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Electric Vs. Gas
dougabbot
Hi Everyone,

I've been poking around this site for quite a while, but I'm feeling kind of stuck.

I'll give a bit of back ground, the question will come a bit later; so if you want skip to the end.

I'm a special ed teacher in a very small, remote town in British Columbia Canada. As part of my class, some of my students have decided to start roasting coffee, and sell it to teachers before school and at lunch using a siphon and a roaster they built out of lab equipment. The process was very successful and they started selling bags of coffee around town with some of the stores and shops interested in carrying it.

When we started up this year, we decided there were some major flaws in the last design. We looked to the forum and started designing a new roaster and have been building it in shop class. We've been putting off the heat source for a while because it's a little out of our current know how. We have a tc4a board, with a variety of relays and a thermometer probe but we don't know exactly what to do with it. The kids in the computer class seem confident that they can get the board to talk to roast logger and work on that end, but we're struggling with what kind of hardware we need on the roaster end, and how to get the board to talk to the hardware. From what I can tell gas is the preferred method, but electric seems so much easier.

I guess what I'm wondering is; is gas worth the extra hassle? If yes we will give it a go. What kind of solenoid valve will we need and how do we program it? I've seen mention of having a lower flame that is on for the duration of the roast with a hotter flame that flicks on and off during the roast to maintain temperature, but again we are a bit perplexed to how this all works. Welding, machining, roasting and brewing are our strong points... the gas heating seems a bit over our heads at the moment.

Thank you to anyone who can help make this make more sense to us!
I included some pictures of the roaster so far as well as the siphon. It's 11" by 11" stainless with aluminum housing and cyclone.
dougabbot attached the following images:
830orig.jpg 774orig.jpg 241_orig.jpg 203orig.jpg 171orig.jpg

Edited by JackH on 10/03/2015 3:46 PM
 
turtle
welcome to HRO Welcome

Your images did not get in your post. Images would be very helpful in determining what kind of room you have to work with in your burner chamber (am assuming you have a drum roaster with a burner chamber).

I had the same choice when I rebuilt a non-operational SF-1 roaster. Originally it was electric but there was not enough left to tell what needed to be done so I had to start from zero, designing then constructing the controls for the electric burners. At one point I was close to chucking it in and going gas as it was much simpler.

that said you can go through the post that contains the trials and tribulations of my rebuild to get an idea of what was involved getting enough electric heat and how to control it.

http://forum.home...ad_id=4336

I've been using the roaster as an electric for the better part of this year and I have been very satisfied and VERY glad I stuck it out and got the electric sorted and working as I wanted it to work

.
Mick - "Drinking in life one cup at a time"
"I'd rather be roasting coffee"

Roaster 1: San Franciscan SF-1
Roaster 2: Hottop B-2K+
Roaster 3: 2 kilo Chinese drum
Grinders: Mazzer Major - Forte BG (x3)
Pour over: Hario - Bee House - Chemex - Kalita - Bodum
Drip: Bunn CWTF15-1 & CW15-TC (commercials)
Espresso: Pasquini Livia 90 auto
Vacuum: Cona - Bodum
Press: Frieling - Bodum Colombia
 
dougabbot
Thanks for the quick reply! I'll read through the post right now and try to upload the images. We were thinking of parting out an old stove and bending the elements around the drum.
 
dougabbot
For whatever reason I'm having trouble uploading the pictures. I'll just add the link to the blog. http://1-eleven.w...y.com/blog
Edited by JackH on 10/03/2015 3:27 PM
 
JackH
Hi Doug and welcome!

I added some of your photos from the blog to your first post.

To post a photo the file size must be 268KB or less. The filename should not have any spaces in it.
To get the correct size you will have to edit and re-size your photo.

Here is a link with instructions:

http://forum.home...?cat_id=16

It looks like a nice roaster....Congratulations to your class.
I go with electric since there is no gas on my street.

There are many posts in the drum roaster section on both gas and electric setups.
Edited by JackH on 10/03/2015 3:49 PM
---Jack

KKTO Roaster.
 
dougabbot
Thanks Jack, I appreciate that. We're hoping to do around 8-10 lbs in the roaster, you don't think that's too much for electric? Most of the electric builds I've seen on here have been more of the 1-3 range?
 
oldgearhead
In general electric roasters need 1000 watts/pound.
So 8 pounds would require 8 KW and room to enclose it.
Insulated drum? Probably 6-7 KW..or about 40 amps at 200V..
Edited by oldgearhead on 10/03/2015 6:45 PM
No oil on my beans...
 
turtle

Quote

dougabbot wrote:

We're hoping to do around 8-10 lbs in the roaster,


Go gas.....

You "could" design an electric heat plant for that volume but you are talking industrial electric supplies.

Do you think you could talk the maintenance folks into getting that much juice to your roaster's location?

Electric would be a good engineering project for your class. Look into industrial-electric crucible burners if you decide to go this route (love to see the pics and hear the project through from start to finish).

From your photos it looks like you have more than enough room to do anything you want.

NICE PROJECT!!!!!!

.
Mick - "Drinking in life one cup at a time"
"I'd rather be roasting coffee"

Roaster 1: San Franciscan SF-1
Roaster 2: Hottop B-2K+
Roaster 3: 2 kilo Chinese drum
Grinders: Mazzer Major - Forte BG (x3)
Pour over: Hario - Bee House - Chemex - Kalita - Bodum
Drip: Bunn CWTF15-1 & CW15-TC (commercials)
Espresso: Pasquini Livia 90 auto
Vacuum: Cona - Bodum
Press: Frieling - Bodum Colombia
 
billsey
Go with gas, propane or natural gas. If you Google electronic gas valve you'll see lots of options. I'd choose one with either 4-20mA control or 0-24V control. Run a PID to vary the gas based on ET, with set points that gradually rise throughout the roast. Monitor bean temp, environment temp, exhaust temp and perhaps airflow through the drum.

Electric heat just isn't going to work easily with that high of a heat load needed. It's much slower to respond than gas is and takes a lot of juice, which requires heavy wiring...
 
ciel-007
GAS... without any hesitation.
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK´┐ŻNIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
dougabbot
OK, so looking up valves and getting confused. I've read some other forums that have led me to ebay as a cheaper place to pick up a valve that will work. I'm looking for something that would work for a set up where I have a constant low flame and a higher flame that switches on and off controlled by the TC4a as described in

http://forum.home...rowstart=0

Will these valves work?
http://www.ebay.c...4ae619a126

http://www.ebay.c...417e8e6f3b

This is going to sound incredibly stupid... but what difference does the voltage make? I saw reference to people using 12 volt valves, and these are 24, will it still work with my roaster? Does it need to be the H version?

A million apologies for my ignorance. This forum has been essential to helping us build this and I really appreciate everything!
Edited by JackH on 10/08/2015 3:39 PM
 
ginny
hi, why not give us some information on your school and perhaps some comments from your students, while I realize they cannot be photographed our members would love to hear/see their comments about their work and their project.


ginny


rockon
 
dougabbot
Hi Ginny, That's a great idea. The website for the class is 1-eleven.weebly.com Everything except the blog is made entirely by the students. It also has a map for where exactly we are located. Our school website is:

http://northislan...blogs.org/

A bit of background on the school and project...

Our school is very small. We have 308 students from grade 8-12 and we pull from six different rural communities with students traveling by bus and boat from up to an hour away each day. We are 2 hours from the closest Wal Mart or town with a population of 2000. As many small towns around North America, we have been hit hard by the current economic situation. Forestry and fishing has slowed down, and most of the mines and mills are closed. Many of our students come from struggling families and it is considered an area of high need.

It is also a beautiful area with a booming tourism sector primarily in the summer, with a plethora of resident Orcas, tons of humpbacks, salmon and halibut fishing as well as hunting, surfing sailing kayaking ect. Despite some of the challenges of this area, it truly is paradise.

The coffee thing started in January of last year. I teach special education and one of my students wanted an extra block with me. I couldn't justify it in his schedule so him and I worked with the principal to develop an independent studies block. This student had been wanting to work with me to build a coffee siphon for the science fair, and so I posed the challenge to him to create a 2L coffee siphon, build a coffee roaster, and turn his science fair project into a business. He accepted the challenge and got straight to work.

His business took off and became very popular around the community. It got to the point where we couldn't make enough coffee to keep up to the demand. His roaster was very simple and quite inefficient however it was great for getting us up and running. More students became interested in his business and his independent studies block became a block of Entrepreneurial Studies and now includes 12 special education students.

With the money the students have made we have bought an Expobar Office Pulsar and a Rancillio Rocky to teach them barista skills, they have been balancing books, making sales contacts, advertising, roasting, learning about the areas the coffees come from and the list goes on. Many of these students are ones who have felt that school doesn't provide much for them, and have gone from at risk of dropping out, to feeling connected to the school. They are learning real life math, social studies, english, and business skills that will be beneficial to them throughout their entire lives. I with I could go into more detail about some of these stories as the way this program has influenced some of their lives is truly amazing, but of course with confidentiality I can't.

I'll try to get some quotes from some of the kids and post them up here or on the website I think that's a fantastic idea. If anyone ever wants to visit us up here on the North Island, hopefully we can offer you some amazing coffee. We certainly have a passion for it up here. I'd love to show off what my students have created as I think it really is amazing, and as they are building this new roaster I am amazed more and more every day. Some days it's hard to imagine they are only 14-18, and others it's all too easy, but it's really neat to see how coffee and business can have such a positive impact.

Thank you so much for all of the help this forum has been. We were originally going to purchase a new roaster, and when one of my students started researching these forum threads he said "screw it, I can build that." So thank you everyone for sharing all of your builds this really is an amazing community.
Edited by JackH on 10/09/2015 3:36 AM
 
billsey

Quote

dougabbot wrote:

OK, so looking up valves and getting confused. I've read some other forums that have led me to ebay as a cheaper place to pick up a valve that will work. I'm looking for something that would work for a set up where I have a constant low flame and a higher flame that switches on and off controlled by the TC4a as described in

http://forum.home...rowstart=0

Will these valves work?
http://www.ebay.c...4ae619a126

http://www.ebay.c...417e8e6f3b

This is going to sound incredibly stupid... but what difference does the voltage make? I saw reference to people using 12 volt valves, and these are 24, will it still work with my roaster? Does it need to be the H version?

A million apologies for my ignorance. This forum has been essential to helping us build this and I really appreciate everything!


I didn't read too much, but both of those look like electronic on-off valves, not proportional control valves. Look at their EVP line, which open proportionately to the voltage, current or pulse width provided. With an on-off valve you can't control the flame except to turn it ... on or off.

Clippard Valves Overview
 
dougabbot
We were thinking about having an on off valve. The idea was to have one burner that is always on, but a relatively low flame, and one burner beside it that has a higher flame which would switch on and off during the roast. The low burner would act as a pilot light for the high burner as well as help reduce temperature fluctuation from the other burner flicking on and off.
Edited by JackH on 10/09/2015 3:35 AM
 
oldgearhead
If your burner is sized correctly and the ambient temperatures don't swing too wildly a Hi-LO dual burner should work fine, be less costly, and simpler than proportional. Many farm grain dryers run Hi-Lo burners..
But, it must heat the drum uniformly.
No oil on my beans...
 
TheoBro
I don't know if this will be of value, but I've been casually looking through here for possible items to use in a burner component:

https://www.fmpon...ecomm/Shop

One must monkey a bit with navigating the website but there is a lot buried in there.
Edited by JackH on 10/10/2015 3:43 AM
 
allenb

Quote

This is going to sound incredibly stupid... but what difference does the voltage make? I saw reference to people using 12 volt valves, and these are 24, will it still work with my roaster? Does it need to be the H version?


The stated voltage requirement (12 or 24) will be the voltage your driver circuit will need to produce for proper operation of the valve.

The "H" suffix after the voltage number is the orifice diameter. No letter in this space is .25", H is .060". The "M" designation with the valve you linked to is manifold mount so if you decide on this valve you'll need to order a manifold from Clippard.

Whether an .060 valve orifice will be sufficient for your BTU needs will depend on what gas pressure you'll be sending the valve. If you'll be using high pressure propane (over 1/2 psi and probably need around 2 to 5 psi), then you'll be fine with this orifice but if you'll be using natural gas you'll most likely need a much larger orifice.

EDIT:
I mistakenly wrote that with no letter in the space where the H suffix is located means the valve has a .25" orifice but is actually .025" which is obviously much smaller than the valve with an H which has .060" orifice. So, .060 looks to be the maximum diameter available with the ET valve.

Allen
Edited by allenb on 10/11/2015 9:51 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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