Missouri leaves plumbing permits to cities and counties, and many in the St. Louis area require one to replace a water heater. The new heater also has to meet the local plumbing code, including the temperature and pressure relief valve, a safety valve that opens if the tank gets too hot or builds too much pressure.

Check with your city or county before starting. Gas models also need venting that carries exhaust outside and a gas connection tested for leaks, which is why many homeowners hand the job to a plumber.

When a pipe bursts, check for electrical danger first. If water has reached outlets, cords or the electrical panel, stay out of that area and call your electric company before doing anything else.

If you can reach the main water shut-off valve without stepping into water, turn it off to stop the flow, then call a plumber. Never walk through standing water to reach a valve or a breaker.

An upstairs that runs hotter than the main floor is common in two-story homes, because the rooms under the roof gain heat from the attic all afternoon. Undersized return vents upstairs, leaky ducts in the attic or a system that's too small can make the gap worse.

A technician can measure the airflow to each floor. The fix may be balancing, adjusting the dampers inside the ducts so more cool air reaches the upper floor, or adding a return vent upstairs.

Air conditioner repair is the answer when the system blows warm air, freezes up or won't start. A system that cools fine but hasn't been cleaned since last summer needs an Air Conditioner Deep Clean and Tune-Up.

Replacement is worth a look when a 12- to 15-year-old system needs repair after repair, or when the compressor, the pump that moves refrigerant through the system, fails. On Time Experts Heating, Air & Plumbing will show you what each option costs.

Rooms that stay colder than the rest of the house usually have an airflow problem rather than a heat problem. Common causes include a dirty filter, closed or blocked supply vents, a dirty blower wheel, leaky ducts, and rooms over a garage or at the far end of the duct run.

A technician can measure how much warm air reaches each room and find where it's being lost. Sometimes the fix is a damper, a metal flap inside the duct that controls how much air goes to each area.

Furnace repair fits a furnace that won't heat, keeps shutting off or makes a new noise. A furnace that runs fine but hasn't been cleaned since last winter is due for a Furnace Deep Clean and Tune-Up.

Replacement starts to make sense when a furnace is around 15 years old and the repairs keep coming. On Time Experts Heating, Air & Plumbing can test the furnace and lay out the repair and replacement costs for you.