Drain smell when intermediate heat is on!!? When I put the central heat on, not all the time but...
When I put the central heat on, not all the time but plenty to bother me, there is a smell of drains surrounded by my house!
Why is this and what can I do about it??
Answers: It is call believe it or not "dirty sock syndrome" and over time will get worse. Get an HVAC personage to come and clean your coils and it will find better, but don't be surprised if it never goes completely away.
Sounds close to you need your system flushed. The hose down in a centralized heating system go black and brackish eventually.