Faster than a pizza oven; can heat your home and cook your food at the same time. Super oven? Well, almost ...

NEIL MANDERS can cook a pizza in it in five minutes. Patty, his wife, calls it ``better than a microwave.'' The four Manders children use it to dry fruit - and it also helps heat their 3,000-square-foot Vermont home. This six-foot high gray stone mass with a traditional arched metal door sits in the kitchen, pleasantly warming home, hearth, and the cat - who usually sleeps in the niche meant for firewood. What exactly is it? A soapstone bake oven made in Finland by a company named TuliKivi. Soapstone is eight times more absorbent than conventional masonry, and stays hotter longer on the same amount of fuel. Consisting roughly of half talc and half magnesite, the stone is unusually easy to work with and is quite beautiful - similar to granite.

It has been used extensively in Finland, where a huge deposit in the southeast supplies soapstone for stoves in a country whose average winter temperature rarely tops 25 degrees F.

The Manders's oven, which measures about four feet wide by two feet deep, together with a soapstone heating unit of roughly the same size keeps their whole house at a constant, comfortable temperature of 68 degrees F., even in the most frigid New England weather.

``We used to have electric heating, and it was so incredibly expensive,'' says Mr. Manders. Using it for a couple of hours during the ``peak'' periods could cost as much as an entire day's worth at the ``off-hour'' rates, he explains. ``The bake oven/heating unit is costing us half as much to heat our home - which is now twice as large because we added a wing to the house.''

Mrs. Manders says that at first she was intimidated by the thought of using the oven. ``I like to do things precisely and I like exact directions. I think most Americans do. I had to get used to converting the built-in centigrade thermometer to Fahrenheit for recipes, and adjust to sort of cooking by feel. I never thought I'd get the hang of it, but now I prefer it and do almost all my baking and cooking in it.''

She uses it for reheating, baking, and roasting, she says. ``It cooks things amazingly fast. And I don't have to worry about the kids burning themselves, because the outside is never too hot to the touch.''

Using the same principle of serpentine flues as masonry heating units (such as the so-called ``Russian fireplace''), brick baking ovens have been used for centuries to bake bread in Europe. The use of soapstone makes a good thing better: It creates a steady, even heat that lasts longer and takes about half the time to heat up as regular refractory brick.

TuliKivi has taken the idea one step further by adding a cookstove top for use comparable to a conventional range. And by firing it twice a day, the oven will do double duty as a stove and heater.

Paul and June Kemp live in Greenfield, Mass., about 20 minutes south of the Manders home. They, too, have a Finnish bake oven and cookstove. Although Mrs. Kemp has not ventured too far, culinary-wise, with her year-old oven, both she and her husband can't believe how well it heats their home.

Standing as a handsome divider between the kitchen and living room, the massive pewter-colored oven takes about an hour to heat their home. Mr. Kemp says he plans on using two cords of wood this year, compared to the four or five cords he used to burn with an iron woodstove.

``I have much less concern about this [cookstove-heater] than my old woodstove. There is no creosote build-up because of the total clean burn, and no worry about falling stovepipes and the other woodstove-related problems,'' he says.

Albie Barden, a well-known New England stove mason, and vice-president of Maine Wood Heating Co., says, ``Woodstove heat people have known for years that masonry heat is better, but couldn't sell people on the concept alone.'' He adds that masonry stove mass production capabilities were lacking.

``TuliKivi's stoves have changed all that. They are high-quality, but most of all they appeal to the American aesthetic. People react to the look first. Then when they feel the heat radiating out, they are totally convinced.''

``They use a time-honored interior flue system that works well,'' says David Lyle, author of a number of books and articles on masonry heating, president of Heating Research Co. in Acworth, N.H., and a consultant to TuliKivi.

``Construction is modular, so it's easy to put together. Soapstone is a traditional and marvelous material for a heater of this kind - soapstone heaters go back for centuries in Europe, as in the United States - it's beautiful as well as serviceable.''

The cost for a typical TuliKivi bake oven is about $5,000, not including the foundation, which may cost about $1,000.

The company has just purchased a soapstone quarry in Schuyler, Va., which is the largest known vein of high-quality soapstone in North America. This now makes it possible for the modular elements to be mined and finished in the US, and installed by company-trained masons.

It may seem a high price to pay for heating one's home, but the fact that there are some 150-year-old soapstone ovens still in operation in Finland proves that these are defintitely permanent fixtures of lasting value.

On the other hand, the size inherent in masonry heating is the biggest drawback.

``The systems are heavy - they require a foundation adequate to support them, like a masonry fireplace,'' says Mr. Lyle. ``They are expensive compared to iron stoves. Heating response is slower than it is from an iron stove; on the other hand, a masonry stove stays warm long after the fire dies, while the iron does not.''

And they require some effort from the user, a new concept for convenience-oriented Americans.

``Easy as flipping a switch? ... Of course not,'' says Mr. Manders. ``You still have to take care of the wood and haul it in. But that's about the only advantage of conventional heating over my soapstone system.''

Mr. Kemp likes the rigors of using wood for heating. ``Since I grew up with a woodstove, I actually enjoy going out and chopping my own wood,'' he says. ``The only disadvantage is that you have to sort of plan around the firing of the stove. When the fire is out, there's no problem. It's just that hour or so that you have to be there. But that's true of most woodstoves.''