Canners are essentially very large pressure cookers, but a dedicated canner, as opposed to using a pressure cooker as a canner, will make canning much easier -- an may increase food safety as well. While you can buy small canners, the best have very large capacities so you can seal a number of jars at once, thus cutting the amount of time it takes to finish the job. Safety is also crucial on these large cookers and the best feature metal-to-metal seals so that there's no way for air to slip out or gaskets to give way.
The top-rated All American 921 21-Quart Pressure Cooker/Canner (Est. $210) uses a metal-to-metal seal, as well as a safety-control valve and over-pressure plug as backup safety features; although most owners say they've never needed them. It has pressure settings of 5, 10 and 15 psi. This all-aluminum canner is extremely high quality, according to owners; many expect to hand it down for generations. It has an easy-to-read pressure gauge that's more precise than gauges on cheaper models.
This 21-quart All American canner will accommodate 19 pint jars or seven quart jars, and most agree that it's a perfect capacity -- large enough to get through the job quickly, but not so large as to be unwieldy. Although be warned: this canner is heavy when full and you should plan your work accordingly. It also is not recommended for use on glass cooktops. While most buy it to use as a dedicated canner, we saw plenty of reports from people who use it to make large batches of food that are traditionally made in pressure cookers, like soups, broths and stews. It will also accommodate an 11-pound turkey. The All American canner also comes in 10.5 quart, 15.5 quart, 25 quart, 30 quart and 41.5 quart capacities.
Presto is a top choice in pressure cookers, and they also make a very well-reviewed canner, the Presto 01781 23-Quart Pressure Canner and Cooker (Est. $90). It's a fraction of the price of the All American and has a slightly larger capacity. It holds 24 half-pint, 20 pint or seven quart jars. It's reported as extremely easy to use, and many say that they can "hear" when it reaches the correct pressure, so they don't have to watch it like a hawk. It also doubles as a boiling water canner for jellies, jams and salsa.
Unlike the All American, the Presto 01781 has a rubber gasket and there are the usual complaints of the gasket failing -- sometimes after just a few uses, sometimes after quite a few. Many owners just opt to buy an extra gasket at the time of purchase so they have a backup. For the initial low price, they say, it's worth replacing the gasket occasionally. If you don't need a canner that's quite so large, it's also available in a 16-quart capacity.
The Presto Pressure Canner includes an impressive, 12-year warranty, as compared to the All American's one-year warranty; although, since the All American is described as practically indestructible, that short warranty period doesn't concern us. In addition, the gasket on the Presto is not covered under the warranty and that's the one part that's likely to be a problem.
However, if you don't need to cook a large turkey, don't need a dedicated canner, or don't can in large batches, we recommend that you head over to our discussion of the best stovetop pressure cookers, elsewhere in this report for our take on the best traditional stovetop pressure cookers. Our Best Reviewed choice in that category, the Fagor 8-Quart Stainless-Steel Pressure Cooker (Est. $110) is roomy enough to use as a small canner, yet small enough for everyday cooking. If you're looking for a pressure cooker that is highly versatile and has "set-and-forget" convenience features, you may be interested in reading our picks for the best electric pressure cookers -- though as noted in the intro, electric pressure cookers aren't really suitable for use as canners.