Real estate appraiser Dan DeHart jogged each day at 6 a.m. until a surge in business three months ago left no time for obligations like filing a tax return, let alone the indulgence of a daily workout.

"I still put the same pair of running shoes on, but I'm running to work instead of to exercise," the 36-year-old Alexandria resident said. "My recreation now is eating. I'm gaining weight, and I'm worried I won't find time to get an extension on my taxes."

DeHart relishes the hardship. It means he's reaping a bonanza in windfall earnings. Like hundreds of professionals who support the home-loan industry in metropolitan Washington, he finds business booming as a dramatic drop in interest rates sends thousands of borrowers scrambling to refinance mortgages.

Lawyers, title insurers, surveyors and appraisers who play an integral part in mortgage lending say demand for their services has doubled, tripled and in some cases quadrupled since January as lenders and consumers here and nationwide seek help in restructuring loans. Backlogs abound as companies and one-man offices race to keep pace by working long hours and hiring new staff.

"We're closing transactions seven days a week," said Philip A. Gorelick, a partner in the law firm of Melrod, Redman & Gartlan in the District. "We have people waiting in line to use conference rooms." He said that the firm plans to add eight new lawyers by midsummer to its 42-person office.

"There's just so much work it doesn't matter if you are a small shop or a large shop, you're just backed up," said Bill Onufrychuk, an appraiser in Fairfax.

"We're swamped," said Linda McKee, a loan processor for Perpetual American Mortgage Co. "We're hiring as many loan processors as we can find."

The boom is fueled by consumers who want to shave off hundreds of dollars in monthly mortgage payments by taking advantage of cheaper rates. But while the cost of refinancing can be substantially less than getting a mortgage in the first place, it is not free. And each extra fee falls to professionals whose services are required in the refinancing process.

Lenders collect fees called "points" that run from 1 percent to 3 percent of each loan they make. Refinancing brings them extra fees, but it also brings them risk: Low-interest loans could prove unprofitable if rates rise and depositors demand rates that are higher than those lenders earn on loans.

But those in support businesses, such as title examiners and brokers, don't have such worries. They make a profit on every fee they take regardless of whether rates go up or down.

To refinance a typical single-family house, for example, a consumer must pay from $200 to $250 for an appraisal of the property and then $30 to $40 for a credit check. These services are required even though they were performed for the original loan.

No title is transferred in a refinancing, so homeowners are spared a fee for that transaction, which can range from several hundred to several thousand dollars. But they still must pay hundreds of dollars for a title search and to close the new contract.

The charges add up.

A good appraiser might perform 700 property valuations in a typical year, taking in $175,000, home-loan industry executives say. This year that amount could easily double, pushing a typical annual income to $350,000 or more. Other professionals say they are likely to see similar gains. 'Boom Year' Foreseen

"It will be a boom year," said Brenda Melton, chief executive of S&L Mortgage Corp., a Bethesda-based subsidiary of Shannon & Luchs that provides all the services required for refinancing. "I've never seen such volume."

Finding qualified employes is not always easy. Home-industry executives say the biggest shortage is for appraisers. A recent rise in foreclosures and loan losses from overvalued housing has caused many lenders to tighten standards on whose appraisal they will accept.

Appraisers say their only alternative is to work longer hours and turn some new customers away. Even so, a job that would have been completed within 10 days three months ago now takes four to six weeks to finish, lenders and real estate brokers say. The delay could slip to three months come summer, the busiest season for home buying, they say. Overload Slows Processing

Demand is slowing nearly every step in the process, too. At Perpetual, for example, the number of telephone calls regarding refinancing has doubled to 800 a day, making it impossible to answer every call as soon as the company would like.

"People have been pretty understanding, but some scream at me if they've had to call several times before getting a response," said Debbie Robinson, Perpetual's receptionist. When she was out sick last week, the company had to replace her with two temporary staff to cope with the onslaught of calls.

Some consumers have gotten downright nasty. Pat Young, a vice president at Real Title Co. in Fairfax, said she had one "irate client" during a settlement who, not understanding the reason for the amount of paperwork involved, stomped around a conference room and then sat down in a huff on a credenza.

"He broke the thing off the wall," said Young. "His wife could not keep a straight face for the rest of the meeting." Young said that the company did not charge the man for the cost of repairing the sideboard and was too busy to hold any grudges.

"The cases are just pouring in," Young said. She said that the company's usual volume of 10 refinancings a month has jumped to 70, forcing it to hire an additional lawyer and reorganize its staff to handle the load.

In the hope of winning new sales, the real estate company of Long & Foster in Fairfax offers free advice -- but only to former customers -- on where to go for refinancing.