Start with the type of heater you have
Most Pennsylvania homes have a tank-type water heater in the basement or a utility closet, fuelled by natural gas, electricity, propane or oil. A growing number have tankless units mounted on a wall, and some newer installations are heat-pump water heaters that look like a tank with a fan on top. The symptoms overlap, but the causes and the safe checks are different, so look at the label on the side of the unit before anything else. It lists the fuel, the capacity and, in the serial number, the date it was made.
No hot water at all
Gas tank heaters
- Look through the small window near the bottom. If the pilot light is out on an older model, the thermocouple or flame sensor may have failed, or a draft may have blown it out.
- Newer models with electronic ignition flash an error code on the control. The code and the model number tell a plumber a great deal before they arrive.
- Check that the gas supply valve to the heater is open and that other gas appliances work.
Gas water heaters
If you smell gas near the heater, don’t try to relight it. Leave the house and call your gas utility from outside. Relighting instructions are printed on the unit for a reason: follow them exactly, or leave it to a professional.
Electric tank heaters
- Check the breaker. A double-pole breaker that has tripped is a common cause.
- Many electric heaters have a reset button behind an access panel. If it trips again soon after resetting, a heating element or thermostat has likely failed, and repeated resetting isn’t a fix.
Tankless heaters
- No hot water from a tankless unit often means it isn’t detecting enough flow, the gas supply can’t keep up, or a scale-clogged heat exchanger has triggered a safety shutoff. Error codes on the display are the starting point.
Hot water that runs out fast or never gets hot
- A failed lower element on an electric heater gives you a short burst of hot water, then cold.
- Sediment settles at the bottom of a tank over time, insulating the water from the burner and reducing the usable volume. It is more of a problem where water is hard; your water utility’s annual water quality report lists hardness.
- A broken dip tube, the pipe that carries incoming cold water to the bottom of the tank, lets cold water mix in at the top.
- The thermostat setting may simply be low. The U.S. Consumer Product Safety Commission recommends 120°F to reduce the risk of scalds, which is also a reasonable setting for most households.
Noises from the tank
Popping, rumbling or crackling usually means sediment at the bottom of a gas-fired tank. Water trapped under the sediment boils in small bursts. Flushing the tank can help when it is done early; on a tank that has gone years without it, flushing sometimes stirs up more than it removes, and the noise is a sign the tank is ageing.
A high-pitched whine on an electric heater can come from scale on the elements.
Leaks: where the water comes from matters
- From the relief valve or its discharge pipe. The temperature and pressure (T&P) relief valve opens when pressure or temperature gets too high. Occasional drips may mean high water pressure in the house or thermal expansion with no expansion tank. A constant flow needs attention soon, because the valve is a safety device and shouldn’t be capped or plugged.
- From fittings at the top. Connections and the cold inlet valve can often be repaired.
- From the drain valve at the bottom. Sometimes a loose or worn valve that can be replaced.
- From the tank itself, a puddle under the heater with no other source. Once the inner tank has corroded through, it can’t be repaired. Shut the cold-water valve on top, turn off the power or set the gas control to pilot, and plan on replacement.
Repair or replace?
Questions a plumber will consider with you:
- How old is it? The manufacture date is coded in the serial number on the rating plate; the plumber can read it. Compare the age with the warranty length printed on the label, which is a fair guide to what the maker expected.
- Is the tank leaking? If yes, replacement.
- What failed? Thermocouples, igniters, elements, thermostats and valves are routine repairs on a heater in good condition.
- How much sediment and corrosion is there? Rusty hot water and heavy sediment in an older tank suggest it is near the end.
- Does the size still fit the household? A family that has grown may be better served by a larger tank or a different type of heater.
If you are replacing, it is worth asking about efficiency and about the venting and electrical changes some newer models need. Heat-pump water heaters, for example, need space around them and a condensate drain.
Tank, tankless or heat pump?
If replacement is on the table, the type of heater matters as much as the brand.
| Type | Good fit when | Things to know |
|---|---|---|
| Gas tank | You already have gas and venting | Familiar, fast recovery; needs proper venting and combustion air |
| Electric tank | No gas service, simple installation | Slower recovery; usually needs a dedicated 240-volt circuit |
| Tankless (gas) | You want continuous hot water or need the floor space | May need a larger gas line and new venting; benefits from periodic descaling |
| Heat pump | You want lower electricity use and have room | Needs space and air around it, a condensate drain, and cools the room it sits in |
Ask for a quote that includes everything the new heater needs, such as venting, gas line or electrical changes, an expansion tank and the permit, not just the unit. That is the only fair way to compare options.
What a plumber checks
- Fuel supply, venting and draft on gas units, including signs of back-drafting near the vent hood.
- Elements and thermostats on electric units with a meter.
- The T&P valve, the expansion tank if there is one, and the household water pressure.
- The anode rod, a sacrificial metal rod that corrodes so the tank doesn’t. Replacing a worn anode on a tank in good shape can extend its life.
- Sediment level and the condition of the drain valve.
- For tankless units, flow sensors, gas supply sizing, and whether the heat exchanger needs descaling.
Permits and installation
Replacing a water heater often requires a permit and inspection, particularly for gas units and any change to venting or fuel. Your municipality, or its third-party code agency, can tell you what applies. A professional installation should include a properly piped T&P discharge, correct venting, a sediment trap on gas lines where required, and an expansion tank when the water system needs one.
Simple maintenance
- Test the T&P valve once a year by lifting the lever briefly, with a bucket under the discharge pipe. If it won’t reseat or keeps dripping afterward, have it replaced.
- Drain a few gallons from the bottom of the tank periodically to clear loose sediment.
- Keep the area around a gas heater clear of storage, paint and solvents.
- Ask about the anode rod when the heater is serviced.
Water heater questions
Why do I have hot water in the kitchen but not the bathroom?
That points to a mixing valve or fixture problem rather than the heater, especially in a single shower. If several fixtures are affected, the heater is the more likely cause.
Is it safe to drain my own water heater?
On an electric unit, turn off the power first; on a gas unit, set the control to pilot. Hot water can scald, the drain valve on older tanks can break, and sediment can clog it. If you aren’t comfortable, have a plumber do it during a service visit.
What does the rotten egg smell in my hot water mean?
Often a reaction between the anode rod and certain water conditions. A different anode material can help; a plumber can confirm the cause.
Should I switch to tankless?
It can make sense if you want endless hot water or need the space, but it may require a larger gas line, new venting, or an electrical upgrade. Get a quote that includes those changes, not just the unit.
Can a leaking water heater cause damage elsewhere?
Yes. Water spreads across basement floors and into finished areas quickly. A drain pan piped to a floor drain helps where the heater sits above living space.
Related: emergency plumbing, leak detection, drain cleaning, burst and frozen pipes, water line replacement, sump pumps, sewer line repair, how calls work and the areas we cover.