air

debbiej

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Mar 22, 2010
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I would really appreciate some advice on air flow around the drum and cooler. my roaster is an older YM 2. it has an awkwardly positioned motor that turns the squirrel cage blower. the fan and motor fit tightly inside the chambers that air moves through. the motor is an import motor, and I've not checked but have been told there isn't a replacement motor that will fit.

If we mount a squirrel fan outside the roaster, say somewhere in the exhaust, blowing up to boost this fan is there a danger of over pulling air? I don't mean a huge fan, but I could see the wrong fan affecting the amount of heat to the drum.
 

coffeejoes

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Sep 6, 2007
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I have a newer YM-2 with a squirrel cage fan. If I do not keep the fan clean my air movement as measured by a handheld instrument at the roaster exhaust will drop by 50%. The darker the roast the quicker the reduction of air flow. I need to scrape all the blades with a brush or flat screwdriver. Every three cleaning I remove the motor and soak the cage in purocafe. I would also check your exhaust stack. I keep this as clean as possible with running a wire brush from the bottom to the top once a month. The rest of the roaster I also clean once a month. I hope this helps.
 
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debbiej

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Mar 22, 2010
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it does help, thank you! It is interesting to note that the air is reduced by 50% by a dirty fan. because my roaster is older, the venting is square, about 2.5-3" square and has some unreachable turns. you can slide the drum over by removing 4 bolts, and reach the venting, which we did. we also removed the cooling tray and followed the path the exhaust takes looking for clogs. I too have to scrape the fan blades between roasts. I've bent a skewer and a hacksaw blade to scrape without removing the motor and fan because it is very difficult. the next roaster I get will be easier to clean!

the winds are very strong in the spring here, and I've extended the stack. also, my husband ran heavier electrical wire to the roasting shed, thinking there could be a resistance problem there.

is your device that measures output a separate tool?
 

coffeejoes

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Sep 6, 2007
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My technique is rather simple. At the beginning of each roasting session, I pull the 4" exhaust from the exhaust port on the roaster. I then turn on the roaster absent the burner and then place the air measurement device(I am sorry but I have forgotten the name) up to the exhaust port to measure the wind speed. This device measures speed not cubic feet per minute. Perhaps someone out in cyperspace can comment if there is a formula to convert to cfm. If this is possible you could then compare to Ambex's rating for the fan. In practice, I had found that if the wind speed drops more than 15% my results change for the worse. I think this is a very rough measurement gauge since there are many factors that may influence the reading of the wind speed. If you use this method It should establish some cleaning parameters.
 
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debbiej

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Mar 22, 2010
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I've found some gadgets that measure airflow, good to know about.
tonight I went out to clean out and start up the roaster. I don't need a airflow meter to know something is really wrong. that exhaust fan is barely blowing when I put my hand up to it. but the motor sounds the same as ever. I'm hoping there is a screw that holds the fan that has slipped or something equally fixable. otherwise I'll be looking for a supplier of good coffee until later in the month. :(
 
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debbiej

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I thought I'd post a sort of follow up. after all the things we did to the roaster; had the motor checked at a shop, cleaned every part really well, new, longer, better fitting stack, new higher rated regulator, heavier electric cord to motor; it seems to be much better. it could be a combination or just one of the things--don't know. but there is no smoke coming out of the top of the roaster when the hopper door is open, the smoke and chaff is rolling out of the top of the stack freely. the temps and times seem right on. all that remains is to taste the coffee......

and the coffee is good! :)
 
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