ThermoCouple/PID Issue

[Rich22]

Here is a weird one

Everything was fine after last casting session with my homemade (with much help from OB) PID. Went out last time and it seemed off a bit but I increased temp and it worked. Brought it in to check out and at normal room temp (approx 72 degrees) the unit is displaying -23 degrees F. Is it common for a TC to be off by that much? I am in process of getting another one to see if it is the TC or possibly I messed up something on the PID.

An addendum, after 2 minutes in the middle of a pot of H2O at a rolling boil it stabilized at 121 degrees F

[waksupi]

I had trouble with my probe when I first started out. Ordered two, have a spare on hand now. Once I replaced the original, no problems.

[Beagle333]

TC's do go bad. I'd buy half a dozen of em at a time if it were me. I have had a couple that came loose inside and another couple that just failed outright. Did you wiggle the wires to it and see if you could make it change just by jiggling the probe? That would be my first guess, would be bad probe. It would really help to have at least a backup, just for diagnosis of things like this.

[Rich22]

Just remembered I have one in my oven I can grab to at least check out the thesis of which is bad, far too large to use in my pot but it will tell me what is up most likely. Shall report back later. Appreciate the help guys

[dragon813gt]

Check at known temps. A glass full of water w/ ice cubes in it should read 32 F. And a pot of boiling water should read 212 F

[TexasGrunt]

Check at known temps. A glass full of water w/ ice cubes in it should read 32 F. And a pot of boiling water should read 212 F at sea level.

Fixed it for ya.

[dragon813gt]

Anyone at altitude should know they need to adjust temp accordingly.

[TexasGrunt]

I'll bet most don't.

[10x]

Check at known temps. A glass full of water w/ ice cubes in it should read 32 F. And a pot of boiling water should read 212 F

the boiling point of water will drop as you go up in altitude.
Measuring the temperature at which water boils was how the early explorers and surveyors estimated altitude. It worked very well.
I can't remember which map maker it was who recorded a disaster in his diary while surveying a river system - his thermometer broke and after that all altitude estimates were rough guesses.

[10x]

Anyone at altitude should know they need to adjust temp accordingly.

Wife's aunt moved to Calgary, (3500 asl) and discovered a 3 minute soft boiled egg takes 15 minutes at that altitude.

[dragon813gt]

I'll bet most don't.

Not my problem if they don't know simple science. I can't hold everyone's hand all the time. Seeing as how we're taking about PID thermocouples I'd hope people are smart enough to know what temp water boils at in their area.

[Screwbolts]

When checking TCs with boiling water, remember that water boils at different temps depending on the air pressure at that precise time! Altitude above sea level also effects air pressure. Take a known thermometer and see what the water boils at at that time along with what the TC reads.

Ken

[TexasGrunt]

Wife's aunt moved to Calgary, (3500 asl) and discovered a 3 minute soft boiled egg takes 15 minutes at that altitude.

Hm... is she an old wife? Water would boil at 205° at 3500 feet. Every 500° = -1° for the boiling point of water. I've lived at 5000 ft many times in my life and eggs take an additional minute or so.

[Rich22]

Never knew this would become a science thread when I started it. I'm at about 85 feet so 212 should be very very close