose?
  • Jeff Lawrence_25
    Jeff Lawrence_25 Member Posts: 746
    Some things are amazing

    I ordered the Knight and told the sales guy that that I needed it in a week. "No problem," he said.

    The day before the install, no boiler. It was starting to get cold out. I called the sales guy and asked. The Knight was at the freight terminal and was to be delivered the next day, the (supposed) install date. After I raised a bit of grief, sales guy drove his car to the terminal to pick it up and we met up.

    Long story, sales guy had to lay the boiler on it's side to fit it in the back seat. We figure that some water splashed onto the board when he laid it down or we picked it up.

    The response from Lochinvar was beyond exceptional and I now have a very happy customer with much lower gas bills.

    As I recall, Ernie was one of the gents that came down and did the site visit to check the problem personally.

    Here's a pic of the old one. As Chris (JCA) said, the BTU's were waving at the cast iron as they passed by.
  • hot_rod
    hot_rod Member Posts: 21,853
    getting that much HP

    in such a small case does tend to reduce service-ability. I'd like to see Lochinvar dull the edges of the steel cases. Razor sharp should you slip.

    I do all the LP conversions and wire checks on my work bench now. It allows you to work from all sides and even lie the boiler on its back to assure that cork burner gasket stays in place :)

    All things considered mod cons bring more pluses then minuses to the job.

    The controller alone is worth the price of admission on the Knights. I suspect few installers really dig into the true potential of that control.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Kal Row
    Kal Row Member Posts: 1,520
    you nailed it...

    a control board - that does setpoint, reset, setback, mbs and bas input, right out of the box is hard to beat - it's why i am still using them
  • JJ_4
    JJ_4 Member Posts: 146
    Design Issues

    Paul and others, an idea for the design issues you mention...

    They (the manufacturers) should employ the use of user groups during their design process. A step further would utilize a human factors/ergonomic engineer(s) to lead such a group. End users (you guys) would be in on the design, physical and functional, from start to finish...evaluating prototypes along the way. The money they would spend on this up front would save costs (for everyone) in the long run.
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    I view this as a design flaw

    On the Knight, Munchkin and several others which are "sealed combustion" design, the electronics are located in the same compartment as the burner. The boards are subjected to anything that passes into said compartment along with the combustion air which may be -20* or 90* and contain who knows what for humidity. IMHO the engineers that design these things should have taken this into account when laying out the pieces and parts of the boiler.

    Notice where Viessmann chose to locate the electronic control on the Vitodens and ask how many connection issues there have been with them. I've not had a single one and I suppose this is due to the intake/burner area being completely isolated from the electronics.

    I'm not thumbing my nose at anyone or any manufacturer nor am I claiming superior German engineering but hey, it is what it is and the facts speak for themselves
  • hot_rod
    hot_rod Member Posts: 21,853
    Actually the Knight

    has the intake air pipe Fernco-ed directly on to the blower. It doesn't use the case as the combustion air chamber. Better yet, should there be a gas leak in the gas train both exhaust and intake are direct outside.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    I could swear......

    It just dumped into the burner compartment on one we installed during the winter. But being that I'm over 50 now :( I find that I'm confused even more than normal. I'm going to check that out. Thanks HR

    That being said, I'll still maintain that the burner compartment is no place for electronics.
  • Kal Row
    Kal Row Member Posts: 1,520
    i'ts not really a problem..

    cause i am using it on hi temp loads - the boiler room is hotter than the boiler cabinet - (my pipe insulator is playing catch-up) –

    it’s the perfect boiler as long as they do three things:

    1)put an 8”x8” plastic right angle guard coned inwards right under the back right, so that any water seeping in from the side or back is deflected away from the electronics

    2)turn the low voltage terminal board 90 degrees to the left

    3)put one of those plastic twist to open and twist to close wire holders where the wire bundle leaves the spade lug bank under the HV terminal board so that they doesn’t get loose in shipping or accidental tugging by an installer

    they already updated their pumps – see the new i&o manual on their site – so the flow with high temp load problem is now solved

    I happen to be currently proposing about 14 knights to heat air handler coils in a commercial building – again high temp loads – this one is going to be tough sell cause the local gas co, keyspan, is offering them FREE, a 4 module 5.2 million monster peerless A211-26 cast iron boiler – hey, they give out what ever draws the most gas…. And it will take years to make up the gas savings cost – on the other hand, I am not only proposing the knights – but also Variable Frequency Drives on the air handlers, so the total modulated picture is huge – nevertheless – it’s hard to sell against FREE – the epa should be on keyspan’s back for this kind of behavior

    On my wish list for the knight’s is an extended blower option – have a house that’s 64’s ft tall and 90ft long and has very little room on either side, so I have to vent up, going 40 ft almost horizontally toward back of house from boiler room, then I turn up – but can only go half way up before I run out of the 100ft limit – it’s 5ft per 90el and 3ft per 45el

    Ps for those of you running long pvc vent outside, use some sliding material inside the kindoff clamps – or else the pcv will pop constantly from expansion and contraction noises
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