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Lochinvar Knight KBN106, No 24 Voltage to Low Voltage Board
fieldguide
Member Posts: 7
I have no 24v low voltage to Low Voltage Board (causing a Gas Pressure Switch Fault & Lock). I have replaced both boards, the main board twice, believing the first must have been defective. Wiring connections have been checked thoroughly numerous times. On recommendation of an online Lochinvar tech, I've also replaced the fan. I have 120v at the main board, but no 24v coming out at the output connector. I bypassed the main board and supplied 24v directly to the low voltage board. By doing this, the furnace doesn't lock out until it wants to fire and then locks out, because of course, I have shut off the natural gas since other monitoring systems are not receiving voltage. With voltage into the main board, but no low voltage coming out, are there other possibilities besides main board? Thanks for any feedback!
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Comments
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The KBN106 has a transformer dedicated to the gas valve only. It is working fine. 120 voltage is supplied directly to the main board which has its own voltage reduction and feeds the low voltage board. The fuses all check out. Thanks Ironman, other thoughts?0
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Is this wiring diagram correct?
If so, check for 24v between the terminals circled in green.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.0 -
Similar, but variations. Mine was installed in 2010. I have no voltage at any of the connection board terminals, which includes the room thermostat and therefore have no room temp display. Since there are no gas pressure switches, there is a jumper wire connecting the terminals. I'm getting the Gas Pressure SW Fault and subsequent Lock since there is no voltage here along with all other 24 v terminals.0
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Got it running!! Thanks Ironman for putting me on the right track!! I'm new to this site, so are there ways to credit you for all your help? Thanks again!!0
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So, what was the problem?Bob Boan
You can choose to do what you want, but you cannot choose the consequences.0 -
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@Ironman. I was studying my wire diagram after viewing the one you sent. I began tracing wires and realized something wasn't right. I discovered that 2 of the wire connectors were internally identical and therefore reversible. Mine were reversed! I was shocked that that was even possible! At any rate, the system is now good to go. Thanks for taking the time to help, you opened the way to solving the problem!2
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@Zman. Thanks for the help! (and friendly jibe )0
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@STEVEusaPA . Thanks for the laugh, you're hilarious!!0
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