I used it in the bathtub, & another time in the basement suds tub, the whole house would smell. Last year I checked the vent pipe on the roof & removed a lot of old paper wasp nests, but am still having the problem.
Plumbing – When I use drain cleaner the whole house smells like sulfur for a couple hours
plumbing
Related Solutions
You must have a vent. The toilet will not flush properly without one, and there will rarely be enough water left in the bowl. You need a 2" vent to take off from the branch line within 6 feet of the toilet. It can run up any convenient wall until it is above the toilet's flood level. Then it can run near horizontally (1/4" per foot) anywhere to tie into an equal or larger vent.
There's any number of ways to properly vent a toilet, and several common ways that are technically wrong, and even more that are just plain wrong. It's impossible to suggest a good method without a lot more information.
Why do you think the bathtub is not currently vented?
Not all traps need to be individually vented so you're not always going to see a vent if you don't know what to look for. It's a little hard to tell from your photos, but I think your bathtub is wet vented through the kitchen sink:
Please correct me if I've got the arraignment of your pipes wrong.
Best Answer
I would advise against Drano. The sulfur smell you are smelling is because it is mainly composed of Sulfuric Acid. If you smell it throughout your house it might be damaging your pipes.
To clear a clog I would recommend a plunger and a drain snake before resorting to any acids. If those do not work I would recommend a plumber.
However, be cautious now. If you are manually clearing your pipes, anything that you pull out might be covered in acid, so make sure to use hand, eye, and nose/mouth protection.