Jon, you lost me at RTD
I’m an old EE, but maybe CRS has taken over....explain RTD and what you are trying to do, and if it’s before my 3rd V&T, maybe I can help!
My fireboard rtd probes mounted in my PBC seem to be wildly inaccurate below 50F. Above that they seem fine though.
Not much help help as I don’t have any calibration evidence, just observations since I have several other probes in the cooker and check occasionally when the rig is off.
If I can find my DMM I’ll take a look but that’s a big if at the moment.
Is the probe removable and what plug is on the end of it is? Fireboard lets you specify the type of probe so if you had or borrowed a fireboard you could check it that way also.
If it is a standard probe replacing it probably costs less than the effort :-). Of course that may not be the problem either.
Polarbear777 thank you so much for your reply’s. This is not a temp monitoring kind of question. It more of how a pellet cooker controller, pid or analog talks to the rtd that gives the temp inside the cook chamber.
As for effort? I’ll put the effort in to understand the issue anyway. ; )
Last edited by Jon Solberg; April 16, 2018, 07:35 PM.
So I guess what you are telling us is that your pellet pooper is running wild not matter what the temp setting is? I do know this about resistance-the hotter a given electrical component is the higher the resistance though that component. I am not sure what you are trying to diagnose. I had a pellet grill that did that to me and I replaced the temp sensor inside the cooking chamber and that took care of the problem but I am not sure of your specifics.
Im trying to test the temp prob which is an RTD type probe. Yes it’s in a pellet rig. I don’t want to replace the rtd if it’s not bad. It’s not a standered of the shelf rig. I’m just trying to get a better understanding of how to diagnose rtds in general. I understand the principle of heat and resistance. That is not related to my question here but a great point. Thank you for sharing it vandy
Last edited by Jon Solberg; April 16, 2018, 06:55 PM.
I have two threaded RTD probes in the pbc. Now that you have me looking, I see one is registering 90 degrees while every other thermo (all 10 of them) are registering mid 40s.
Maybe they arent as robust as advertised. I may have to go get the multi meter.
looks like it should read the spec value at 0 C, and about 4% increase for every 10 C, at 19 C should read bout +8% (looks linear on chart), so 136 ohms at 19 C seem high, should read 108 ohms if it is a 100 ohm spec unit
thats mt initial guess
Dang! I was just about to say that. Maybe I should get a hat like that to warm the blubber around my head and increase blood flow efficiency thereby creating....well... just a good looking hat.
Jon, you stated rtd is calling for heat no matter what temp the cooker is. If rtd resistance goes up with temp, then I would think the pellet controller adds pellets inversly proportinal to rtd resistance. So if the rtd resistance is to high, the controller would slow down the pellet auger and cool down the cook. I think the rtd would have to be lowresistance for the auger to feed continuously. So if your rtd is a 1000 ohm reading 136 ohm, that would put pellets to the fire. If your rtd is a 100 ohm reading 136 ohm that would turn off the pellet auger and its not, so something else is going on, bad controller?
hope that made sense, again, I’m guessing with little knowledge here but maybe the thoughts will help
ohms are one of the most fundamental parameters of electricity along with amps and volts. One volt applied accross one ohm of resistance will allow one amp of current to flow. Some german smart guy discovered the relationship, he was kinda an early Meathead so to speak.
Well Jon, you can throw most of what I said out the window! Just for grins, I ohmed out rwo rtd probes, one camp chef and one smoke. At 23 C they read 109-113 K ohms. When I put my hand on the probe they both DROPPED resistance to about 91-94 K ohms , figure body temp bout 98 F or 38 C.
So the resistance of my two different probes is inversely proportional to temp. hope those numbers give ya somthin’ to compare two, good luck! K means x 1000
If not cooking outdoors, I am cooking on the stovetop with my 14" carbon steel wok, 12" CI skillet, or in the oven with my two Lodge CI pizza pans, or two dutch ovens. I've also got a nifty Lodge carbon steel grill pan that rocks for veggies outdoors.
I cannot speak to this particular RTD, but most of the temperature sensors I've worked with are thermistors, which have the specified resistance at 25C (room temp in a slightly warm room) and the resistance decreases as the temperature increases. We really need to know the nominal value for your RTD, which would be given by its datasheet at a specific temperature.
you kiddin’? I remember when statics and dynamics was the weeder class.....freaky wierd science! but, then there was thermo dynamics.....give me electrons for breakfast!
Hi, my name is Darrell. I'm an OTR truck driver for over 25 years. During my off time I love doing backyard cooks. I have a 48" Lang Deluxe smoker, Rec-Tec pellet smoker,1 Weber Genesis 330, 1 Weber Performer (blue), 2 Weber kettles (1 black and 1 Copper), 1 26" Weber kettle, a WSM, 8 Maverick Redi Chek thermometers, a PartyQ, 2 SnS, Grill Grates, Cast Iron grates, 1 ThermoPop (orange) and 2 ThermoPens (pink and orange) and planning on adding more cooking accessories. Now I have an Anova sous vide, the Dragon blower and 2 Chef alarms from Thermoworks.
Comment