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Lochinvar Knight KB106 boiler. Lockouts from Temp Diff

Gater61 Member Posts: 9
A little less than 2 years ago we had a Lochinvar knight KB106 installed in our home to replace an old original boiler with 4 zones (installed in a large 5 ft crawl with its own loop as well). The zones are all set up and the crawl space loop kicks on anytime one of the 4 zones calls for heat.
We love boiler heat, and when working loved the lochinvar boiler. Since it was first installed, I've had the same issue. TEMP DIFF red screen pops up on the boiler and it shuts down, shutting down our heat until I go down there and click the 'reset' button. We live in Michigan, and can not even leave the State during the winter without someone going to the house to make sure the boiler isn't locked out. My installer came back 2 times to fix it, then just stopped returning my calls. I looked up Lochinvar site for a recommended contractor, I picked the one with all the 'credentials' and they came out. He said there needed to be a backflow preventer value installed, 6 inches between 2 pipes (at a "T" on the boiler, not sure the name for them) and flipped by boiler pump and my system pump putting the stronger pump of the 2 (it has 3 speed options) on the system side and the weaker pump for the boiler loop end. That Tech left and said "she's all fixed, you'll never need to get anyone out here again"... 12 hours later, same screen. Lockout. Temp Diff. Since the last contractor came out, I now get a 2nd lockout screen. OUTLET ARHL. I've attached both pictures. This system has been a nightmare and I'm just looking for any type of guidance. I can attach all kinds of pictures. I really appreciate any help that can be provided as we are running out of options it feels like.


  • Gater61
    Gater61 Member Posts: 9
    We also now get an anti-cycling code that I don't think I was getting before the 2nd contractor came out.
  • Gater61
    Gater61 Member Posts: 9

  • Gater61
    Gater61 Member Posts: 9

  • unclejohn
    unclejohn Member Posts: 1,749
    Send pictures of near boiler piping. Whats happening is the The zone vales shut and even if the system pump continues to run after burner shut down the heat has no where to go. Most likely need to pipe primary / secondary and if possible hold at least one zone open with time delay relay after tstat satisfied.
  • Leon82
    Leon82 Member Posts: 684
    edited December 2017
    The blocked message is normal and will block the boiler from starting for a set amount of time that was entered into the settings.

    The max is 10 minutes so is possible it was never noticed, or he may have turned that setting on when he worked on it
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    One of two things is going on. Either your system pump is too small, or your boiler pump is too small. It can also be a problem of too much fire capacity, over driving the system, producing heat faster than it can be distributed.

    Might try reaching out to the manufacturer and see if they have someone close to you that is certified to work on the Lochy products. Great company to work with.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • GaryJansen
    GaryJansen Member Posts: 1
    While I have no doubt you may have some issues with your system, the fault code you are seeing "outlet temp difference" is probably not related to your system.
    There are 2 sensors on the outlet side of the boiler. They are both encased in a common molex connector. If the sensors read more than a 2 degree differential, you get the fault you are seeing. A competent serviceman with the proper service manual should be able to ohm out the sensors to see if one or both are at fault. It also could be the wiring from the board to the sensors, or the main board itself. Could also be corrosion at the wiring connections causing a poor read.

    The anti cycling is not a fault. It tells you the status of the boiler. In your case, the boiler has just finished a cycle and is in a timeout mode until the next call for heat.
    Thanks Gary
    j a_2Adolfo2
  • Gater61
    Gater61 Member Posts: 9
    Thanks all! I'll get some pictures uploaded tomorrow morning. I figured the anti-cycling code wasn't anything to worry about... The Temp Diff however has really picked up as far as shutdowns/lockouts go. At least once a day now since he came over to work on it. Usually wake up and its locked out by morning. I did get another fault, took a pic of that. Will post that too. Feel good about your feedback have heard a few of these things discussed but heard some new ideas as well. Really appreciate it!
    JUGHNE Member Posts: 8,938
    Could you include the flow arrows on the pumps? It has happened that pumps have been installed backwards, not common but easy to do.
  • Gater61
    Gater61 Member Posts: 9
  • Gater61
    Gater61 Member Posts: 9

  • Gater61
    Gater61 Member Posts: 9

    The first pump in pictures is the boiler pump, second is the system pump (that pump has the 3 speed options and is set at high, I've tried all settings on this pump they all result in lockout) I'll have to take a better picture of the boiler pump to show the direction of the flow. I'm going to have to try calling the company tomorrow, the tech that was just out here I found via the Lochinvar site, they were the only certified lochinvar company in my area according to the webpage.
  • keyote
    keyote Member Posts: 659
    I had similar problems on KHN 085 and i only have one pump. It would not answer a call after another call had left the water too hot in the pipes. several things became apparent you can adjust how long the pumps run before and after ignition which can cool the water. also i had used the system sensor which prevented the single pump wired to boiler terminals runiing after zone valve closed once disconnected boiler used internal SWT sensor and ran the pump before attempting call and also after call. And as others have said their was also a settings for various temp differentials as well as how long a lockout lasts as short as 1 second.
  • Gater61
    Gater61 Member Posts: 9
    I had a Lochinver approved rep out here who replaced the sensor and have had no problem sense. He did say that I'm running the boiler in 'normal boiler' mode, as opposed to modulating. When I mentioned switching it back he said that he knows people who have had problems with modulating and their heating bills being high. I also do not thing anyone installed an outdoor sensor, so maybe that is why its not set to modulate?
  • NY_Rob
    NY_Rob Member Posts: 1,370
    If you don't have one- you should install an ODR sensor and use it. Your boiler has advanced controls designed to take advantage of the ODR sensor. Without the sensor, you've basically lobotomized your smart boiler.
  • rick in Alaska
    rick in Alaska Member Posts: 1,242
    I think you have definitely solved your problem. As ME said, there are one of two things going on. Unfortunately, there is a third option, and that is a bad sensor. I had the same issue going on with a customers KHN boiler and was told by my rep that they had some bad sensors out because of the way they were built. I changed the sensor and have had no more problems.
  • ced48
    ced48 Member Posts: 468
    Can someone explain the temperature lockout that was happening here? Are both of these sensors on the outlet side as suggested by someone here? What could cause this to happen if the sensors were operating correctly?
  • gater4456
    gater4456 Member Posts: 4
    Hi All. I'm logging on to look into fixing another problem and figured I'd let all know who read this how my KB 106 was fixed. After over 1k spent on lochinvar approved reps switching pumps, replacing pumps, re-running the 'loop' and god knows what else, I called Lochinvar and was told just to replace the 'temp diff sensor'. It was a $46 part. Since replaced, I'd never had another issue with temp diff. None of my serviceman even bothered to call lochinvar I think... as it took me one phone call. Now I'm on to another problem, which is one of my zones is stuck open, heating the room way up and always calling for heat... fun! =)
  • Zman
    Zman Member Posts: 6,975
    I am not sure what a "Lochinvar approved Rep" is.
    Are they from Lochinvar? Your regional supplier/reps office? Some guy hat took a class?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • rick in Alaska
    rick in Alaska Member Posts: 1,242
    I did mention the bad sensor......
  • rick in Alaska
    rick in Alaska Member Posts: 1,242
    Also, you probably need to replace the zone valve powerhead for the zone that is overheating. Or, it could be the actuator that it is powering.
    See if the zone valve is open by pulling on the metal lever where the wires come out. If it has no resistance all the way across, it is open. If it is, take one of the yellow wires off and see if it closes down. If it does, it is a thermostat or wiring issue that is telling it to be open, in which case you will need to trace it down. If it doesn't close, then pull the lever in to the detent position and lock it in there. Then take the cover off and take out the two screws that are on opposite corners of the plate, and pull the powerhead off. Underneath the powerhead is a pin sticking up that it turns. If you can turn it with your fingers, it is most likely fine, but there is a small chance the ball is damaged. If you don't have to change it, you will have less problems of introducing air back in to the system.
    If the pin turns freely, you most likely can just buy another powerhead and install it over the pin. Sometimes you have to wiggle it around a bit to get it to seat. Also, make sure it is locked in the open position while installing it.
    Hopefully, this will solve your issue.
  • SuperJ
    SuperJ Member Posts: 605
    Didn't read the whole thread but why does there appear to be a check valve between the closely spaced tees? Flow should potentially be allowed to go either direction across the tees.
  • Gordy
    Gordy Member Posts: 9,514
    Those tees are not close enough Together to attempt a P/S piping. Essentially the check valve was installed as a quick, and dirty fix to direct pipe.
  • hot_rod
    hot_rod Member Posts: 15,019
    check between the closely spaced tees? looks like a Bristol sticky, Solar Logic design?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream