What size is the vent pipe? What makeup air system have you explored for the added ventilation requirements?

46" vent and no idea.

The actual pipe may need replacing from top to bottom if it’s not 8”-10”. A 48” range requires a 54” hood, plus the makeup air. Ventilation needs costs about what the range does, or more, if the pipe has to be replaced.

If there is room, then a pair of adjustable elbows can achieve the desired offset. However, the entire system has to be evaluated for the potential need to be upgraded in certain respects as noted above.

I have a 48" 1200 cfm hood above a 48" gas range and it's plenty! No need for anything larger. I added a passive make-up air system for well under $1,000. I just wanted to add this so you don't get scared by the "only this can work" posts...

Agree with @lucky998877, same here.

I have a 48" 1200 cfm hood above a 48" gas range and it's plenty! No need for anything larger. I added a passive make-up air system for well under $1,000. I just wanted to add this so you don't get scared by the "only this can work" posts...

Unless @lucky998877 has instrumentation to measure a large number of VOCs, the actual CFM's of the hood, depressurization levels of the house and has conducted a large number of experiments with different conditions then this is a quite irresponsible statement.

If someone lives in a very leaky house in southern California and their cooking consists of boiling water on an electric range then the above is likely true.

However, someone in a moderately well sealed house in a snow state who enjoys pan frying on a gas range, doesn't enjoy the odors of meals past and is remotely concerned about their and their families health would do well to ignore that poor advice.

Worse, someone who has a naturally vented furnace or water heater in a moderately sealed house and installs a 1200 CFM exhaust hood that causes one of these to backdraft and fill the house with CO (IIRC there are about 200 deaths per year from residential CO poisoning and an estimated 60,000 people per year who suffer permanent injuries from CO poisoning).

Among other issues, the US population has the poorest level of health and lowest expected lifespan of all developed nations. This is primarily due to low physical activity (people in Europe and elsewhere are 5x to 17x as likely to bicycle or walk for transportation) and secondarily to poor diet but poor indoor air quality in the U.S. is also a significant contributor with high levels of CO2 (and NO2, etc.) a key factor. Good ventilation for cooking is important.

Oh Jesus, people must be dying left and right due to not having a monster hood! Not irresponsible, just more like "everyday people" kind of statement. PS. I'm European!

Take a pill. IMO venting is the biggest item for a 48” range and IMO no one needs a 48” range in a home unless you cook for 20+ 3 meals a day. The hood and the MUA are expensive to do right and I don’t care how so and so did his.I run a catering biz from my home and have a 36” 6 burner gas range that handles anything I throw at it plus I do have double wall ovens that are electric I happen to love gas for baking stuff like bread and pizza for sure hence both types of ovens. Everytime you put a bend in a vent system you lower CFM and IMO you need 10” venting no matter what and the more adjustable venting the better for a gas range and get a hood that is more like a commercial hood not with venting running in a cabinet. A 48” range needs a huge kitchen and designed to handle the range.

Craziness over a question about a hood size! Gotta love the internet. FYI, my house is over 60 years old in the South. Air leaks is a common occurrence. No way around it. I am not worried about back drafts or CO poisoning and such. The hood and range manufacturing I am looking at buying recommend the same size. In our city, a makeup air system is only required by code if it's greater than 1200 cfm. The one I want is at 1000.

My original question was whether or not elbow of some type could be used. From research, it appears I can if A) the correct piping is used, and B) no more than than 3 turns and C) right diameters are used, and D) the amount of run between elbows are enough without restricting air flow. Only @kaseki even tried answering the simple question without complicating the issue. :-)

Btw, my range costs anywhere from $9000 to $12000. So, I'll be shocked if running a slightly larger pipe costs anywhere near that.

Thank you all for the feedback though!!

It’s a national building code that requires MUA for any hood over 400CFM. It’s required where you live too. Ignore the negative health effects all you want if you don’t mind risking your family. I hope that you at least have several CO1 detectors in the kitchen and anywhere else that combustion exists in the home. Because it is building code everywhere for a reason.

We had a 48 inch range with 48 inch 1200cfm hood in previous house. Was installed in 2002. No makeup air. We are still alive. Lived there for 14 1/2 years. We have a 48 inch range in current house with 48 inch 1200 cfm hood with passive makeup air system.

Me too vinmarks...still alive...even all of my 4 kids are still kicking and well...

@Patricia Colwell Consulting: Please edit your submission. I think a cut-and-paste went awry. The intended information is useful.

@vinmarks: A defense of proof of survival against an argument for improved health is a tad specious methinks.

@User: You are correct that 400 CFM is in the International Building Code, but most municipalities in most states have to adopt building codes by publication date and they may do so partially, or with exceptions.

kaseki back when I had no makeup air it wasn't required. Didn't even know it was a thing. I'm not saying to forgo makeup air just stating that back then we didn't have it and we survived.

As far as the number of CO poisoning deaths go per year how many per year are due to someone using a high cfm range hood without makeup air?

We had a 48 inch range with 48 inch 1200cfm hood in previous house. Was installed in 2002. No makeup air. We are still alive. Lived there for 14 1/2 years. We have a 48 inch range in current house with 48 inch 1200 cfm hood with passive makeup air system.

I presume that you drive/ride in a car somewhat frequently as well? Or that you walk or bicycle to places? And you're still alive?

Does that mean that driving in a car isn't dangerous? For anyone on any road anywhere? Walking and bicycling are also completely safe, no risks? There is therefore no need to make any of our roadways safer? Because YOU have not been killed or disabled yourself?

Last year drivers in the U.S. killed 39,000 people. If our roads were designed to the same CROW standards as Sweden and The Netherlands then 33,000 of those people would still be alive and unharmed today. But because YOU haven't been killed then there is no need to pursue safer roads or utilize the designs that make The Netherlands so much safer? You are after all, proof that our roads are safe? YOU are the barometer?

Thanks i didn’y bother fixing it BTW not cut and paste but just a skip somehow

opaone no one is saying not to put makeup air in. Where did I say not to put makeup air in with a high cfm hood? I simply stated that back then we had no makeup air and didn't die. It wasn't required and most people didn't know it was even needed.

IIRC, last year 230 people in MN were hospitalized for CO poisoning and 17 died from it. 2 of those deaths were attributed to lack of proper make up air resulting in backdrafting of a furnace or water heater (presumably by a range hood but could have been fireplace or something else). 2 isn't many. Not a big deal? Nothing to worry about?

Death actually isn't the big risk w/ CO poisoning though. Neurological and coronary damage are. Same for over VOCs. Just because you've not died doesn't mean that you've not already incurred brain or heart damage. Nor that this damage isn't likely to result in a heart attack, lower cognitive function, Parkinsonians or numerous other ailments.

People in Blue Zones not only live longer but are much healthier for those years. Less than 5% of their life is diseased. The OECD average is 18% with Sweden the lowest at 9% and the U.S. the highest at 23%. Daily moderate activity (E.G., walking & bicycling) is generally believed the number one determinant of health with diet a close second. We know that IAQ is a part of this but we don't yet know how much of a part nor what components are most important. We are learning that high levels of CO2 play a part as does exposure to CO, NO2, Formaldehyde and other VOCs.

You're alive but will you have a heart attack caused by living in a house with poor air quality? Or experience lower cognitive function and incontinence for the last 20 years of your life? Maybe, maybe not. As well, you and someone else could spend the exact same amount of time in the exact same environment and one of you experience no affects and the other experience severe effects.

Just because YOU don't experience negative health effects from poor air quality doesn't mean that nobody will.

@Celadon: You are correct that 400 CFM is in the International Building Code, but most municipalities in most states have to adopt building codes by publication date and they may do so partially, or with exceptions.

To build on this a bit. There are many code elements that are regional or geographical in nature. What is critical in Florida may be very different than Winnipeg.

MUA requirements are not nearly as important in Santa Barbara CA as in Minneapolis MN. I don't know that I would consider MUA at all critical in Santa Barbara while it is in MN.

After spending 9-12k on a range i wouldn’t skimp or take shortcuts on the vent...(or add bends)...and tho’ you asked a specific question i think lots of helpful comments were offered..so it does seem inappropriate..if not rude...to denigrate the offerings

Changes to code happen every 3 years. MUA was part of the 2009 code cycle changes. Even jurisdictions that are a couple of code cycles behind aren’t that far behind. It IS almost 2021.

Bends are often unavoidable. One just has to compensate for them in the design. The relevant requirement is to have a blower with a fan curve such that the sum of the pressure losses from cooktop to exterior environment and from exterior environment to the cooktop allows the necessary volumetric flow rate (CFM) to ensure containment of the captured cooking plumes. In doing this, there is a requirement to not depressurize the residence such that combustion appliances are back-drafted. These topics are treated extensively in this forum.