The Biden administration, ever eager to flash its climate change-fighting bona fides, has proposed mandating costly new technology for yet another common household appliance — the hot water heater. And just for good measure, they also have decided that gas-powered portable generators are no-nos now as well.

The new rules teed up by President Biden’s Department of Energy would require electric hot water heaters to include new heat pump technology and gas-fired ones to include condensing technology beginning in 2029. The department says the new rules will make buying and installing new heaters more expensive but insists that most customers will recoup those costs over the life of the appliance via lower energy bills.

“Today’s actions — together with our industry partners and stakeholders — improve outdated efficiency standards for common household appliances, which is essential to slashing utility bills for American families and cutting harmful carbon emissions,” energy secretary Jennifer Granholm said in a statement announcing the proposed rules. “This proposal reinforces the trajectory of consumer savings that forms the key pillar of Bidenomics and builds on the unprecedented actions already taken by this Administration to lower energy costs for working families across the nation.”

Ms. Granholm says the rules, which still need to be finalized after a period of public comment, will reduce carbon dioxide emissions by half a billion metric tons over 30 years. With this latest proposal, the Biden administration has now targeted the efficiency standards of 18 different home appliances — from gas stoves to dishwashers to air conditioners — in what it says is Mr. Biden’s “ambitious efforts to tackle the climate crisis.”

Republicans in Congress, already miffed about the proposals for other appliances, said the move is yet another example of the administration’s regulatory overreach in the name of combating climate change. A Kentucky congressman, Thomas Massie, took to Twitter over the weekend to complain, saying, “Leave us alone.”

“These products already exist in the free market,” Mr. Massie said. “Consumers should decide whether the upfront cost of a heat-pump water heater is worth the possible long term savings. In many cases, the monthly savings never make up for the upfront cost of the equipment.”

The new rules regarding portable generators come from the Consumer Product Safety Commission and ostensibly are being proposed as a public safety initiative as opposed to a climate change one. The commission has determined that there is an “unreasonable risk of injury and death associated with acute carbon monoxide poisoning from portable generators.” The agency says an average of 85 Americans have died yearly from poisoning attributed to the generators — mostly by people who ignore warnings about operating the devices in enclosed spaces.

The agency’s solution is to mandate that manufacturers reduce the device’s carbon monoxide emissions and require them to install devices that automatically shut them off when emissions reach a certain level. In comments on the new rule, makers of the generators say 95 percent of the generators currently on the market will not be able to comply with the new standards.

“Portable generators are an essential consumer product that are frequently used to provide lifesaving backup power when the electricity grid fails during natural disasters and other emergencies,” lawyers for Harbor Freight Tools, a California-based tool retailer with more than 1,400 stores in 48 states, told the commission. The commission should “avoid making generators unavailable or unattainable by the millions of Americans who will rely on them in the face of increasingly severe heat waves, cold spells, and extreme weather.”

An industry group, the Portable Generators Manufacturers Association, said the commission’s proposal that the new rules take effect in less than six months also is unrealistic. It will take at least three years for manufacturers to develop and produce compliant generators, and an edict that forbids the companies from stockpiling older, non-compliant models in the interim will likely lead to shortages of the devices. The new compliant models, the group says, will cost more, perform worse, and have a shorter life span.

The five million or so Americans who rely on portable generators when power from America’s increasingly overstretched grid fails will be left out in the cold if the new rules are allowed to go into effect, the association says.