What are 'Filterless’ Kitchen Chimneys?

[kiran6680]

I've run into an information blackhole about kitchen chimney filters especially "filterless". Our old thread
https://techenclave.com/threads/looking-for-a-chimney-for-a-usual-indian-kitchen.209275/ was nice, but most links are dead - especially those that are supposed to include information about "filterless".

My friend is looking to find the perfect chimney for the kitchen, but these new “filterless” models are as confusing. Every brand, review, and YouTube video basically says, “No filter! Self-cleaning! Just empty the box!” But many questions are unanswered:

If there’s no filter, how on earth does the oil not end up clogging the pipe? I don't need my chimney turning into a party place for bugs.

And what magical tech is shoving all that oil into the collection box? A heat coil alone isn’t going to cut it.

If the only difference is the lack of a filter, why aren’t these filterless chimneys cheaper? Something fishy is going on.

When companies mislead, it’s usually not in our favour. Does anyone have the inside scoop? Long term review of filterless? By the way, the fancy BLDC motor is only available in the filterless models, so I’m kinda stuck. Any help?

 

[smaratha]

Yes, the landscape is quite confusing. I can share my recent experience after buying a house and completely redoing the kitchen.

These are the primary factors which should influence your buying decision. I will also share the some installation guidelines for your hood to be effective.

1. SIZE: Your hob or stove size. If your Hob or stove is 2-3 burner you can go with the readily available 60cm segment. If you have a kitchen Hob then you should go for 90cm segment for the effectiveness. Its simple laws of physics which I have seen people commonly ignore and then blame the chimney for not being effective.
2. SUCTION POWER/NOISE LEVELS: Your cooking style and oil usage. In a typical north indian household where paranthas are daily cooked on high heat and lot of kadai is used, you need at least 1200 CFM suction power to suck the oil out. Just remember more suction also translates to more noise. It depends on how much you want to balance the suction and noise levels. On the noise front, I have seen people skimp out on installation charges by using the manufacture supplied exhaust pipes which create more noise as they work as noise amplifiers of the kitchen motor and air flow. If you have the luxury of creating the installation from scratch prefer a 6" PVC pipe for exhaust ducting duty. These PVC pipes are a one time investment vs periodic change of the thin aluminum sheet based pipe which is also prone to rodent attack and flimsyly prone to tearing whenever you are cleaning the kitchen. Your design should also minimize bends on the way to your kitchen outlet. More the bends, the more deposit of oil and more resistance for the air to go through cleanly. Also a rule of thumb is to never have a bend directly above chimney which would increase the noise by a factor of ~25% approximately. One of the practical problems with noise which one does not realize is the fact that you have to communicate with the person cooking a lot of times and the white noise of chimney which may not be of too much problem for the person cooking, effectively disables the communication request of "Ek aur parantha dena!" Typically 60db noise levels are par for the course in most brands.
3. FILTER: (I know!) IMHO the chimney has a very western origin and therefore minimizing the labor cost and effort of cleaning the parts was the primary design goal of Baffle filters which was introduced and patented? by FABER. The first gen chimneys had cassette filters (basically a zali) which was a mesh of metal that required frequent cleaning. The true baffle triple layer design has two "semi circular" pipes with a sandwich layer of flat type. This type of filter when used in a chimney enhances the overall life of chimney as claimed by Faber. They also provide a 10+ years warranty in most models which use this filter as it prevents motor and parts clogging by oil most effective. The other brand baffle filters are mostly see through between the pipes if you happen to view them at an angle in person, while the Faber one is opaque. These baffles are usually the oil deposit banks for chimneys which store the non sucked out oil until you clean them. The downside? You have to clean them almost every two months by dipping them in boiling water with a lot of caustic soda high detergents (read Ghadi detergent!) and let them sit for a while and clean with a supplied brush by manufacturer. You will frequently find "auto clean" feature accompanying the double layer baffles by manufacturers as the oil goes to the blower part and gets deposited there which needs to be cleaned periodically. This is where the filterless chimneys come in. They completely do away with any pretense of "filter" and have a very broad open mesh bottom which you can easily remove and clean with a brush if you want to. The auto clean function is a simple heating element around the blower assembly which when started heats up the oil deposits on blower and makes it trickle down the chute and gets deposited in a big tray which sits behind the chimney frame which is at an angle that helps gravity do the work of collecting this residual oil. These big easily removable squareish pipes have a see through window where you can see the oil filling up to the top. Most filterless models therefore (should?) come with a sealed motor assembly and an open blower design to minimize the motor getting any dust and oil deposit to enhance its life. It is basically a BIG exhaust fan in principal. Now the choice of which technology you use is dependent on your ability and willingness to clean the filters for functionality and endurance.
4. BRAND: I would suggest that you look for the service network in your particular location where you would want to avail the service and gather feedback from local folks if you happen to live in a Tier 2/3 city. Most brands have a good coverage in metros and Tier 2 cities but your mileage may vary. Triple layer Baffle is a Faber exclusive technology and therefor forces you to adopt that brand. You can also evaluate the warranty coverage vs cost between brands.
5. DESIGN AND AESTHETICS. Its a personal choice of having a glass front or metal frame in design. Prefer something which is easy to clean and maintain. If you have a space constraint there are fold away models which open and close when you are not using them. These would obviously reduce some effectiveness but have a use case if space is a bigger constraint.
6. INSTALLATION: I would suggest a non brand civil work installation instead of manufacturer one. I only paid the brand guy just to ensure the manufacturer does not create any warranty hassles later.
Design goals are: Durable pipes with sufficient cross section for effective air flow and as few bends as possible for minimal maintenance afterwards. Keep the manufacturer provided guidelines in mind as well as your height and functionally bumping of the primary kitchen user's head and slab height in mind when installing the hood. You STILL need that exhaust in your kitchen! Irrespective of chimney size the exhaust still has a functional duty in most indian kitchens.
7. Online vs Brick and Mortar: I personally found that in 60cm segment there is a lot of competition and therefore the local brand and company store can most of the times match or beat the online prices. In my case the 90 cm segment had a significant cost difference between what the local shops were quoting vs online. Also the 90cm is not stocked by most dealers and you have to get it on order in most brands i happened to enquire on in my locality. There are a lot of hardware specialized markets in metro cities where you can window shop for different brands and prices. In Delhi as an example Rajapuri and Ganesh Nagar in West Delhi. Rohini in North etc. You will also hear misleading comments by local dealers saying that online models are more fragile and made of thinner gauge metal, don't fall for that BS.
8. MOTOR TYPE: BLDC? Typical household use case has a few hours of hood usage and BLDC motors come at a significant cost premium to justify the business case for the economy they bring in electricity consumption. Most manufacturers provide a 5 year warranty on normal motor which to my mind was an ok deal at that time, so I opted for a non BLDC motor.

 

[kiran6680]

Thanks, that's very helpful.

This is where the filterless chimneys come in. They completely do away with any pretense of "filter" and have a very broad open mesh bottom which you can easily remove and clean with a brush if you want to. The auto clean function is a simple heating element around the blower assembly which when started heats up the oil deposits on blower and makes it trickle down the chute and gets deposited in a big tray which sits behind the chimney frame which is at an angle that helps gravity do the work of collecting this residual oil. These big easily removable squareish pipes have a see through window where you can see the oil filling up to the top. Most filterless models therefore (should?) come with a sealed motor assembly and an open blower design to minimize the motor getting any dust and oil deposit to enhance its life. It is basically a BIG exhaust fan in principal. Now the choice of which technology you use is dependent on your ability and willingness to clean the filters for functionality and endurance.

Ok, nicely described, a big exhaust fan. But then lots of oil should get into the pipe over several months? Over a few years, I even expect oil to start dripping out of the outer opening of the pipe. It seems incredible that people are so happy there is no filter, while saying nothing about why filter was present in the first place.


I went to a showroom and saw BLDC motor in action - I don't care much about the efficiency but it was much less noisy for the same air output.

 

[smaratha]

I think you are looking at it from a different perspective. The primary reason for oil based fumes to exit via a vent is to keep your kitchen safe from all the oil and gunk deposits which are likely to form on surface, ceiling and walls eventually if you do not go for a direct hood on the hob or stove. You also want the cooking to be a better experience if all those fumes and tadka oils don't get to your nose and help with all the accompanying hot air leaving the cooking area with the shortest possible path out of the kitchen. I think I missed to ask the question of your primary reason for buying a chimney in the first place?

None of the manufacturers and currently available technology is guaranteed to remove 100% of the cooking residue from your stove/hob. And no 'one' technology or manufacturer promises that outcome with any model.
Your concern of a doomsday scenario where oil is dripping down from outer opening of the pipe is also too pessimistic. Chimneys have been in use for a few decades now. Even at 98% effectiveness over a few years a big chunk of consumers would have had to deal with your visualized situation. I don't think that's the case as consumers would have abandoned the appliance long ago. If your fear is about the ducting pipes being overflowing with oil, you can go with the replaceable thin aluminum ducts which are sometimes bundled by manufacturers as a part of installation. You can discard these and replace with a new one every few years.

With respect to auto clean being a miracle, probably a local sales person has overhyped this and made you suspicious of the technology? Auto clean does not translate to no cleaning, eventually all chimneys would need to be deep cleaned after a few years of installation. This would be true of any air exhaust tool irrespective of location(just cleaned that CM Hyper 212). The only difference that the filter less technology brings is the reduced effort of cleaning the baffles every two months or so. The hood is designed in such a way that the oil is supposed to drip down and get efficiently collected in a large 'bank' of steel block for later removal. If the oil flows down and gets collected where it can be discarded, its a design and not a failure of the appliance.

Again this is a manufacturer provided choice which you as a consumer are free to make. Most manufacturers provide a large array of technology and features which you are free to make an informed choice on.

WRT to BLDC and noise levels, your experience is largely correct. Just be aware of the fact that the demo stores do not have a venting pipe in all cases and the noise that you experience in your installation can be of a different nature and magnitude by the virtue of exhaust fan and ductal resistance. But as i already said above, the BLDC technology was available at a premium of 60% when I was making the purchase and its a consumer's choice to pay that premium for the slightly reduced noise level and some more electrical efficiency, which I did not opt for at that time. Over a few years brush less would be mainstream and premiums can fall for a larger section of consumers to opt for the feature?

 

[sato1986]

Basically all slanting chimneys usually come in filterless tech. The oil collected from the fumes is dripped into the bottom portion of the chimney (the silver line in the bottom of chimney as in pic below)
This specific model is having suction of 2400m3/hr patented by Cata Spain and KIW India. Over past 3+yrs of this model, having sold many units, we have received excellent feedback on suction power of this model.
Please note, the two inlets eventually go into a single outlet of 6inch.

Apart from this, many top clients also design DIY their chimneys by using wood/HDHMR along with metal in-line extraction fans