Greetings folks, hoping someone can shed some light on a heating problem. The above named furnace has been working flawlessly for 16+ years ( other than a thermocouple replacement), natural gas forced hot water with 4 zones. We recently added a 5th zone ( basement ) and the additional zone works occasionally at best. Replaced the thermostat, also swapped TACO valves between zones but the problem remains. Symptoms are, thermostat is turned on, furnace kicks on but burner never fires. Once or twice when the burner did fire, no heat was sent to the zone and the furnace shut down a minute or two later. Could it be the valve is not opening? I'm stumped at this point, all other zones working fine. Thanks in advance for any/all info. BuddyD

Hi Last night my family and I smelled a burning smell similar to what you smell when you first fire up your furnace in the fall. I thought maybe it was the filters needing cleaning and resolved to do that today. Woke up this morning the furnace had stopped working sometime over night. What I know so far: Approximately 13 year old Lennox furnace- serviced regularily I powercycled the furnace. Got two slow blinking lights Blowers kick on I hear ignition Stays lit for a brief time (under a minute) Recieved two different codes (after cycling had second code) First i got Low Flame Signal, Check Flame sensor. 15 minutes later, the furnace tried to light again on its own and i got Primary/Secondary limit switch open Now its sitting at watchguard burners failed to ignite. Whats my next step?