Testing Pellet BBQs & Pellets

[urbangriller]

Hi Gatsby,
We have already performed tests with the Yoders & thermal covers save around one third of pellet usage. The more you can protect the inside of your BBQ from the cold, the less pellets you will use, the more stable your pit temperature ( no temp big swings ) & the better your overall results.
Its my opinion that if tests are to be carried out, that testing & weighing for only 3 hours would not really produce accurate results, Bentley may correct me on this.
I believe that you only gain an accurate picture of usage & performance after a whole bag, after all who runs their BBQ at 200/225F for only 3 hours?
Cheers, Dave

I was running BBQ School yesterday so I was Off Air and this whole topic is a little confusing……it looks like Dave is answering a question in my vendor section?….perhaps it has been moved from there??

I don’t understand the criticism of the three hour Pellet Consumption test when I confirmed the validity of the results with a second test of 6 hour duration. You can see the results of those tests a bit further down this post.

Anyway, moving on:

I will be doing some testing with the thermal blanket on.

But I have to say that if your Pellet Grill is having temperature swings as Dave suggests, a blanket won’t fix that: your controller is not working properly or the unit has a mechanical problem. My GMGs have no temperature swings, they stays within 2°C of where I set them. My Traegers can be set to do similar by adjusting the P setting to customise the temperature and smoke management. Using a blanket insulates the Pellet Grill and therefore it will use less pellets.

The problem with testing based on cold startup is different brands use different approaches to reach target temp. Some deliberately overshoot then drop to the target temp to make start up quicker but is no doubt inefficient. In a test from cold, it will probably be the slowest cooker to warm up that is the most fuel efficient.

Start-up is the time a Pellet Grill takes to get to stable temperature; it overshoots then takes time to get down to the set temperature, that’s still start-up!
I’m interested in both, the time and fuel to get to stable temperature and the ongoing fuel demand to stay at set temperature.
Why would slow start-up influence the ongoing fuel needs?....it wont!

With regard to three hour consumption testing, logic tells you that if your Pellet Grill is using a significantly different amount of pellets at hour 4, 10 or 18, than it is at hours 1, 2 or 3, then it has a problem.

In fact the difference between the 3hr test and the 6hr second test I posted is 3grams per hour! Both tests were cold start and include the startup in the calculations. This is the same way Dave did the “entire bag” test in his Yoder YS480: cold start and amortising the cost of the start-up over the duration of the test. If anything, the cost of start-up amortised over only three hours is increasing the cost per hour, compared to amortising start-up costs over 18 hours.

Here is the test I posted:

I thought I’d run some tests in my GMG Jim Bowie.
The Jim Bowie has a grill size of 600 square inches. The Daniel Boone has a grill size of 432 square inches, (the Jim Bowie is 49% bigger) and we’ll run some tests on one of them as well.

First test:
Ambient temperature was 13°C (55.4°F) increasing to 17°C (62.6°F)
I put 4 kg of GMG Gold Blend pellets in the hopper and started the JB, set the temperature to 200°F (93°C) and turned it off 3 hours later. The JB had used 1.117 kg of pellets this equates to 372 grams per hour.

Second test:
Ambient temperature was 10°C (50°F) and bucketing down as it had been since 8pm the night before, it never got above 13°C (55.4°F).
I put 4 kg of GMG Gold Blend pellets in the hopper and started the JB, set the temperature to 200°F (93°C) and turned it off 6 hours later. The Jim Bowie had used 2.25 kg of pellets or 375 grams per hour.

GMG pellets come in a 28 pound (12.7kg) bag and have a retail cost of $35
1kilo of pellets is $2.75

Most Pellets come in a 20 pound (9.07 kg) bag, the equivalent weight of GMG pellets would be $24.95
375 grams of GMG pellets has a retail cost of $1.03

Based on an average consumption of 375 grams per hour the Jim Bowie would run at 200°F (93°C) for 24.01 hours on a 20 pound (9.07 kg) bag of pellets.

Bentley did a consumption test on the smaller Daniel Boone in 2009 for Pelletheads, the consumption at 200°F (93°C) came out to 312 grams per hour, you can read more here: http://pelletheads.com/index.php?topic=2156.0 In that test the GMG was run up to temperature before the pellets were added, so that’s a test I will do next.

Cheers
Chris

The three hour test is as valid as six hour or eighteen hour tests, but more to the point, it is an easy and cheap way anyone can test the performance of their Pellet Grill, without burning an entire bag of pellets.

For those who do want to burn a bag of pellets, or for those who want to get the true cost of a full cook, I have added that functionality into the spreadsheet calculator I spoke about in my vendor section. You can do a test of any duration you like, the Pellet Consumption Calculator will still provide a usage and cost per hour figure. It will also provide a cost of pellets used in start-up getting to a stable temperature if you choose to do that.

It does not matter how you do the test, if your results are different to other people with the same equipment then that points to a problem. The people here will look at the result, see it is out of whack with the norm and they’ll start to work out what might be wrong. This is exactly what happens with gassers, how many faulty hoses, blocked burners and jets have we found and fixed over the years?

The common misconception is that Pellet Grills are way more expensive to run, they are not: and Pellet Consumption testing confirms that.

You can download the Pellet Consumption Calculator here: http://wp.me/p4tQQY-10V

Cheers
Chris

[Santo]

Hey Chris, good points listed.

Im curious do you think the brand of pellets or the wood type (cherry vs hickory) would impact fuel efficiency results?

[urbangriller]

Hey Chris, good points listed.

Im curious do you think the brand of pellets or the wood type (cherry vs hickory) would impact fuel efficiency results?

Yes, some pellets have a lower BTU value, that is, they produce less heat when they burn, so more are burnt to maintain the heat. That said, I'd be suprised if the difference was even 10% either way, but some testing will give us that answer. I guess one thing to do is to run some heater pellets as a control, they are made for Heat production and so the BTU is a known.

Some BBQ pellets guarantee the BTU, others don't. I guess is you were burning a lot of pellets either from BBQing every day and twice on sundays, or having an BBQ that consumes a lot of fuel, the BTU becomes more important as would the cost of the pellets.

Cheers
Chris

[Dave]

I don’t understand the criticism of the three hour Pellet Consumption test when I confirmed the validity of the results with a second test of 6 hour duration. You can see the results of those tests a bit further down this post.

3 or even 6 hours is not long enough, its like testing fuel consumption in a car & only driving it for 30 minutes. You will get results, sure, but they just wont be accurate.

But I have to say that if your Pellet Grill is having temperature swings as Dave suggests, a blanket won’t fix that: your controller is not working properly or the unit has a mechanical problem.

- disagree on this point too Chris, Pellet Cookers with thinner steel bodies are susceptible to temperature swings if the outside air temp drops or a cold breeze blows through - this is from my personal experience using them.

Start-up is the time a Pellet Grill takes to get to stable temperature; it overshoots then takes time to get down to the set temperature, that’s still start-up!

- maybe with the brands that you sell, but not with ours. Mine gets to the set temperature, say 225F, goes into maintenance mode & stays there

The common misconception is that Pellet Grills are way more expensive to run, they are not: and Pellet Consumption testing confirms that.

- I agree on this one.

Cheers, Dave

[edgy]

3 or even 6 hours is not long enough, its like testing fuel consumption in a car & only driving it for 30 minutes. You will get results, sure, but they just wont be accurate.

It isn't long enough... in saying that, you may want to log other variables such as ambient, humidity and wind.

[urbangriller]

Start-up is the time a Pellet Grill takes to get to stable temperature; it overshoots then takes time to get down to the set temperature, that’s still start-up!

- maybe with the brands that you sell, but not with ours. Mine gets to the set temperature, say 225F, goes into maintenance mode & stays there

Cheers, Dave

Actually Dave, the GMG does not overshoot it's set temperature....if you are paying attention, this is me responding to Jester's statement.

[urbangriller]

It isn't long enough... in saying that, you may want to log other variables such as ambient, humidity and wind.

Have a look at the spreadsheet I use....that's exactly what I do.

You can see in the test above, the ambient conditions are noted, in fact you can see the second test recorrds the ambient as significantly colder and raining as well, and it shows a 3 gram per hour increase in pellet use......presumably as a result of the lower ambient temperature.

Chris

[Dave]

3 or even 6 hours is not long enough, its like testing fuel consumption in a car & only driving it for 30 minutes. You will get results, sure, but they just wont be accurate.

It isn't long enough... in saying that, you may want to log other variables such as ambient, humidity and wind.

100% mate

[edgy]

It isn't long enough... in saying that, you may want to log other variables such as ambient, humidity and wind.

Have a look at the spreadsheet I use....that's exactly what I do.

You can see in the test above, the ambient conditions are noted, in fact you can see the second test recorrds the ambient as significantly colder and raining as well, and it shows a 3 gram per hour increase in pellet use......presumably as a result of the lower ambient temperature.

Chris

Sorry, I worded that poorly... I meant, map those weather data points agains the time value. IF there are any variables you will be able to narrow down what the drivers are that way.

[urbangriller]

I don’t understand the criticism of the three hour Pellet Consumption test when I confirmed the validity of the results with a second test of 6 hour duration. You can see the results of those tests a bit further down this post.

3 or even 6 hours is not long enough, its like testing fuel consumption in a car & only driving it for 30 minutes. You will get results, sure, but they just wont be accurate.

Cheers, Dave

So your flash ute records a significantly different fuel consumption from hour to hour driving in the same conditions?....You'd better take it back to the dealer, there is something wrong with it!

Same goes for a BBQ, if the consumption varies significantly running at temperature in hour 18 compared to hour 3 or 6 then you need to find out why, coz there is something causing that to happen!

Humour us Dave, do the 3 hour test and the 6 hour test @ 200F and post the results, then tell me it's not enough. We'd love to see the results!



Chris

[Commander Cody]

hey................you remember my ham cook-out last week..??..

because the ambient only reached single digits to 7C..........

..............for the 1st time ever i ran out of pellets

i ran it on smoke ( P3 ) for 3 hrs and only maxed at 110f

whacked it on 225f for duration...............

and the wonderful T machine stayed true to temp. but, in doing so had to keep the pellets up to the hot box a lot more.

usually a cook out on 225f would give me 2 or 3 sessions @ 6+ hours each, so in reckoning of that............i would say the T machine had to use 3 times the pellets.

so.................i would think that you would have to create a micro climate to control temps and wind conditions to get a trueish read of the useage

just to muddy the waters a little more.....

have fun fellow freaks.................

kevin

[urbangriller]

It isn't long enough... in saying that, you may want to log other variables such as ambient, humidity and wind.

Have a look at the spreadsheet I use....that's exactly what I do.

You can see in the test above, the ambient conditions are noted, in fact you can see the second test recorrds the ambient as significantly colder and raining as well, and it shows a 3 gram per hour increase in pellet use......presumably as a result of the lower ambient temperature.

Chris

Sorry, I worded that poorly... I meant, map those weather data points agains the time value. IF there are any variables you will be able to narrow down what the drivers are that way.

You'd need some way of measuring the pellet consumption on the way through to do that, the only way to do that would be to put the BBQ on a set of highly sensitive scales so you can see pellet usage at something like 15 minute intervals by looking at the difference in overall weight.

Not sure about your backyard, but mine does not have a set of industrial digital scales in it, nor are we looking for Lab results here, just something the average backyarder can compare to.


Chris

[edgy]

You'd need some way of measuring the pellet consumption on the way through to do that, the only way to do that would be to put the BBQ on a set of highly sensitive scales so you can see pellet usage at something like 15 minute intervals by looking at the difference in overall weight.

Not sure about your backyard, but mine does not have a set of industrial digital scales in it, nor are we looking for Lab results here, just something the average backyarder can compare to.
Chris

Good point Chris, you would need that additional input value

I do have industrial platform scale (digital) that will hold up 15000 kg/20g slope....but no they are not at my house.

So your flash ute records a significantly different fuel consumption from hour to hour driving in the same conditions?....You'd better take it back to the dealer, there is something wrong with it!

Same goes for a BBQ, if the consumption varies significantly running at temperature in hour 18 compared to hour 3 or 6 then you need to find out why, coz there is something causing that to happen!

Humour us Dave, do the 3 hour test and the 6 hour test @ 200F and post the results, then tell me it's not enough. We'd love to see the results!


Chris

Crass, that would be assuming that there was a stretch of road that allowed you to drive for hours on end with zero difference in climate conditions or terrain/hills/slopes etc In the real world you can maintain the same speed even with cruise control activated and those variables will come in to play... its much the same as the pellet grill... in a car to maintain the speed you are definitely going to see difference in throttle position, injector duty cycle and air speed etc.

I believe the point in question is that if you are looking for a direct correlation between temp/consumption and climate factors you need to measure them all to quantify it.



And at the end of the day we will just revert to an average figure anyway

[urbangriller]

And at the end of the day we will just revert to an average figure anyway

Dead right, it's just a Backyard figure we are looking for anyway! Something the average bloke can use as a guide.

So your flash ute records a significantly different fuel consumption from hour to hour driving in the same conditions?....You'd better take it back to the dealer, there is something wrong with it!

Same goes for a BBQ, if the consumption varies significantly running at temperature in hour 18 compared to hour 3 or 6 then you need to find out why, coz there is something causing that to happen!

Humour us Dave, do the 3 hour test and the 6 hour test @ 200F and post the results, then tell me it's not enough. We'd love to see the results!

Chris

Crass, that would be assuming that there was a stretch of road that allowed you to drive for hours on end with zero difference in climate conditions or terrain/hills/slopes etc In the real world you can maintain the same speed even with cruise control activated and those variables will come in to play... its much the same as the pellet grill... in a car to maintain the speed you are definitely going to see difference in throttle position, injector duty cycle and air speed etc.

I believe the point in question is that if you are looking for a direct correlation between temp/consumption and climate factors you need to measure them all to quantify it.

Dead right, and yes I'm using an extreme example, only the manufacturers have that kind of facility, but the fact is, if your car was showing a 20% (say) variance in fuel consumption from hour to hour under similar conditions, you'd be right to be waiting by the dealers door the next morning before they open.

We are talking backyards here, so simple tests are the go.

If anyone thinks their BBQ is producing significantly different results from hour to hour, then they should investigate that further.

I did the three hour test then confirmed the results with another test of twice the duration, I have no reason to suspect that the GMG's consumption in the hours beyond the 6th hour would be that different as to significantly alter the results.

If Dave comes back with results that show a significant difference between his 18hour full bag test in his Yoder 480 and the 3 and 6 hour tests, then I’ll run an 18 hour test on the GMG to see if it also behaves (or should I say misbehaves) like that.

Cheers
Chris

[chriso]

Is this getting too complicated? Like Chris says, it's to provide the average buyer (like me) with an average figure for average use.

There's no point getting hung up on hourly usage and other fine details if the tests are done by different people in different environments and different conditions.