Check:  www.energystar.gov — check site for qualifying replacement models and more details.

Odds are, somewhere in your house is a black hole that’s sucking down a constant stream of wasted energy, and wasted money.

If you’re like most homeowners, the main culprit is the hulking tank that’s constantly keeping water hot for whenever you might decide to jump in the shower.

“Water heaters are one of the most energy-consuming appliances in the home,” says Rich Wenzel of the Sustainability Network. They can account for 14 percent to 25 percent of the energy consumed in your home.

“They’re keeping 30 to 100 gallons of water at, say, 120 degrees 24 hours a day, 365 days a year — and therefore offer an area of significant savings,” he says.

The savings potential for most homeowners is now greater than ever, thanks to the Federal Tax Credits for Consumer Energy Efficiency.

In the case of water heaters, homeowners can get up to $1,500 back at tax time by installing a qualifying model (listed at energystar.gov). The tax credit covers 30 percent of the total cost — including installation.

Plumber Andrew Twidwell of ABT Plumbing, Electric, Heat & Air says most of the water heaters he sees in Grass Valley would be ideal candidates for replacement.

“Upgrading makes sense for anyone who has a water heater that is rated at less than 80 percent efficient. Most conventional water heaters you find in Nevada County have energy ratings of 52 percent,” he says. You can find your heater’s efficiency rating on the large yellow Energy Star sticker on the tank.

“On-demand, tankless gas water heaters are rated at above 80 percent and do not use energy when there is no demand for hot water, he says. Also, “tankless water heaters can easily exceed 20 years of use and maintain very high efficiency. Conventional water heaters average between 10 and 15 years in Auburn.”

Andrew says “the impact of this modest upgrade on a wide scale would be significant.”

“If most homeowners installed one of these hot water systems, the country as a whole would likely reap an overall energy savings of around 10 percent,” Andrew says. “With homeowners saving around 25 percent of their overall energy bills.”

Other tax credit options

Replacing your water heaters may be the most affordable, widely available way to take advantage of the tax credit — but it’s just one of several options. Tax credit incentives are also available for insulation, air conditioner replacement, furnaces and a number of other improvements.

A number variables determine whether it makes financial sense for a homeowner to invest in one of these options, says Ryan Jones of Home Inspections, a Grass Valley-based energy auditor.

First, he says, it depends on whether a homeowner is interested in helping save the environment or just saving money. If the latter, then most energy-efficiency upgrades will take at least a few years to pay for themselves in lower utility bills.

Insulation tends to pay for itself the most quickly — in four to seven years, Jones says. Woodstoves take longer at up to eight years if they’re used consistently — less if the wood is free.

In the case of roofs, windows and doors, Jones says it likely only makes sense to replace those once they’re worn out.

“If the windows and doors are moderately bad or not that bad, they will not be cost-effective to replace,” Jones says. And even if they’re very bad, they might not make sense to replace. “If the windows and doors are that old, the house probably has other areas that need improvement that would be more cost-effective.”

Nevertheless, Jones says the tax credit seems to be generating more replacement of windows and doors than any of the other energy-efficiency upgrades.

“HVAC has picked up some, but windows and doors picked up the most, because of window and door company advertising,” he says. “I think those are the only areas the tax credits have had much affect.”

No tax credit, but savings

It won’t make sense for many homeowners to take advantage of tax credits, Jones says. The upfront costs may be too high, or they may not plan on moving in a year or two. Regardless, he says there are several simple, cheap steps all homeowers can take to reduce their energy consumption — and their bills — now.

• Air-sealing the house by caulking exterior window frames and using foam weather stripping around leaking door jambs.

• Sealing air ducts — with a high-quality, aluminum-backed duct tape (not just ordinary duct tape), or with duct mastic, which does a better, longer lasting job.

• Hanging heavier drapes that extend to the floor over drafy windows.

• Using an insulating blanket on your tank water heater, and insulating foam around hot water lines.