Smell at base of toilet ONLY during mild temps (around 60 degrees)

[dglsconklin]

Bought a 1950s Cape last August and immediately remodeled the main floor bathroom. Put a new toilet in (a cheap dual-flush model from Sam's Club--which might be the problem but I'll continue) and had some water around the base after a few days. Since the pipe is cast iron leading to PVC in the basement, I changed to an Oatey 4 inch cast iron replacement, which has the Allen screws inside to form a tight seal. Got a thicker ring as well and it formed a good seal and I've seen no water.

For the next month or so, I noticed sewer smells on and off at the base of the toilet, but never any water on the floor. I started to notice that the sewer smell was only noticable on days when the outside temperature was around 60 degrees. When fall turned to winter and the temp hovered around 40, the smell went away completely. Kicked up again in Spring. I redid the caulk at the base of the toilet at the beginning of summer, but the smell was fading at that point anyway. Now I'm sitting here on a crisp late-summer day and it smells again.

At this point I have to think the smell is directly related to the temperature because it didn't smell all summer until today, the first day it dropped below 70 degrees. Does this make sense? Something to do with the vent pipe? It's driving me crazy, and I'm not against calling a plumber but if it's something I can do myself I'd rather. Thanks all!

 

[Reach4]

Bought a 1950s Cape last August and immediately remodeled the main floor bathroom. Put a new toilet in (a cheap dual-flush model from Sam's Club--which might be the problem but I'll continue) and had some water around the base after a few days. Since the pipe is cast iron leading to PVC in the basement, I changed to an Oatey 4 inch cast iron replacement, which has the Allen screws inside to form a tight seal. Got a thicker ring as well and it formed a good seal and I've seen no water.

For the next month or so, I noticed sewer smells on and off at the base of the toilet, but never any water on the floor. I started to notice that the sewer smell was only noticable on days when the outside temperature was around 60 degrees. When fall turned to winter and the temp hovered around 40, the smell went away completely. Kicked up again in Spring. I redid the caulk at the base of the toilet at the beginning of summer, but the smell was fading at that point anyway. Now I'm sitting here on a crisp late-summer day and it smells again.

At this point I have to think the smell is directly related to the temperature because it didn't smell all summer until today, the first day it dropped below 70 degrees. Does this make sense? Something to do with the vent pipe? It's driving me crazy, and I'm not against calling a plumber but if it's something I can do myself I'd rather. Thanks all!

I suspect that you want to re-do the wax, or switch to a waxless seal. When you lift the toilet, pay attention to how well the seal looks like it might have been sealing.

When you put in wax, it is important to only compress and not decompress the wax. So if you will put in shims, have them in place before dropping the toilet. It is also possible that you needed two wax rings or an extra-large wax ring. The waxless seals have the advantage that you can de-compress them during install to an extent, without harming the ability to seal. I think the less experienced person can benefit even more than the experienced person from that ability of the waxless seals. Wax has its advantages. It can conform to anything.

Also, if you use a plunger, the wax is more likely to blow out than a waxless seal should. If you need to plunge, there is something not quite right. There could be some blockage in the soil pipe leading from the closet flange. It could be a toilet that is not up to current performance expectations.

As far as the smell only occurring in particular temperatures, maybe different organisms grow in your septic during parts of the year. Or maybe the wind patterns tend to be different and the wind patterns somehow partially correlate with the temperature. Maybe your AC and heating apply a positive pressure to the house. During mild temperatures, you may turn off the heat and AC, or you might even open a window that creates a different air flow pattern. That is speculation, and it does not matter regarding the cure.

You want to replace the seal.

 

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[Smooky]

Instead of a temperature decrease causing the odor, it might be a result of a humidity increase. When the temperature drops the relative humidity increases. Humidity increases our ability to detect odor. Usually an increase in temperature cause an odor to be stronger and as it gets colder the odor would be less noticeable.


Before you tear anything up, you should get down, scrub the base of the toilet and clean the floor all the way around. Maybe somebody missed the target and that is where the odor is coming from.

 

[Plumber69]

I get a sewer smell sometimes to. But it's cause my vent pipe is to close to my window. And only happens sometimes. Of course my window is open when I smell it

 

[dglsconklin]

I've cleaned the floor with an assortment of cleaners, including under the toilet when I took it off to install the second flange/wax ring. Our house doesn't have central air and only has window units upstairs, but they haven't been running today so I don't think that's our issue.

I've read around that others have had issues with gasses coming up around the flange for incorrect types. My flange seemed to form a tight interior seal to the pipe--I tightened the allen bolts as hard as I could without stripping them and couldn't even budge the flange after. Still wouldn't explain why I don't smell it in the summer or winter, unless Smooky's suggestion that it's a humidity issue, not a temperature issue, is true.

Our vent pipe runs to the roof, which is why I initially thought it might be a clog or something to do with the change in temperature trapping gasses.

Only other thing I forgot to mention--when put the toilet down the second time I ran out of plastic shims and used a stack of dimes in a pinch. Before I put in the silicone around the base I pulled the dimes out to replace with a shim and they were very oxidized--practically all green. Is it normal to have that much humidity underneath the toilet?