Nursing my 18 year old Lennox Pulse 21 furnace
Has been reliable for the past 10 years that we've owned this house. Recently been having a few no starts.
Called my maintenance company = long story short, it was the ignition control board. Originally quoted a price, was then called back and that they were not available, but could be had for 3x the original quote and then they wouldn't cover the furnace any more. So I got one on the internet which I bought for 0.5x of the original quote and 1/6th of the second! This fixed the problem initially. Then the no start became intermittent. Have now changed the air flapper and spark plug. New flame sensor on the way. Plug and sensor threads looked rusty so used some dialectric grease. Removing the plugs is possible without using the special lennox tool. I used a plug socket with a short adapter that adapts the socket to a hex bolt and then a wrench on that bolt. Takes a little patience but quite doable. Waiting on a new flame sensor. Have not changed the gas flapper. The maintenance guy checked and adjusted the gas pressure and seemed to think the gas supply and value was OK.
Have not been having any lock outs now but do notice that the furnace always seems to start on the third of the five ignition cycles before lockout. Is that normal? Almost seems like it takes 3 ignition cycle for the right air/gas mixture to be present at startup. Once running everything seems fine.
Been interesting to see how these work. Seems pretty bulletproof if the common problems are addressed and are pretty easy to work on with a service manual (downloaded) even for an amateur. From what I could see with a mirror the HX etc looked in reasonable condition.
So if the 3rd cycle start normal?
Have quotes for a new system but on principle want to keep the old girl running or at least want to get thru to spring when prices may be lower and rebates may be available. Considering a Trane XV95 and 3 ton heat pump (XL15i). Seems my location (NoVA) is marginal for heat pumps though.