RTD probe experiment...

[680bear]

So just a quick history about me,,, I am a commercial/industrial journeyman electrician that has a bit of experience in control and instrumentation... I have an old RT680 that I just installed the newest wifi controller in (firmware version 105) I was AMAZED how it locked in on temp,,, so amazed I was skeptical... So being OCD me I (like alot of us have done) placed my thermoworks smoke ambient probe right below the RTD and got the real scoop... temps @ 250 were 30 to 35 degrees off ... No problem right just use the offset adjustment and got it within 7° or so,,, that is until I started raising the temps,,, then the margin grew again... for awhile that was fine,,, I kept a note pad with the offset settings and entered them before every cook... But then I though why,,, why is the offset changing... So I looked around and researched what the other popular builders were using for controllers and RTD's ... The one thing I found is most other brand grills use a shorter probe,,, 4 inches instead of the 6 1/2 that RecTeq uses... So I bought a couple,,, one from Savannah and one from Amazon that said it's a replacement for I think it was for the big pit boss,,, They are both 4" and have the same ohm range as the one in my RT680 (which was replaced new with the controller ) What I found was very interesting in my testing... Temps were rock solid on the unit as before,,, what was different was in the offset,,, I adjusted it @ 250 to match as close as I could to my thermoworks unit and it held that setting all the way to the 400° where I was cooking,,, and the temp swings on the thermoworks probe where they were up to 25° difference are now around 10°... I will be doing more testing and will update the results if there is some interest... I am running the pit boss probe right now and like the results and will probably leave it in...

 

[ccmjr77]

Could it be just a bad RT probe? Did you compare to another 6.5" probe? The testing is interesting and when/if I need to replace my probe, I will definitely refer back to this thread. Thank you for posting your findings so far.

 

[680bear]

this all started because of a bad probe,,, it would read over 600° on start up,,, I ended up with 3 new ones from RecTec due to shipping errors (mail in our area is always getting "lost") I tested 2 of those 3 and they all performed close to the same... I figure the poor performance of the RecTec probe could due to being a cheap chinese supplier... just my thoughts...

 

[jaspry]

So just a quick history about me,,, I am a commercial/industrial journeyman electrician that has a bit of experience in control and instrumentation... I have an old RT680 that I just installed the newest wifi controller in (firmware version 105) I was AMAZED how it locked in on temp,,, so amazed I was skeptical... So being OCD me I (like alot of us have done) placed my thermoworks smoke ambient probe right below the RTD and got the real scoop... temps @ 250 were 30 to 35 degrees off ... No problem right just use the offset adjustment and got it within 7° or so,,, that is until I started raising the temps,,, then the margin grew again... for awhile that was fine,,, I kept a note pad with the offset settings and entered them before every cook... But then I though why,,, why is the offset changing... So I looked around and researched what the other popular builders were using for controllers and RTD's ... The one thing I found is most other brand grills use a shorter probe,,, 4 inches instead of the 6 1/2 that RecTeq uses... So I bought a couple,,, one from Savannah and one from Amazon that said it's a replacement for I think it was for the big pit boss,,, They are both 4" and have the same ohm range as the one in my RT680 (which was replaced new with the controller ) What I found was very interesting in my testing... Temps were rock solid on the unit as before,,, what was different was in the offset,,, I adjusted it @ 250 to match as close as I could to my thermoworks unit and it held that setting all the way to the 400° where I was cooking,,, and the temp swings on the thermoworks probe where they were up to 25° difference are now around 10°... I will be doing more testing and will update the results if there is some interest... I am running the pit boss probe right now and like the results and will probably leave it in...

I am VERY interested in this after noticing some of the same on my 700. Thanks for putting in the work!

 

[TheGuto]

Definitely noticed the same on my 590 - I did test my two removable RT probes in a cup of ice water and they were on point (32 degrees F). On my cooks, the grill grate level always measures hotter than the built in probe, and the left side grill grate is cooler than the right side, and it's off by about 20-25 degrees on most cooks that are between 210-250 degrees. All the while the probe that is built in to the left side and sticking up in the chamber is measuring dead-on what I have it set to...

 

[680bear]

I had no issues with the meat probes (I have the upgraded version),,, it was the RTD that was not giving consistent readings,,, I am thinking the shorter RTD that I have installed is giving a better result as it is reading closer to the cooking surface...

 

[Waterboy]

@680bear were the Thermoworks temps higher or lower than the Rec Teq RTD? Also do you have a link to the replacement RTDs? Very interested in the information.

 

[TheGuto]

Yeah, I would be interested as well!

 

[680bear]

they were lower at low temps ( initial start up ) by about 15° ,,, buy the time the grill stabilized set at 200° the thermoworks read around 8° high,,, and the gap grew from there,,, set at 250° the gap was almost 25°... and at 375° the gap was 80°... and that is with the thermoworks probe placed in its clip right beside the RTD... So far I haven't experienced any of this with the shorter RTD... This weekend I am going to continue my testing by moving the thermoworks probe to the center of the cooking surface and see the differences... I am expecting there will be a difference ,,, but I am hoping the temp gap will be consistent throughout the temp range like it is now with the thermoworks probe right next to the RTD,,, and then a quick one time offset adjustment will take care of it...
This is the RTD I have installed at the moment...

Replacement RTD High-Temperature Meat Probe Sensor, Barbecue Waterproof Probe Sensor for Pit Boss Probe PB1000XL-025-R00 https://www.amazon.com/dp/B085MBYFG...a_i_CK9SCK3DN7221DBA402B?_encoding=UTF8&psc=1

 

[Hawaiianbrian]

So just a quick history about me,,, I am a commercial/industrial journeyman electrician that has a bit of experience in control and instrumentation... I have an old RT680 that I just installed the newest wifi controller in (firmware version 105) I was AMAZED how it locked in on temp,,, so amazed I was skeptical... So being OCD me I (like alot of us have done) placed my thermoworks smoke ambient probe right below the RTD and got the real scoop... temps @ 250 were 30 to 35 degrees off ... No problem right just use the offset adjustment and got it within 7° or so,,, that is until I started raising the temps,,, then the margin grew again... for awhile that was fine,,, I kept a note pad with the offset settings and entered them before every cook... But then I though why,,, why is the offset changing... So I looked around and researched what the other popular builders were using for controllers and RTD's ... The one thing I found is most other brand grills use a shorter probe,,, 4 inches instead of the 6 1/2 that RecTeq uses... So I bought a couple,,, one from Savannah and one from Amazon that said it's a replacement for I think it was for the big pit boss,,, They are both 4" and have the same ohm range as the one in my RT680 (which was replaced new with the controller ) What I found was very interesting in my testing... Temps were rock solid on the unit as before,,, what was different was in the offset,,, I adjusted it @ 250 to match as close as I could to my thermoworks unit and it held that setting all the way to the 400° where I was cooking,,, and the temp swings on the thermoworks probe where they were up to 25° difference are now around 10°... I will be doing more testing and will update the results if there is some interest... I am running the pit boss probe right now and like the results and will probably leave it in...

Hey there got a question. I have RT680 restored it from being rust bucket. When your testing did you also put meat in the smoker? That may contribute to the offset of the barrel temp? I’m doing the same plus/minus 10 degrees. Comparing to thermoworks smoke probe which 3” shorter than says 6” rtd. I like the research and details you provided

 

[okie]

they were lower at low temps ( initial start up ) by about 15° ,,, buy the time the grill stabilized set at 200° the thermoworks read around 8° high,,, and the gap grew from there,,, set at 250° the gap was almost 25°... and at 375° the gap was 80°... and that is with the thermoworks probe placed in its clip right beside the RTD... So far I haven't experienced any of this with the shorter RTD... This weekend I am going to continue my testing by moving the thermoworks probe to the center of the cooking surface and see the differences... I am expecting there will be a difference ,,, but I am hoping the temp gap will be consistent throughout the temp range like it is now with the thermoworks probe right next to the RTD,,, and then a quick one time offset adjustment will take care of it...
This is the RTD I have installed at the moment...

Replacement RTD High-Temperature Meat Probe Sensor, Barbecue Waterproof Probe Sensor for Pit Boss Probe PB1000XL-025-R00 https://www.amazon.com/dp/B085MBYFG...a_i_CK9SCK3DN7221DBA402B?_encoding=UTF8&psc=1

I have both a 590 and a B380. The 590 has the long probe but is fairly accurate at low and high temps. The B380 has been a constant erratic temp performer. I use it only for hot, and sear cooks, and it is fine for that. It has a short RTD that is below the grates and gets direct heat from below. While I have been able to get some improvement in temp accuracy with the Offset, it has still shown erratic swings in temp at the lower settings. A recent trial of ceramic briquets to hold and stabilize temps was a total failure. I wonder now if it might be the RTD used is of poor quality and may contribute? I have considered that the control is of poor quality and has delayed response to temp swings, thus over and under compensating. But could it be the RTD? It is a short unit but I am not confident in its placement. I suspect there is no other practical place to put it due to the shape of the 380. Your thoughts?

 

[680bear]

Yes,,, I did a rack of spare ribs before I changed the RTD,,, results were close to the same,,, and I did a bunch of chicken after the RTD change and my results were almost identical to what I found with no meat... I am almost thoroughly convinced that the original RTD probes that come in our smokers are too long and are of inferior quality...

 

[680bear]

I have both a 590 and a B380. The 590 has the long probe but is fairly accurate at low and high temps. The B380 has been a constant erratic temp performer. I use it only for hot, and sear cooks, and it is fine for that. It has a short RTD that is below the grates and gets direct heat from below. While I have been able to get some improvement in temp accuracy with the Offset, it has still shown erratic swings in temp at the lower settings. A recent trial of ceramic briquets to hold and stabilize temps was a total failure. I wonder now if it might be the RTD used is of poor quality and may contribute? I have considered that the control is of poor quality and has delayed response to temp swings, thus over and under compensating. But could it be the RTD? It is a short unit but I am not confident in its placement. I suspect there is no other practical place to put it due to the shape of the 380. Your thoughts?

I don't think there is a delay built into the controller because after I swapped out the RTD the temp during preheat would climb degree to degree with my thermoworks probe... the most accurate RTD probes are made out of platinum,,, I don't think the RecTec probes are,,, I haven't cut one open to have a look,,, but they definitely don't act like the platinum probes I have dealt with in the past...

 

[okie]

I don't think there is a delay built into the controller because after I swapped out the RTD the temp during preheat would climb degree to degree with my thermoworks probe... the most accurate RTD probes are made out of platinum,,, I don't think the RecTec probes are,,, I haven't cut one open to have a look,,, but they definitely don't act like the platinum probes I have dealt with in the past...

Well the RTD in 380 is short rather than long, but is suspect you are right about the platinum. Might be worth the effort to change out the probe with a platinum short probe (if I can find one.) No hurry but if I do I will report results. Thanks for the insight.

 

[Hawaiianbrian]

Yes,,, I did a rack of spare ribs before I changed the RTD,,, results were close to the same,,, and I did a bunch of chicken after the RTD change and my results were almost identical to what I found with no meat... I am almost thoroughly convinced that the original RTD probes that come in our smokers are too long and are of inferior quality...

Thanks. For info. I’m sure your right. Since the thermoworks temp probe is much smaller. I’ll watch for your updates. Thanks from Hawaii...

 

[sdynak]

Although I have not done any experiments with temps as for the most part I don't recognize any issues (which may just be me being simple), I am interested in what is found further just as info and for future. If there is room for improvement in an already great product why not . Especially at such a low cost.

 

[Bradd1146]

I have also done the same and I was ridiculed on a FB group by several for doing so... the fanboys got upset I guess. RecTeq even saw my post and emailed me and said the RTD probe takes an average ambient temp. Which makes sense so the controller feeds the right amount of pellets I guess. But I also was very skeptical and see lots of people sing praise after praise over these dead locked temps. Well, they aren't deadlocked at all. I don't think any pellet grill can be that accurate due to the fuel source being used.

Another person said my test was flawed because my probes were on the grates. Well, news flash that's where the important temp is at because that's where the food is !

I still love my 590 but anyone who thinks these temps are that accurate is very gullible

 

[okie]

I don't think there is a delay built into the controller because after I swapped out the RTD the temp during preheat would climb degree to degree with my thermoworks probe... the most accurate RTD probes are made out of platinum,,, I don't think the RecTec probes are,,, I haven't cut one open to have a look,,, but they definitely don't act like the platinum probes I have dealt with in the past...

I notice that the platinum probes are labelled PT100. Does that require some sort of reset of the PID controller? If so how? also the short ones I have found require a larger drilled hole and are held on with a large nut.

 

[C. Keeper]

I notice that the platinum probes are labelled PT100. Does that require some sort of reset of the PID controller? If so how? also the short ones I have found require a larger drilled hole and are held on with a large nut.

To the best of my knowledge they are not interchangeable with our grills. In the automation world we can "program" for the different temperature devices and range.

 

[okie]

To the best of my knowledge they are not interchangeable with our grills. In the automation world we can "program" for the different temperature devices and range.

That being the case I will not pursue a platinum probe, but would be interested in installing the short probe that is available for PB. (aftermarket). I will just have to snip off the connectors to modify for the Bullseye control board. Or make an added connector. Will delay until pleasant weather. Cheap easy experiment.