Your 1st picture in the article covered several lines of text. Let me know if this is my fault (screen resolution, etc) or just an editing mistake. You mentioned the need to provide replacement air. Please elaborate on proper size, placement, and locations. How do you keep cold outside air from filling your kitchen to replace the exhausted air?

Thank You

Tim, I see 2 major problems with your answer to this lady's question:

1. Range hoods should be sized to the range, not to the kitchen. There is absolutely no need for any residential range to require 1000 CFM. About 150 CFM is adequate.

2. There is no such thing as a passive air inlet that admits 1000 CFM. There isn't even one that admits 150 CFM. If you want to prevent backdrafting, you must open a window.

Tim/Charles; there are problems with both of your approaches to the kitchen exhaust fan:

1. The exhaust should be designed with the intent as a commercial kitchen exhaust system.
2. Although low cfm will exhaust vapors, the real culprit and fire hazard is grease. That is why the velocity should be high. Generally, something in the vicinity of 1,500cfm is ideal, This has the effect of scrubbing the grease off the walls of the duct. Unfortunately, this "air scrubbing" isn't quite enough, but; it helps.
3. As much as possible, the duct should be seamless, preferrably welded so it is watertight at all joints. Remember, build it as if to expect a fire. Also, install it with the same clearances and protection from combustibles as for a red hot wood burning stove going through your walls, floors, roof, etc.
4. Make-up air works well passively if a separate air supply duct introduces the air at the hood-air boundary. This allows the exhaust fan to pull the air into the exhaust stream while minimizing the amount of heating or cooling energy loss...it's more energy efficient.

Hi

My question is I want to install a small range under my window in my basement suite. Do I need to have a exhaust fan and if so can I install one as part of my ceiling which is about 48" above the stove?

tom

hello im working as a hvac designer here in dubai..since i only been 6 months in my company i dont have enough experience..i want to ask how to cumpute the exhaust needed for a kithen and how to compute makeup air needed for residential kitchen

Ok...that's twice. Hit wrong key with a splinted finger in the middle of my mssg and caused both to send and can't retrieve either...I give up.

Maybe in a day or so I'll try again. Sorry for the false start(s) and appologizre to anyone eager to answer if they only had the entire question..basically NEED to use downdraft exaust and need some help/ House is 70yr old sngl story cottage with crawl space and raised deck attached to outside wall. Stove is 4 burner gas. Kitchen dims are approx 10x15 open to 10x12 DR and partially open to 20X25 LR through full wet bar. Can't go straight up or up and out.\]

What's my solution ?? Thanks in advance.

Grey G