Depends on what you cook and how you cook and how much output power (BTUs) your new range has.

If you do a lot of greasy cooking with a lot of smoke, yes, you would want a hood that vents outside.

But if you mostly boil water and do low smoke cooking, then you might be OK with the OTR recirculating vent.

Though, most would say you should get a proper hood and vent it outside, it will always be better. Some people are just not in a position to do that though.

So, to determine how powerful your new range is add up all the BTU outputs of all burners and that total will give us an idea of the max your range can do.

I am no expert and I'm sure others will chime in to help as well.

Phil

Its a small 4.4 cu ft basic range. 40,000 BTU cooktop.

It really depends on your local codes.
Most codes some will allow a recirc hood over a gas stove but recently some cities are changing their codes to have gas stoves to have a hood that vents to the outside but they allow electric stoves to have recirc.

From what I have read the rule of thumb is to divide your total BTU's by 100, so you would want a 400 CFM hood for that range.

Now, that being said that is assuming you are running all burners on high all the time to need to 400 CFMs.

I personally have 6 speeds on my hood and I am normally at 2 or 3 unless i am doing 4 or 5 pots/pans or something really greasy.

I think I would look in to local codes as well as Jakvis said, but otherwise you might be able to get away with the OTR recuirc you have, as long as you can live with that.

If it were me I would upgrade, but again that might be way out of the budget or just not feasible.

Phil

One other point for grandmum.

Most over-the range (OTR) MWs can be either vented or recirculating. Are the range & OTR against an outside wall? If so, the OTR can vent straight out the back through the wall. Parts for this can be had from many hardware stores.

I think if her local codes required outside venting, the installer wouldn't have installed the stove w/o it. As far as I know, outside venting is not required for gas stoves where I live.

I'm no expert, but I see no reason that gas would have more of a need than electric for outside venting. I lived in my house for several years with recirculating and gas stove and didn't notice any difference from when I had recirculating with electric.

When I had to get a new range hood, though, I paid for the installer to vent to the outside. In my case, they had to go through the attic and out the roof. It didn't add TOO much to the cost of the installation. Hood installers do the outside venting all the time, so they're experienced at it.

With recirculating venting, I had a smoke problem sometimes, with teh smoke alarm going off. With outside venting, that's less of an issue, but I have noticed that it's less energy efficient, since air conditioning and heat from the house also escapes through the outside venting. For taht reason, I made some cards that I cover the hood filters with in the hood.....I use those in the winter. Of course, I have to remember to remove them if I use the hood.

Why would folks say that gas stoves have more of a need for outside venting?

(a) You can find one set of arguments in the recent thread linked below. Check out the further links to the NY Times Article and the Livermore Labs study that are referenced there.

(b) More waste heat from gas burners. The figures I've seen from testing is that gas burners are rated as typically putting less than 40% of their energy into the pots placed on them, and many gas burners are apparently only put around 33% into pans. The rest of the heat goes out into the kitchen. With radiant smoothtop electrics, I believe it is around 55% to 60% and with coil burners, it is supposed to be something like 65% to 70%. With induction, it is between 84% (US DOE tests) and 90% (manufacturer claims).

On putting "cards" over the filters in wintertime, I know what you mean. I had to do the same thing with my kitchen's previous hood when it hung on an outside wall and vented directly out the back. The hood was a very basic model with only one flap (backflow preventer) and that on the outside of the house. We get cold winters here, too, so the leakage was noticable. (When I say cold, I mean it gets cold enough to learn that -40F is the same as -40C.)

Instead of cardboard, though, I would fold a couple of paper towels behind the mesh screen to block the cold air. Still had to remove the paper to use the hood, of course. (I've since remodeled the kitchen with a new hood and a different vent ducting system, and that has pretty much solved my problem had with cold air draining from the hood.)

Here is a link that might be useful: Thread on NY Times article

Well, that's informative, JW! Thanks. Sounds like I didn't get the best type of venting system.

As for having recirculating venting for gas stove, I really didn't notice any difference when I switched from an electric to a gas stove. The recirculating system was generally not good for either gas or electric. But then....I don't cook much. :)