insulation for thermometer in brew kettle? thermometer face fogging/gets too hot!

sorry for starting a new thread, but this came up in another thread i had, and after searching all over here, and google, for several hours, i didn't find anyone else with this specific issue, so i decided to start a new thread to hopefully help me, and future problems for others.

i am building a keggle, and i installed my weldless bulkhead ball valve, and then i bought the blichmann fixed face weldless thermometer.

the first problem i had was i cranked it too tight, and split/broke the orange rubber o-ring, but that's not what this is about.

i got another o-ring, a black one from menards, have no idea what heat it's rated for, didn't crank it down as hard, and filled up the keggle with around 4 gallons of water, and it didn't leak. hooray! -but that's not what this thread is bout either.


i fired up my banjo burner, to test it all out for heat, and see how it would do. it was only on for a couple minutes, and i noticed the face of the thermometer was fogging up a bit. i touched the metal ring on the face of the thermometer, and it was super hot. like i couldn't hold onto it, it was so hot. the thermometer only read around 110*, and the water on the inside of the keggle was around that temp also. i could comfortably put my hand in the water, and it felt right around 100* but like i said, the outside of the keggle, the face of the thermometer was super hot, and the inside of it was fogging up.


i turned the burner off, and drained the keggle of the water, and it's been three days, and the inside of the thermometer is STILL a little fogged.

after getting pissed, and thinking i ruined a $40 thermometer, i think i made a major rookie mistake.

around the bottom skirting of the keg, there's little holes, and i put my thermometer right above one of those holes! i'm certain that heat is coming up right thru that hole, and making the thermometer face hot.

i have two questions. first-anybody ran into this before? i don't have any way to weld up the holes, if i had a welder, or access to one, i wouldn't have used weldless fittings. anybody got another fix idea for this? i thought about just putting the ball valve where the thermometer is, and put the thermometer where the ball valve is, since the ball valve currently isn't above one of those holes, but the ball valve is a 7/8" hole drilled, and the thermometer is only a 1/2" hole, so i don't know how i could do that, can't really make a hole "smaller', lol. then i thought if i bought a sight glass, i could put the sight glass where the thermometer hole is, and just drill a new hole for the thermometer somewhere else away from one of those holes, BUT i have no idea what size hole is common for a sight glass, OR if there'd be an issue with the heat on the sight glass, or if a sight glass is supposed to be put in on a specific height on the keggle. (i don't know JACK about sight glasses) also didn't know if there was a way of wrapping some sort of umm. "fire proof" insualation around the bottom of the keg, around the skirting holes, and/or around the thermometer face? don't even know if there is such a thing.

second-is my thermometer ruined? will it fog forever now, no matter what i do? will the fogging go away eventually all the way, and be ok? the instructions that came with the thermometer say pretty specifically if the face gets too hot it will fog, and that that is not covered under a warranty.

thanks in advance for any help/advice.

brian

The orange o-ring is made of silicone and will handle a lot more heat. The black one you replaced it with is most likely buna or butyl, will not handle near as much heat, will start to get hard and crack fairly quickly. It would be best to replace the o-ring with another one made of silicone. Not a big deal at the moment but something to think about.

As for the hole in the standoff... You have a couple of easy choices. Get a few washers and a bolt to close off the hole in the standoff and divert the heat stream somewhere else. If you use stainless steel hardware and a silicone o-ring, the same could be done with the thermometer hole and relocate the thermometer to a different location.

Moving the valve to the location above the heat stream would most likely cause a problem with the valve as it has polymer parts in it as well.

The thermometer may have drawn moisture into the housing. If you can take it apart, it would be easy enough to let it evaporate. If that doesn't work, put it in a ziplock bag with dessicant and that will eventually draw the moisture out. It would take a while. Drilling a small hole in the back of, or at the bottom edge of, the thermometer would speed that process up and could be filled with a small screw after the moisture is out.

If the fog is caused by a lubricant being overheated inside the thermometer, cleaning it out could be a real job as it will not evaporate. One could still drill a hole and clean it out with q-tips and alcohol. A hole in the edge at the bottom of the face would be the way to go on that one. Again, fill it with a small screw .

Photomask said:

The orange o-ring is made of silicone and will handle a lot more heat. The black one you replaced it with is most likely buna or butyl, will not handle near as much heat, will start to get hard and crack fairly quickly. It would be best to replace the o-ring with another one made of silicone. Not a big deal at the moment but something to think about.

As for the hole in the standoff... You have a couple of easy choices. Get a few washers and a bolt to close off the hole in the standoff and divert the heat stream somewhere else. If you use stainless steel hardware and a silicone o-ring, the same could be done with the thermometer hole and relocate the thermometer to a different location.

Moving the valve to the location above the heat stream would most likely cause a problem with the valve as it has polymer parts in it as well.

The thermometer may have drawn moisture into the housing. If you can take it apart, it would be easy enough to let it evaporate. If that doesn't work, put it in a ziplock bag with dessicant and that will eventually draw the moisture out. It would take a while. Drilling a small hole in the back of, or at the bottom edge of, the thermometer would speed that process up and could be filled with a small screw after the moisture is out.

If the fog is caused by a lubricant being overheated inside the thermometer, cleaning it out could be a real job as it will not evaporate. One could still drill a hole and clean it out with q-tips and alcohol. A hole in the edge at the bottom of the face would be the way to go on that one. Again, fill it with a small screw .

Click to expand...

i really would rather not just fill the current thermometer hole with a stainless plug, because it just is another possible future leak.

oh god, sometimes it's the simplest fixes isn't it? lol. i didn't even THINK about just putting a bolt through the skirting hole. it may be hard for my to get one inside there because of the bottom of the keg is right behind that hole, but when i get home, and my keg is in front of me, i'll try to fish a bolt through the hole, from the inside of the hole, to the outside of the hole, but on a few different sized washers, and then a bolt on the end of it. hopefully i can make that happen. i feel silly for not even considering that, lol.

A piece of aluminum flashing and a pop-rivet or two should shield the hole as well...