Warm, warm you hear, really warm. That's what Kate and Ralph Rinzler intend to be this winter in their 1878 Capitol Hill town house with its contemporary addition. Keeping warm has kept the Rinzlers in hot water, figuratively and literally, for the last few years. It isn't always easy to be an urban solar pioneer.

In pursuit of the goal of being moderately warm, they now have an oil hot-water furnace, active solar heat, passive solar space and water heat, double glazing, insulated shutters, an insulated attic, a Jotul woodstove, a gas space heater, a gas hot-water heater, weatherstripping, three greenhouses, a soaking tub, a sauna, a hot tub, and, if all else fails, four fireplaces and a wood pile.

When Ralph Rinzler came to Washington in 1967 to start the Smithsonian's Folklife Festival, he bought the nice old house on Capitol Hill, within walking distance of the Smithsonian.

Back then, oil was about 17 cents a gallon, as he remembers. Rinzler, who had lived in Europe, kept the furnace heat set at 65. The upstairs library had a stove flue, so Rinzler bought a "chunk heater," an ancient one, already converted to gas.

He was warm and comfortable--and happy, when his $50-a-month heat bills came due. Except for pulling off the 20th-century front porch, and opening up the fireplaces, he really didn't change the house.

But in 1971 Rinzler married Kate, a California artist and educator, who had big West Coast ideas about things like space, heat and bringing the outdoors inside.

Lucky for Kate's ideas, Ralph had bought an extra lot with the original house. In 1973 they built a 1,610-square- foot (570 unheated) addition, about a third as much space as the existing house.

The new addition is gorgeous. On the main floor is a big room used for folk music hoedowns or Kate Rinzler's batik projects or movies with her students or storage for crafts for the festival or a place for festival participants to crash. One wall looks at the garden across a spacious deck.

Upstairs is a charming master bedroom with a fireplace, wall-to-wall closets, and a balcony greenhouse facing the garden. The bathroom has a wall-to-wall clerestory window that lets in the morning sun to grow plants like crazy. In the bath are a soaking tub and a sauna as well as a shower.

Everybody was living happily ever after until Ralph Rinzler got the bill for one month of heating: $200 (doesn't seem like much now, but that was 1974). "I turned the heat in the addition on one month and off the next," Rinzler said.

"Part of the problem was obvious," said Rinzler. "Our architect for the new addition hadn't seen fit to use double- glazed glass or provide windows that opened or cross ventilation.

"So the first thing I did was cut a hole in the bath and stick an exhaust fan in a cupola. I put another ceiling fan in the upstairs hall, at the top of the stairs. From then on, we never needed air conditioning.

"We bought the Jotul heater and put it in the fireplace. We build a fire in October and never let it die until March. All it takes is two sticks of wood in the morning, or, if it's really cold, two more at night."

Even so, the studio/hoedown room was cold, and so were assorted other rooms. An oriental rug hung in the doorway between living room and hall helped a lot.

In 1977, Rinzler invited the Department of Energy to put on demonstrations at the Folklife Festival. And in no time at all, Rinzler got religion and was a full-time sun worshiper.

When the solar tax credit legislation was before Congress, he consulted architect David Lord and his assistant Mary Reader for architectural and engineering advice on a solar greenhouse or a Trombe wall.

Through a friend at DOE, Rinzler met Joe Pendergpondent.

rass of Wallace Sheet Metal in Gainesville, Ga. Pendergrass was just Rinzler's sort of Georgia Good Ole Boy. "He's as concerned with the moral problems of energy conservation as well as making a buck. He wouldn't agree to sell us the collectors until we said we'd put in more insulation and weatherstripping."

(Solar collectors are boxes with a black bottom and a glass top. Water is piped through the collectors. The sun's heat enters the glass and heats up the water. The heat is then stored, in this case in water tanks. Air is blown across a coil to be heated and then through duct work into the house.)

Pendergrass' collectors were less expensive than other firms' solar collectors, even though he brought a crane from Georgia to put them in. The collectors cost $3,225.

At a DOE solar fair on the Mall, Rinzler also met Craig Nyman, head of Solar Works Inc., who helped install the collectors and the four water- storage tanks, with engineering advice from Eric Peterson.

Not everything went smoothly.

"I was out in California when the collectors came," said Rinzler. "Pendergrass had just put the collectors up on the roof since he had the crane, but Craig hadn't installed them.

"One neighbor down the street, a long way away, said that every time she looked out of her top-floor window she could see the sun glinting off our collectors and they made her feel as though she didn't live in a historic district.

"She got the Capitol Hill Restoration Society to file a complaint against us at the Landmark Commission. Well, Jackie Austin, our neighbor, got up a petition signed with 34 names saying they didn't object to the solar collectors. One of our signers was Richard Chused, a real estate lawyer, who was interested in people's rights to the sun.

"We were saved by architect Hugh Newell Jacobson, a member of the commission. He came around to see what the fuss was about. He took one look at the collectors, suggested we box in the end so it would look something like a cupola and paint the trim and our copper roof black so the solar collectors would look as though they were a continuation of the clerestory windows. It was a perfect solution."

The permit for the collectors and a projected Trombe wall was approved.

Rinzler was so cautious after the collector experience, a year later, that he went back to the Landmark Commission to see if it was all right to put in his Trombe wall. The commission said fine. They weren't seriously concerned because the Trombe wall is on the side, not the front, of the Rinzler house, not really noticeable from the street.

(The Trombe wall is the invention of a French solar expert, Felix Trombe. It's based on the theory that solar radiation passes through glass or plastic and is soaked up by a solid mass such as a masonry wall. During the day, the masonry soaks up the solar heat and at night it radiates it back. An air space between the glass and the masonry becomes a heat duct because of hot air's tendency to rise. An opening at the bottom of the wall brings in the house's cool air, and a second opening at the top takes the warmed air back in. If you don't open up ducts between the Trombe wall and the house, it still warms the house by radiating heat through the wall.)

At the Rinzlers', Nyman cut a hole near the floor in the dining room to collect the cold air and then another in the upstairs library for the warmed air to escape. Vents at the top and bottom of the Trombe wall itself ventilate it in summer.

"The Trombe wall also acts as insulation for that side of the house," Nyman said.

Instead of glass, Nyman used Exolite, a type of acrylic glazing, framed with pressure- treated lumber. The existing brick wall has been painted with a thin preparation of water-thinned black paint.

"I didn't want the paint to be too thick because the natural uneven texture of the brick helps to trap the heat," Nyman said. "I used the Exolite so we could get a custom fit and because it's more shock-resistant than glass. It's self-insulated, with channels that run up and down. It costs $3.40 a square foot and comes with its own fastening system, aluminum battens and a flexible stripping that stands up to the sun."

The wall, made of three- foot-wide panels of varying lengths, covers 700 square feet and cost $11,000. Soon after its completion last April, Rinzler found that it was not a hit with all the neighbors. One old friend, Harry Lowe, told Rinzler, "I'll still speak to you but only because I like you for other reasons."

A coat of black paint on the aluminum framing improved the wall's initial appearance and now Rinzler is training wisteria up a trellis over the wall so the vine's leaves will cover the structure in summer.

In the meantime, Nyman had installed Window Quilts covering most of the floor-to-ceiling glass in the master bedroom and the studio.

The Window Quilts, not everybody's idea of elegance, have a patterned stitching and are beige on the inside and white on the outside. They roll up and down like a normal shade but in a track that keeps them close to the window. Made by Appropriate Technology in Vermont, they cost $5 to $6 a square foot installed, including hardware, quilt and runner, or about $50 for a 3-by-5-foot window. Drapery and curtain workshops can fabricate similar systems.

Where the quilting wouldn't fit because of the angle of the wall, Nyman built insulated shutters, two panels of plywood sandwiching a piece of rigid insulation. Nyman figures the insulated shutters are cheaper. But the shutters take up a lot of space in the room when they're opened.

David Cawley, of Anacostia Energy Alliance, a group that demonstrates conservation and solar technology and makes energy audits, has just analyzed the Rinzler house. He notes that for $1.50 a square foot you can make a simpler shutter of aluminum framing and rigid insulation, covered with wallpaper or fabric. It can be set into the window without hardware.

Cawley was astounded to find that the Rinzlers' bills for gas and oil (including cooking, back-up hot water and water-heating for the 800-gallon hot tub) totaled only $631.83 last winter-- not bad at all for a 3,600-square-foot house. These bills reflect the solar collector savings but preceded the building of the Trombe wall.

"I suspect that the Trombe wall's main benefit will be in making the whole house more comfortable, rather than saving so much more on heat," Cawley said.

As for the Rinzlers, well, they're already talking to Nyman about double- glazing the south greenhouse.

You can't get too much of that solar heat.