I'm having no luck finding an odor source in the house,

a smell of rotten eggs (or sulfur?) coming out of my heat vents in the winter.

this all started 2 years ago, I had a new heating system put in, a Trane, Electric Furnace and heat pump and A/C. A few months before, I also had a new hot water heater put in a Rheem Powervent, propane hot water heater. These are the only major changes made before the start of the smell. I attribute the issue to one or the other.

on to the smell,

the smell usually occurs very early in the morning, after my shower (hot water heater has been running), smells for about a few minutes and dissipates very quickly, about a minute. I've smelled the odor at other times, during the night, and during the afternoon, I've smelled the odor coming out of the sink (on septic, last pumped about 2 1/2 years ago), I've noticed the smell in my water, which leads me to believe I'm crazy, but family members have verified, I haven't noticed the odor in the summer when the furnace/ heat pump is not used nor have I noticed the smell in the air return vents. I have not found any dead animals (i.e. mice) in the ducting anywhere

water comes into the tank from the well, goes into a softener (doesn't smell like odor) , then to a hot water

heater, then to the pipes. I'm not quite sure, if it were the water, how it would transpose into the heating system.

There is no history in this area that I am aware of that documents sulfur in the water. my research shows this as a possibility. sulfur accumulates in hot water heater as it sits idle overnight, released when the water heats.

We've taken to bottled water for drinking, have had no ill effects from drinking tap (I make coffee with it every day)

and a well test is probably overdue.

I also might add,

I have dual zones, one downstairs, one upstairs, I have no smell or issues upstairs.

the guy that installed the furnace is now retired.

Rereading my post, seems I've accused the water system as being the issue, the heating system is much simpler, basic heat pump outside, furnace and fan inside to circulate the warm air.

any ideas on how to track down the source of the smell.

tia