There's a vampire in your house, and it's costing you hundreds of dollars every year.

Even when they're turned off, many of your appliances are still sucking electricity out of the wall. They're staying warm, waiting for you to click the remote... or plug into the charger.

Twenty or more items in the typical American household run up your electric bill when you're not looking.

Some of the things that use the most juice while you sleep are your DVR, garage door openers, answering machines and computers.

Brian Manthey, a spokesperson for We Energies, said it costs us all.

"While they're not great amounts on their own, if you have a few of them in your house they'll add up over the course of a year," he said.

We visited the Engstrom house in West Bend to find out just how much extra the family pays for unused appliances.

We brought along a device called the "Kill A Watt" to help figure that out. The device measures the amount of electricity used by everything you plug in. It even measures the energy used when something's turned off.

"I thought when you turn something off, it's off. That it's not really still taking energy and using it," Chris Engstrom told us.

Well, it should work that way, but we found it doesn't.

The Engstrom's answering machine, TV and garage door opener were all using power.

The biggest culprit: the Engstrom's computer system. If they never turn it on, it will still cost them $30 a year in power.

So what should you do? We asked We Energies' Brian Manthey.

"If you put them all on a power strip, and just turn the power strip off when you're not using it or at night, that will help," he said.

Follow those steps, and you could save $200 a year.

FYI, the "Kill A Watt" device is available online for about 20 bucks.