Homeownership can be costly, beyond your monthly payment. Among other expenses, you’ll need to pay to maintain — and occasionally troubleshoot — your plumbing, electricity and HVAC systems. One way to save money is to attempt your own home projects rather than enlisting a professional. But before you grab your toolbox, keep in mind that not all repairs are created equal. If you don’t have the experience and tools to do the job right, you could end up with costly problems later on — and, in some cases, risk damage to your home and your own well-being.

Here are some projects you can handle on your own — and a few you should always leave to the pros. And, of course, everyone has different skill sets and comfort levels when it comes to home projects. Never take on anything you are not sure you can handle safely.

5 projects you can tackle yourself . . .

Replacing sink faucets. Whether yours are looking dilapidated or you just want a more modern look, you may want to swap out a sink faucet at some point. “It’s usually as easy as choosing your favorite style faucet, removing the existing one and installing the new one,” says Richard Lee, owner of Lee Brothers Construction in Huntsville, Tex.

You’ll have to do a bit of recon first in terms of hole placement. If it’s a single-hole faucet, it’s simple to swap it out for a single-hole replacement. If it has multiple holes, you have to measure the distance between the holes and take that information to a salesperson at your local hardware store. They can help you find the proper replacement.

It’s worth noting that replacing a shower faucet can be more complicated. If you’re purchasing an identical faucet replacement — meaning the same model and brand — installation is fairly straightforward. But if the valve in the wall has to be replaced, Lee says, it will require some plumbing work, and you’ll be better off calling a professional.

Changing your HVAC filter. Swapping out your HVAC filter is a simple way to maintain your unit’s efficiency, lower your utility bills and improve your indoor air quality. Chris Koehner, owner of Halo Heating and Cooling in Nashville, recommends adding this task to your routine maintenance schedule; typically, the filter should be replaced every three to six weeks. If you have trouble remembering to check your filter, tie it to when you pay your electric bill. And if you’re experiencing HVAC issues, check that you’ve changed your filter recently. If you don’t think that’s the problem, call a professional, because they can help you remedy more complicated issues.

Fixing a running toilet. Loren Bottem, plumbing manager at Genz-Ryan, a plumbing, HVAC and electrical company in Minnesota, says most homeowners can solve one of the most common bathroom problems — a persistently running toilet — on their own, both effectively and without any major risks to their plumbing. The best way to do that? Replace the flapper or the fill valve inside the tank. You can find a kit at any home improvement store, but make sure to get the right type of flapper or fill valve replacement. Look at the one you’re replacing before you head to the store and, if possible, bring the old one with you or take a photo to compare while shopping. And follow the instructions on the package.

Flushing your water heater. According to Bottem, water heaters can collect sediment over time, so they require yearly maintenance to maximize energy efficiency and improve their life span. Luckily, you can take care of that chore yourself. Bottem suggests flushing the water heater as often as every few months — or more often if you have a lot of minerals in your water supply. Follow the instructions that came with your water heater. If you don’t have the manual, find it online by searching the water heater’s brand and model number. Flushing one typically involves turning off the gas or electricity supply, switching off the cold-water valve and turning on a hot-water source in your home. Then, attach a garden hose to drain the heater into a bucket. Finally, turn on your cold-water supply, and allow the water to wash out the last of the sediment.

Restoring your hot-water supply. If you find yourself running out of hot water, even when you’re not simultaneously doing the laundry and taking a shower, you can attempt to reset the heating element on your water heater. If you have a gas unit, Bottem says relighting the pilot light — if you feel comfortable doing this — often solves the problem. To reset the power on an electric water heater, you may need to flip the breaker. If your water heater is fan assisted, then you may need to press the reset button on the outlet associated with it.

. . . and 5 projects you should always hire a pro for

Cleaning your HVAC unit. Over time, outdoor HVAC units can collect dirt, dust and pollen, but cleaning it isn’t a matter of hosing off the unit yourself, which will push debris farther into the system. According to Koehner, most homeowners don’t have the proper equipment or expertise for this delicate procedure — and one wrong move can create issues that will shorten your HVAC’s life or cause it to malfunction. Instead, call an HVAC pro, who will remove the top of the unit and spray the coils with a special cleaner that will lift dirt without damaging the aluminum coils.

Replacing a shower valve or cartridge. If your shower drips after you turn it off, it may be time to replace your valve, the piece behind the wall that connects the hot- and cold-water lines, or the cartridge, but Bottem says that’s not a job for the average homeowner. “These can easily break, causing you to shut the water off to the entire home until you can get the professional plumber out to replace it,” Bottem says.

Replacing pipes. Along the same lines, attempting to replace old, worn-out pipes could result in expensive plumbing repairs. Ryan Thompson, a residential plumber in Miami, says it’s easy (and potentially expensive) to unknowingly install the wrong type of pipe. “One of the most common home maintenance mistakes that I have to consistently fix for people when it comes to plumbing is using different types of pipes when replacing old, worn-out ones,” he says. “If you have to force the pipes together and they still require tape to better secure them, that’s a sign that it’s not properly connected.”

Removing mold. Jack Miles, owner of Sarasota Mold Pros in Florida, says mold can be harmful if accidentally ingested. If you suspect you have mold, it’s best to hire a professional to ensure it’s removed properly and safely. “Mold’s roots are usually located deep behind the walls,” Miles says. “However, when a regular person cleans mold by themselves, they usually just clean the wall’s surface and not the mold’s roots.” If that happens, it will grow back, leaving you both frustrated and vulnerable to the mold’s effects.

Most electrical work. Although some homeowners may have the skills to install a light fixture, more complicated electrical work — such as updating your home’s outdated wiring or tinkering with a circuit panel — is generally too risky for most people. That’s why Ben Kolo, owner of Mr. Electric of Central Iowa, a Neighborly company, recommends all entry-level DIYers hire a pro for electrical work. “There are simply too many things that could be done incorrectly that can cause fires or injuries,” Kolo says.

Ashley Abramson is a freelance writer in Wisconsin.