Even with a filter, my kitchen hood fan got clogged

I have a kitchen hood installed in my garage and the Bullet normally sits under it. I have 2 MERV11 filters to capture any shmutz, but they have not been doing a good job.

I pulled the hood and took it apart for cleaning and this is what I found: (the outside of the fan blades)

After using a paint brush to knock back some of the shmutz so you can see that the fan has blades:

The inside of the fan blades:

After a little brush to see the fan blades:

I ended up taking the fan out and deep cleaning it with Cafiza. when I got done, the fan was very clean and not sticky.

This is the exhaust vent:

After cleaning:

I only roast a few Kilos a month and rarely go into the second crack.

I had filters in place and still got all of this buildup.

I am in the process of building a new filtration system and will bypass the hood.

I will post that when it is ready.

Bill, have you tried the elecrostatic furnace filters. I don’t know if they would help but the static charge may help collect more smoke particles. If you are using the electrostatic they become less efficient as they get dirty & less efficient at higher air flows.

How long has it been since you last looked at your hood or cleaned it?

Were both exhausts venting through the hood? Did you have some kind of tubing or just let the Bullet sit under it?

I have an inline fan that pulls smoke from the bullet and goes through a tube that is placed under the hood. Even the hood filters never get dirty. That’s why I’m asking.

I didn’t try electrostatic filters. I am aware of them, but didn’t want to add more stuff to the filtration side of this equation.

Thanks for the suggestion.

There was a person on this forum that told me that he had designed and built an electrostatic filter mechanism that removed 90+% of all particulates and smoke, and he was going to develop a product. I don’t know whant happened to that endevour.

I am working on another solution that will remove all of the chaff and reduce the smoke and discharge it out a vent. I have been running tests and have most everything worked out. I just had to change some of the tubing from PVC to steel due to heat issues and the PVC.

If it all works, I shouldn’t have to worry about chaff buildup and affecting the air flow of the fan (F1-F9). Therefore my recipes should not need adjustment due to chaff clogging the chaff basket filter. I am expecting to be able to roast 20 or more kilos of beans before emptying the new chaff filter. This new system will be a cart mount. And maybe eventually use a kitchen island cart purchased from Amazon.
It will have a touch screen tablet for the RoasTime computer.

I bought a 3d printer and have been printing a lot of my fittings.

I want a clean looking installation.

I used to have a HotTop and the hood worked fine for it. But, the HotTop has a smoke reduction function built into it so that it burns off most of the smoke.

The Bullet sat on a lazy Susan under the hood and I had sides and a front cardboard barrier. The bottom 2 or 3 inches was open so that air would be drawn up and around the bullet and then be drawn outside due to the fan in the hood. I didn’t have any special hoses to gather or direct the smoke. I didn’t end up with much smoke in the garage.

After having the Bullet for a year, I found that the hood had gotten totally clogged. I ended up just replacing the hood. That was 2 years ago. after that I ended up upgrading the filters to MERV11.

This new system that I am working on will eliminate the need for a hood or filters.

Here is an early photo of how I had it set up but I didn’t have the front carboard barrier in place with the air entrance at the bottom when I took the photo.
This only had 1 MERV8 filter. I changed that to 2 MERV11 filters.

1 Like

I mostly roast naturals.

My main reason for this thread was to show people that under some conditions, you need good filtration.

1 Like

It’s a good point and it’s very useful. I’m watching the game now and don’t have photos, but the shmutz usually ends up on the inline fan and the vent hose attached to the fan that’s running to the hood. I clean those after each roasting session. I’m surely around 10 feet from the hood with the roaster. I’m in a large space so I get almost zero smoke. The air purifier kind of turns on for a minute or two toward the end of the roast.

1 Like

Wow. I have run in excess of 300 kg of coffee thru my Bullet in the last 2+ years. It is not running thru a filter. I have flexible metal ducting with a Cloudline S4 fan in line. I have taken the fan apart once to clean. There is a coating of brown “shmutz” on the inside of the duct work. It all exhausts from my basement thru a metal dryer vent I installed that is dedicated to the roaster exhaust.

I thought about adding filters to save the S4 fan, but then I thought I might spend as much in replacing filters as it cost to just replace the fan every couple of years.

This is interesting.

Maybe this is a case of: “lack of velocity” where my bullet is really relying on passive extraction of fumes and particulates and the air is moving so slowly that the particulates have more time to stick to the fan and housing. Once they start sticking, it is easier for more particles to stick to the first stickees.

Edit: I agree with your maybe having to replace the fan vs the cost of the filters.

I ran across this article in case your interested.
In my vent I put my duct fan at the end of my vent. I was using a window fan at my house & didn’t think it was working well. I discovered backwash where the air is pulled back into the fan & recycled thus reducing the fans flow. I had to seal around the fan to prevent that. My thinking of putting the fan at the end that on the suction side the air would swirl against the sides & bends in the duct & produce some back pressure & thus reduce flow where on the end it would pull the air & reduce back pressure. Also it reduces buildup in the fan.

Very interesting

@billc do you know how many CFM that hood range vent you’re using is? Wondering if that may be a factor.

The CFMs aren’t listed anywhere for that hood. they just say that there are 3 speeds. Selecting this hood was primarily a size consideration. It was also orignally for my Behmor, then the HotTop. neither one of them produced much smoke.

I’m sure it was a factor.