The Senate Finance Committee voted yesterday to extend its newly increased home insulation tax credit proposal to homeowners who install heat pumps, and to provide a spate of new tax breaks for converting dams into hydroelectric plants.

The actions came as the committee continued its work on a round of new tax credits designed to spur energy conservation before turning next week to scheduled consideration of President Carter's windfall profits tax.

With yesterday's actions included, the panel so far has approved tax credits and other measures that would use up 87.5 percent of the $10.5 billion in new revenues that the government would receive from the House windfall tax bill.

Moreover, Finance Committee Chairman Russel B. Long (D-La.) has indicated the panel will water down the House-passed measure by exempting major categories of crude oil from the levy altogether.

The committee's generosity in approving the tax breaks could pose some procedural difficulties later. The Carter administration wants to use the bulk of the windfall tax monies to finance its new synthetic fuels program.

The new Senate budget resolution requires the panel to draft a stiff enough windfall profits tax to raise at least $2 billion in fiscal 1980. If the committee doesn't meet that target, the tax credits could run into trouble on the floor.

Long appears to be taking up the credits first in hopes of pressuring the committee later to approve a windfall profits tax that would raise sufficient revenues to finance these tax breaks. However, it's unclear how well this strategy will work.

The Finance chairman has said he hopes to complete the windfall tax legislation sometime next week, a schedule some observers considered optimistic, since the committee hasn't yet begun talking about the crude-oil tax.

Yesterday's action on the heat-pump tax credit would allow homeowners a writeoff of up to $1,000 -- 50 percent of their costs for the first $2,000 spent -- for installing heat pumps to replace electric systems or to back up solar water heaters.

The proposal, sponsored by Sen. Bob Packwood (R-Ore.), would cost the Treasury $483 million a year in lost revenues by 1985, and $754 million by 1990. The committee voted earlier to provide a similar credit for home insulation.

The panel also approved an amendment by Sen. Gaylord Nelson (D-Wis.) that would liberalize existing business tax rules to provide tax breaks for the purchase of generators to turn small dams into hydroelectric plants.