TubeGuru
Unretired defense industry engineer
Our home has a Lochinvar Knight KBN105 residential boiler that was installed three and a half years ago. It has been cleaned every 12 months when the service-due notice appears on the screen. It runs on propane from a 1000-gallon underground tank.
A couple of months ago when the temps started going below freezing, we’d wake up to a cold house and warm water. Turned out the boiler was locked out due to “Fan Speed Low”. This would happen every morning and sometimes twice more during the day. When the cold spell ended, it would still lock out every couple of days.
Our service tech consulted the manual and called Lochinvar, and their suggestion was what we expected: replace the blower and/or the integrated control board. We opted to try replacing the blower ($500). The next morning there was a new lockout for “Fan Speed High”, and after a reset it was okay for a week. Now it seems to be doing the Fan Speed High lockout one or two times a week. Spring weather is coming so it is not below 35 these days. The intake and exhaust vents do not appear to be blocked, and the outside air temp sensor appears to be working correctly.
Does anyone have experience with this kind of problem? What could be the cause? Does it point towards replacing the $800 control board? How about a loose ignition wire - it does not snap on with a satisfying click like an automotive spark plug wire.
Edit: I just found out that "Fan Speed High Lockout" really means the boiler cannot ignite after four (4) tries. After multiple resets, it won't ignite at all.
Walt
A couple of months ago when the temps started going below freezing, we’d wake up to a cold house and warm water. Turned out the boiler was locked out due to “Fan Speed Low”. This would happen every morning and sometimes twice more during the day. When the cold spell ended, it would still lock out every couple of days.
Our service tech consulted the manual and called Lochinvar, and their suggestion was what we expected: replace the blower and/or the integrated control board. We opted to try replacing the blower ($500). The next morning there was a new lockout for “Fan Speed High”, and after a reset it was okay for a week. Now it seems to be doing the Fan Speed High lockout one or two times a week. Spring weather is coming so it is not below 35 these days. The intake and exhaust vents do not appear to be blocked, and the outside air temp sensor appears to be working correctly.
Does anyone have experience with this kind of problem? What could be the cause? Does it point towards replacing the $800 control board? How about a loose ignition wire - it does not snap on with a satisfying click like an automotive spark plug wire.
Edit: I just found out that "Fan Speed High Lockout" really means the boiler cannot ignite after four (4) tries. After multiple resets, it won't ignite at all.
Walt
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