I have a Bryant Plus 80 furnace with a heat pump-A/C combo; typical 2-story house design with basement - age: 4-5 years.
From a previous discussion here (based on the SEER rating), the A/C compressor isn't large enough to meet the cooling demand. So, if we use the stove, I have to open the damper to the kitchen to cool that area, and close it up to give the main-floor and upper-floor areas. The temp creeps higher from the setpoint until the sun goes down. Technicians have been out for various problems, and apparently it's "just how it is".
Tonight I noticed a damp, white crystalline substance that had dripped on top of the furnace door. It's coming from the main furnace vent at the first pipe connection. It doesn't have a smell and looks to heavy in mineral content. It forms like an icicle or cave drippings.
We just returned from a 9-day vacation where the hot water tank was set to "vacation". The furnace gas vent enters a Y connection by the hot water tank and up to the roof.
I fired-up the burner to see if there were any blockages. I smelled some natural gas, but probably normal.
So, what could this stuff be? Any concerns?
Thanks in advance...