Hello everyone, 

   This format is different from that I am used to... I am not familiar with the wall feature, so I first post it there instead of adding a discussion (which is probably why I did not get a reply) sorry about that, me bad! 

Thank you for accepting me in your group!

   My work is about super-insulating and air tightening homes very well. So far all the jobs I have done had electric stoves with a decent range hood. I am working with a couple regarding their project, and they have a gas stove that they want to keep and their range hood is just not doing anything.  So they are willing to replace their range hood that has the power and exhaust outside. There is not a cabinet on top of the stove, which is great because we can install the range hood to the appropriate height, which is one of my questions, what is the optimal height?  What about sizing the hood?  Should the size be the same as the stove bellow? 

   I was also wondering if the shape is important or not. It seems that older hoods used to be open to help direct the byproducts to the fan, but as I search online for hoods, they are all flat at the bottom... is that an issue? 

One last question... is there such thing as a hood with a sensor so it will go on when it senses cooking?  All my bathroom exhaust I will always have a humidity sensor, this way the fan goes on as soon as detects humidity and stays on well after the shower is over, removing all excess humidity. Having a sensor eliminates the human error of not using the device. 

Thank you so much for reading my post, I am looking forward to your replies!

Luis

Views: 153

Replies to This Discussion

Hi Luis, Thanks for posting on Home Energy Pros! You're welcome to post in both this group and the general forum. Cheers! Diane, HEP Moderator

For residential homes there are not a lot of sensing options out there that have tested and been certified.   

There are several issues with kitchen cooking - and they apply to all stoves not just gas!

1) capture range of the hood.  Some hoods do a poor job of capturing the rising steam and by products from the cooking process.  For a better explanation of the capture range,  look at the LBNL paper found at:

https://homes.lbl.gov/sites/all/files/lbnl-5545e.pdf ,  It written by William Delp and Brett SInger.  Both have published more recent updates on their research and they've been looking at sensors.  You can find more of their published papers by looking for the Bio's of the two authors at the LBNL site and reading all night long..... lots of good reading.

2)  If you find a hood with a good capture range,  place it correctly,  you are also going to want to ensure that you have replacement air for the stove coming into the kitchen by the stove.  Again,  this doesn't mater if it is an electric or gas,  cooking produces grease, water vapor, heat... and lots of VOC's.   It's true that NG produces CO2 and CO as well as NOx,  but those other byproducts from even an electric stove can still cause problems.    My particulate counters that are in the dining room,  jump quickly to about 7000,  when I'm simply microwaving a bag of popcorn.  Cooking can generate a lot of interesting by products.

If the exhaust fan is 250CFM,  expect to allow 250 CFM of air coming into the kitchen.  Some higher end range hoods can signal a damper that allows fresh air to be injected down by the cabinet floors.

3) Activated carbon filters - are essentially grease filters.   Long term they don't get changed as often as they should,  the manufacturers sometimes stop making them,  they DO NOT capture all the bad stuff... trying to solve a problem by using big activated filters and venting back into the kitchen isn't a great idea.

4) UV filters to kill the smells, bad stuff... generally do not work.  Worse yet is if they UV light is where a person can see the light or its reflection -- you can damage your eyes.  The corneas can be damaged by UV,  and it is possible to get melanoma on the retina...  really bad idea to try to fix a ventilation by using UV lights which may not be operating at the correct wavelength, power levels and have the dwell time on the gases to be effective.

5) problems with sensors,   too much moisture can clobber the sensors making them in effective.  Too much grease on the sensors will cause them to not read correctly, few consumers would understand how to recalibrate sensors.   Particulate sensors work... but the better ones (laser based) age and need to be replaced.  VOC sensors are available but haven't yet had the history of use to demonstrate that they might fail and not produce the desired results.

I'm and engineer and my solution is to use multiple sensors and detect failures... however such solutions add to the product cost -- and -- many consumers worry about a $5 add on cost.  Manufacturers are sensitive to what the consumers are willing to spend.

When I use my stove (NG), it is always on at the highest speed.  I cook primarily on the back burners so the capture range is most effective... I have a note taped on the hood that says "TURN ME ON,  OPEN WINDOW".

In my case,  even though I work with sensors and could create  (DIY) a system with sensors to activate the hood and a draft damper,  I also recognize that these are not yet mainstream items... which means when I eventually decide to sell the house - they will not be an asset but a handicap.

As noted there are vendors, researchers,  and manufacturers working to really under stand the capture range and to develop sensors that will hold up over time.   I doubt that you'd find information about them at a big box store like Lowes or Homedepot.  The manufacturers may provide some information on their products.

I would suggest an internet search for "kitchen hoods with sensors"  and look for sensors that are designed and will be supported for the life of the kitchen remodel.

I did attend presentation about two years ago in Chicago on range capture hood sensors research that was underway... led by group out of the NE,  Brett Singer, PhD of LBNL I believe had been working with the group to help understand some of the problems... and I saw range capture studies being done at GTI in Des Plaines IL. 

Luis - 


Check out this link for some good information on vented range hoods:

http://rocis.org/kitchen-range-hoods 

-Rob

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