A tankless, or on-demand, water heater heats water only when a tap is open. There is no tank holding gallons of hot water, so the unit can be compact and hot water does not run out the way a tank can. The trade-off is that the installation asks more of the house than a like-for-like tank swap.
This guide explains what the job involves and what to check before you commit. When you are ready, call (714) 750-8637 and a licensed plumber can walk through the plan for your house.
What changes when you go tankless
A tank heater heats a reservoir and keeps it warm. A tankless unit heats water on the way through, using a much stronger burner or heating element. That strength is the reason the supporting pieces matter.
For a gas model, the gas line may need to carry more fuel than the old tank required. For an electric model, the electrical panel may need capacity and a dedicated circuit. Either way, the plumber checks these before quoting.
The unit is usually mounted on a wall, which can free floor space. Where it goes depends on venting, access and the pipe routes already in place.
Gas or electric tankless: what each asks of the house
Both types deliver on-demand hot water. They ask different things from the building.
| Question | Gas tankless | Electric tankless |
|---|---|---|
| What supports it | A gas line sized for the unit | Panel capacity and a dedicated circuit |
| Venting | Needs a proper exhaust path | No combustion venting |
| Typical install work | Gas, vent and water piping | Electrical work and water piping |
| Biggest planning risk | An undersized gas line | Not enough spare panel capacity |
| Good fit | Homes with existing gas service | Homes with strong electrical service and no gas |
Power and gas needs are sized to the specific unit and the number of fixtures it serves. A plumber confirms both before you buy.
How a tankless installation unfolds
A careful job follows a clear order, and the plan comes before the equipment.
- 01
Survey the house
The plumber checks gas or panel capacity, venting options, the mounting location and your hot water habits.
- 02
Size the unit
The heater is chosen to match the fixtures that might run at the same time.
- 03
Remove the old tank and set the new unit
The tank is drained and removed, and the wall mount, valves and connections are put in.
- 04
Test and walk you through it
The unit is started, checked for leaks and temperature, and you are shown the controls and the service valves.
Hard water, permits and Placentia homes
Golden State Water's 2026 report for the Placentia-Yorba Linda system gives an average hardness of 11.0 grains per gallon, with a range of about 3.9 to 17.5. That is well into the range where scale builds up inside a heat exchanger. A tankless unit has narrow passages, so scale matters, and a yearly flush of the unit is part of owning one. Water softening is covered on the water softener installation page.
Venting, gas and water connections for a tankless unit are set by the California Plumbing Code, Title 24, Part 5, which rests on the Uniform Plumbing Code (UPC).
The City of Placentia Building & Safety Division lists water heaters and gas outlets among the plumbing permit items on its application. Ask the division at (714) 993-8124 whether your installation needs a permit. Check your bill to see whether Golden State Water or Yorba Linda Water District serves your address.
What to do before you buy: questions to settle
- Is the gas line or panel large enough? This is the most common surprise, and it is checked before a unit is chosen.
- Where will it vent or mount? The location shapes the whole job and can change the price.
- Will you add a water softener? With hard water, protecting the heat exchanger is part of the plan.
- How many fixtures run at once? Two showers and a dishwasher together decide the size of unit you need.
- Is the old tank braced? California Health and Safety Code 19211 requires bracing for tank heaters, so it matters if you keep one.
Installation, replacement or repair: picking the right service
If you are putting a tankless unit where a tank used to be, the job is tankless water heater installation and the plumber handles gas, venting, water and the connection work together.
If your current heater has failed and you want to compare a tank with an on-demand unit, water heater replacement covers the choices side by side.
If the unit is working but something is wrong, a visit under water heater repair can fix a part before a full swap becomes necessary.
Tankless installation questions in Placentia
It heats continuously while water flows, but each unit has a limit on how much it can heat at once. Size the unit to the fixtures that run together.
The city permit application lists water heaters as a plumbing permit item. Ask the Building & Safety Division at (714) 993-8124 about your job.
Scale can build up inside the unit, and Golden State Water's 2026 report shows an average of 11.0 grains per gallon. Regular flushing and sometimes a softener keep it healthy.
Not always. These units can need more gas flow than a tank, so the plumber checks the line size before you buy.
If your heater has failed, call the 24/7 line at (714) 750-8637. Same-day appointments are offered when available.