Freddo

[artman]

On a cool evening in (relatively warm) garage, while roasting I opened the garage door and noticed a drop in bean temp when the cooler air filled the garage. Proof that ambient temp does affect the roast.

It is a very easy to use roaster that gives great results.

Cheers

[Barry O'Speedwagon]

Hi Andy,

I'm not trying to be smart, just trying to understand the roaster better. [EDIT: ....as I'm not sure the Behmor does draw cold air in....]

1/2. I measure exhaust temp (which isn't at all useful actually) but it does shows the exhaust fan only kicks in around 4-5 min (see temp spike in black line in profile). From this I concluded it was a closed system. So I think not much comes out of the exhaust at all. The gradual increase in exhaust temp graph is just the unit itself getting hotter.

There's a cold air intake directly below the exhaust. Just because the exhaust fan is inactive until (approx) the time the afterburners kick in doesn't mean that no exhaust is created. It's just not being blasted out by a fan.

[LeroyC]

Hi Andy,

I'm not trying to be smart, just trying to understand the roaster better. [EDIT: ....as I'm not sure the Behmor does draw cold air in....]

1/2. I measure exhaust temp (which isn't at all useful actually) but it does shows the exhaust fan only kicks in around 4-5 min (see temp spike in black line in profile). From this I concluded it was a closed system. So I think not much comes out of the exhaust at all. The gradual increase in exhaust temp graph is just the unit itself getting hotter.

3. I've never noticed opening the door requiring more force at the end but will check it out next time.

4. If it's a closed system, then room temp will only have a significant difference in the first few minutes. However if it is continually drawing in external air then yes it will make a difference throughout the entire roast. Though if this was the case, I'd expect the exhaust temp (black line) to be the same as the roasting chamber air temp (pink line) as that is where the air is coming from. They are obviously miles apart.

5. The difference would be if Behmor wanted to maintain the same roast times as a closed system, they would need a more powerful heater. That would increase production costs and who wants that.

So I hope you can see why I'm confused. [Edit: ie. My data tells me it's not drawing in external air but you're say it does so just trying to understand if it actually does and if so why?]

[ATTACH=CONFIG]14909[/ATTACH]

Erm, if the exhaust is blowing air out it has to come from somewhere doesn't it? I think you answered your own question when you said there's no vacuum created.

Leroy'stillscratchingmyhead'C

[MrFreddofrog]

Instead of continuing to answer your questions I'll ask some instead...

1: What comes out the exhaust on the back?
2: Where does it come from?
3: Is the door hard to open at the end of a roast due to a 16 minute vacuum?
4: Could the temperature of air in the room make a difference?
5: If so, what difference?

Hi Andy,

I'm not trying to be smart, just trying to understand the roaster better. [EDIT: ....as I'm not sure the Behmor does draw cold air in....]

1/2. I measure exhaust temp (which isn't at all useful actually) but it does shows the exhaust fan only kicks in around 4-5 min (see temp spike in black line in profile). From this I concluded it was a closed system. So I think not much comes out of the exhaust at all. The gradual increase in exhaust temp graph is just the unit itself getting hotter.

3. I've never noticed opening the door requiring more force at the end but will check it out next time.

4. If it's a closed system, then room temp will only have a significant difference in the first few minutes. However if it is continually drawing in external air then yes it will make a difference throughout the entire roast. Though if this was the case, I'd expect the exhaust temp (black line) to be the same as the roasting chamber air temp (pink line) as that is where the air is coming from. They are obviously miles apart.

5. The difference would be if Behmor wanted to maintain the same roast times as a closed system, they would need a more powerful heater. That would increase production costs and who wants that.

So I hope you can see why I'm confused. [Edit: ie. My data tells me it's not drawing in external air but you're say it does so just trying to understand if it actually does and if so why?]

[Andy]

Ok this shows my lack of knowledge about how Behmor functions but if you never ask.....

Why does the Behmor draw cold air into the roasting chamber? Doesn't it just heat the air inside it? To drop temp I assumed it just cycles the heating elements on and off (PWM) though I guess drawing cold air in will make it drop faster.

Instead of continuing to answer your questions I'll ask some instead...

1: What comes out the exhaust on the back?
2: Where does it come from?
3: Is the door hard to open at the end of a roast due to a 16 minute vacuum?
4: Could the temperature of air in the room make a difference?
5: If so, what difference?

All good roasters use heat, airflow and agitation to provide an even roast. The Behmor in principal is not much different to my commercial drum roaster which is also why the taste of the beans out of the Behmor are very close to a commercial roast and usually better than all the other domestic roaster appliances.

This is why it continues to be the home roaster with the most amount of competition wins, it's nearly unfair on the other roasters which cost 2,3 or 4 times as much.

[MrFreddofrog]

Without getting into long discussions about thermal mass and stored residual heat... not all warm-up routines will be the same, even when made easier with a HeatSnob.

Ambient temperature has an effect all through the roast as coffee roasters draw cold air that needs to be heated. If you don't have a baseline for how to deal with the a low ambient temperature for the full roast cycle then pre-heating only changes the first minutes of a roast.

Ok this shows my lack of knowledge about how Behmor functions but if you never ask.....

Why does the Behmor draw cold air into the roasting chamber? Doesn't it just heat the air inside it? To drop temp I assumed it just cycles the heating elements on and off (PWM) though I guess drawing cold air in will make it drop faster.

[Andy]

Without getting into long discussions about thermal mass and stored residual heat... not all warm-up routines will be the same, even when made easier with a HeatSnob.

Ambient temperature has an effect all through the roast as coffee roasters draw cold air that needs to be heated. If you don't have a baseline for how to deal with the a low ambient temperature for the full roast cycle then pre-heating only changes the first minutes of a roast.

[MrFreddofrog]

## Moved the below noise from a useful thread - 22 Jan 2017 ## - Andy


Doesn't preheating remove the ambient temp variable hence making the process more repeatable, assuming you do it to the same temp which is easy with a heatsnob?