Fermometer Reading Seems Off

[JProulx]

I'm currently 36 hours into my fermentation. I'm fermenting 2.5 gallons in a 4 gallon plastic water jug (#1 plastic). My jug is inside of a 5-gallon metal pot, in a box, in a dark corner of the room. The fermometer is horizontal on the jug, about 4 inches below the top of the liquid.

Ambient temperature is 72F. I pitched my yeast at 58F. There is a huge, healthy krausen having a good time in there, and my fermometer is reading 66F.

Is there any reason why my fermometer would be 6F below ambient? Is it just because I pitched at 58F, so it's taking longer to rise in temperature? It seems like 36 hours, combined with the energy released by fermentation, would heat up the beer...

 

[unionrdr]

Pitching at cooler temps & letting it rise is better than the reverse. It'll hold a cooler temp than ambient for a while,which is good. You don't want it to go up to ambient or higher if you can avoid it. Except for saisons & wheat ales.

 

[JProulx]

Pitching at cooler temps & letting it rise is better than the reverse. Iy'll hold a cooler temp than ambient for a while,which is good. You don't want it to go up to ambient or higher if you can avoid it. Except for saisons & wheat ales.

So it's actually normal to take 36 hours (including 18 hours of heavy fermentation) and still not hit ambient? Interesting.

I'll be swamp cooling it if the temperature rises anymore.

 

[Yooper]

So it's actually normal to take 36 hours (including 18 hours of heavy fermentation) and still not hit ambient? Interesting.

I'll be swamp cooling it if the temperature rises anymore.

No, I think the reading is wrong. I wouldn't think that it would take that long to warm up. You can check it with a thermometer to know for sure!

 

[unionrdr]

Under most conditions,sure. But my 2 batches fermenting now used cold spring water out of the garage that took mine down to 64F. Didn't go above 68-69F the whole time of initial fermentation. But I kept the room a bit chilly as well.
I liked how the WL029 yeast is a slow to medium,very steady fermenter. It didn't go hog wild & make a lot of heat like some other yeasts I've used.

 

[Varmintman]

Location, location, location. Where the fermenter is makes a huge difference as well. During the winter the closet in my office stays right at 63 degrees making it a great place to ferment. Now I keep the office right at 70 degrees and both measuring points are within 5 foot of each other. The closet is a open faced closet so the only difference would have to be that the fermenter sits on the carpet in the closet and the other thermometer is half way up the wall.

 

[JProulx]

Location, location, location. Where the fermenter is makes a huge difference as well. During the winter the closet in my office stays right at 63 degrees making it a great place to ferment. Now I keep the office right at 70 degrees and both measuring points are within 5 foot of each other. The closet is a open faced closet so the only difference would have to be that the fermenter sits on the carpet in the closet and the other thermometer is half way up the wall.

I checked the temperature in that corner about 20 minutes ago. It looks like it's actually closer to 66-68F in that corner. To me, that looks like the reading on the fermometer might be accurate.

I've still draped a shirt over it and put it in water. I know you can't submerge a fermometer or it breaks, but is it okay if the wet T-shirt from the swamp cooler is touching it?

 

[Varmintman]

I checked the temperature in that corner about 20 minutes ago. It looks like it's actually closer to 66-68F in that corner. To me, that looks like the reading on the fermometer might be accurate.

I've still draped a shirt over it and put it in water. I know you can't submerge a fermometer or it breaks, but is it okay if the wet T-shirt from the swamp cooler is touching it?

If you mean one of the fish tank types I would think it is fine. Mine get soaked about every week when I clean the fermenter.

Now I use a indoor outdoor thermometer. The kind that you put the sending unit outside and it sends the temp to the unit in the house. I just seal it up in a plastic bag and set it on top of the fermenter. I can tell what is going on pretty much with just a glance now and do not need to bend down and see what the temp is.

 

[unionrdr]

I try not to let the wet tee shirt touch the stick on thermometer strip just in case.

 

[JProulx]

Thanks for the help everybody!