My only problem with my Heatermeter. (Minor)

[Paul J H]

Hi everybody.
I wanted to post here and see if there is anyone with a suggestion to help me with my only real problem with my Heatermeter.
When I lift the lid to baste or turn my meat, the lid open setting triggers and shuts the fan and damper down as it is supposed to.

When I place the lid on again, because of the 120 second setting in the default it means that my fire is smothered for a period.
I know I can cancel the duration with a button push and I usually do that, but then the Rotodamper comes back on at 100% and the temperature continues to drop for some time.
I believe the fan blowing at 100% is actually killing my fire.
Eventually the fire does recover but it takes quite a long time... maybe 30 to 50 Minutes.
I have been doing some experiments with this and I'm currently running with my Fan output Max set to 50%.
That seems to have helped.
I have tried at 30 but that seemed to be making the fire too slow to respond during normal cooking.

My gut feeling is that what I need is to be able to ramp up my fan speed slowly after a lid open event.

I was talking privately to John Bostwick about this and he thought that the solution may be to use an alarm script to do what I want.

IF that is the solution, it would need to be done so that I could try different numbers, eg: first minute after lid open event Fan speed 10%, second minute fan speed 30%, 3rd minute 40%. (Damper set to 100% open) with those numbers able to be changed if they don't work.
I believe I would need to experiment with both the percentages and the durations.

I'm not even sure if this is the solution.
I have searched in this forum and I don't see any evidence of anyone else having the same problem, so perhaps I'm barking up the wrong tree completely.

The next issue is ... IF there is a chance that I'm right, I have no knowledge of writing scripts, so I'm wondering if there is someone who would be willing to write the script for me to do what I hope will solve my problem?
I'd be over the moon for someone to reply and say "No, the solution is simply this..."
Frankly that's my other thought... that there is something I'm missing... because I don't see anyone else having this problem.
Thanks for reading.
Cheers,
Paul.

 

[Steve_M]

It almost sounds like you need to bump up the lid open timer to more than 120 seconds so that when you put the lid back on, the bbq has more time to naturally bring itself back up to temp before the blower turns on to assist with things.

Also, if you're finding that 100% fan output is creating a problem, you can lower the max fan output in the heatermeter web config.

Looks like you've got some experimenting to do!

 

[Paul J H]

Hi Steve, thanks for the reply.
I am using a Weber Classic.
Although I didn't know it when I bought it, ( I thought I was buying a conventional Weber.)
I didn't know there was such a thing as a "Classic" version.
In my opinion it's misnamed anyway, (it is in fact a new version.)
I'm told that they are notorious for "snuffing" the fire out.
I'm told that its to do with different convection in the shallower bowl of the "Classic" version.
That's in fact why I was looking into the Heatermeter in the first place.
Before I modified it with the Heatermeter/RD3 Combo my BBQ would just slowly go out.

With out the fan going, the BBQ would snuff out, even more so now because I have attached the RD3 via a Dogs bowl over the intake holes.
With the fan off, even with the damper fully open, I believe the air intake is even more restricted.

Also, during the lid open mode the damper is closed, hence why I override it as soon as I have closed the lid.

Make no mistake, I'm VERY happy with the Heatermeter /RD3 combo. It has turned my BBQ from being basically unusable in to an extremely predictable tool.
What I'm doing now is simply a part of enjoying fine tuning it.
I'm enjoying the challenge of getting it exactly right.
I'm going to cook a pumped, marinated Beef Blade roast on the weekend.
I'm going to experiment with manually controlling the fan after lid opening events, but I'd prefer it to be a more automated process if possible.
Again Thanks for replying,
Cheers,
Paul.

 

[Steve_M]

When the HM and RD3 are running, what's the average output %? If it's under 10%, I would lower the max fan speed until you're averaging around 30% output to maintain the cook. If the fire is being starved to the point of almost going out with the bottom vents closed and the lid on, you might want to open the vent on the lid a little more.

 

[Paul J H]

As I said in my first post, I have played with the Max fan speed setting... and I'm currently running with it set to 50%.
When I first tried experimenting with changing Max fan speed I did set it to 30% and although I feel it did help with my issue of recovery from Lid open events, overall it seemed to be slow to respond to temp drops, so I set Max fan speed to 50%. I don't have any of my logs stashed, but I would say from memory that once temp is reached the average fan speed is around 30% (with Max Fan set at 50).
I have "Fan output Min" set at 10% and I only see that activated occasionally.

 

[Bryan Mayland]

I've thought about this and can't think of any way to easily ramp the output back up after Lid Mode. I don't think alarms even fire when in RECOVER mode, which is what occurs after lid mode ends. Lid Mode will end automatically if the temperature reaches the setpoint, I am not sure if you an use that information to your advantage any way.

It does sound like you're on the right track with setting the max fan speed to ~50%. If the fan actually decreases your pit temp, then obviously that is too high because then it will never reach temp no matter how hard it blows. You might try increasing your Lid Detect trigger point so that when you open the lid, the blower actually ramps up and stokes the coals a bit until it actually kicks in. That could cause an overshoot for most people, but this will give it a little extra oomopf before the damper is closed and the fire starts to dwindle.

I'd also look at extending your timer (240 seconds is actually the default). Set it to like 600 and then do a normal operation on your grill, raising the lid, doing some work, closing it up, and let the lid timer tick. Watch your graph and see if the temperature climbs when you close the lid. Watch where it peaks and that is roughly the point you want your lid timer to actually end, where the temperature is closest to your setpoint. You want to back it off a little from there because that's the point the fire is starting to go the other direction and you want to keep it climbing. However, if when you close the lid the temperature never climbs, then you're in trouble because your fire is actively trying to extinguish itself which means you need SOME amount of airflow during lid mode just to keep things alive. At that point you can try maybe setting your damper's closed position to be ever-so-slightly open? That's sort of uncharted territory.

 

[Paul J H]

Hi Bryan, My mistake ... the Lid detection setting IS at 240 seconds.
I haven't changed it at all.
When I open the lid and do what needs to be done, then close the lid, the temp does go up, but with the damper closed and the fan off, it begins to fall again.
I can't remember the times that it takes, but at that point with the damper closed and the fan off, the fire is basically unable to get any air at all so obviously it will snuff it out.
I'm quite sure that it needs air, but just a little till it starts to rebuild.

Seeing as I can't do it automatically, I'll just have to do it manually.
As I use and experiment with it, I'm getting more familiar with operating the controls of the Heatermeter, both on the unit itself and the web interface, so, when I do my next cook, (on the weekend) I'll just experiment with some manual fan control to recover from lid open events.
I'm pretty confident that I'll be able manage it manually with something like 10% fan for a minute or two then 20 or 30.
I'll try to save my log after I do my blade roast.
I tend to be so busy at the time I take the meat off that I don't get around to saving the logs.
I'll try to remember to save it just before I take it off.
I'll report back here how I go anyway.
Cheers,
Paul.