The decision is about the whole installation
It is easy to compare water heaters on the unit alone, but the installation often decides the outcome. A replacement tank of the same type and fuel usually connects to the existing gas line, vent and water lines with modest changes. Switching to tankless can involve a larger gas line, a different kind of vent, a new electrical outlet and new mounting location.
In older Fullerton homes the gas piping was sized for the appliances of its day. A plumber should check whether the line can deliver what a tankless unit needs while the furnace, range and dryer are also running.
Side by side
Tank water heater
- Stores heated water, so supply is limited by tank size and recovery
- Usually the simpler swap when replacing a tank
- Needs seismic strapping and takes floor space
- Hard water builds sediment that can be flushed
- Standby heat loss keeps the tank warm around the clock
Tankless water heater
- Heats water on demand, so it does not run out in the same way
- May need gas line, venting and electrical changes
- Wall mounted, freeing floor space
- Hard water builds scale inside the heat exchanger and needs descaling
- Flow rate limits how many fixtures run hot at once
What drives the installed cost
| Factor | Why it matters |
|---|---|
| Gas line size and length | A tankless unit may need a larger line from the meter |
| Venting | Tankless units use specific vent materials and routes; old vents may not be reusable |
| Location | Moving the heater means new water, gas and vent runs |
| Electrical | Most gas tankless units need an outlet; electric units need substantial capacity |
| Water treatment | Some installers recommend a softener or scale filter with tankless in hard-water areas |
| Permit and inspection | Check with the city on what applies to your job |
Quick guide
- IfYour current tank works for your household and you want the simplest replacementThenA like-for-like tank is usually the shortest path.
- IfYou regularly run out of hot water with back-to-back showersThenCompare a larger tank with a properly sized tankless unit.
- IfGarage or closet space is tightThenTankless frees floor area, if the gas line and venting can be arranged.
- IfYou do not want routine maintenanceThenFactor in that tankless units need periodic descaling with hard water.
Information to gather before getting quotes
- Number of bathrooms and people in the house
- Photos of the current heater, its label, the vent and the gas connection
- Where the gas meter is relative to the heater
- Whether there is an outlet near the heater location
- Any history of running out of hot water
Questions that separate good quotes from vague ones
- Did you size the gas line for this unit, and does it need upsizing?
- What venting will be used, and where will it terminate?
- What maintenance does this unit need with our water, and how often?
- Does the quote include strapping, permits, haul-away and any electrical work?
Common questions
Will tankless give me unlimited hot water?
It will not run out like a tank, but it can only heat so many gallons per minute. Running several showers and appliances at once may exceed its capacity.
Does a tankless unit need seismic strapping?
Wall-mounted tankless units are fastened to the wall per the manufacturer's instructions. The seismic strapping requirement is aimed at storage tanks; ask your installer what applies.
Is a hybrid heat pump water heater an option?
It can be. Heat pump models need space, airflow and an electrical circuit. Ask a licensed plumber whether your location suits one.
General information for Golden Hills, not a quote or professional advice. In an emergency, call 911.