What changes when you go tankless
A tank heater keeps a reserve of hot water ready. A tankless unit heats water only as it flows, using a powerful burner or element that turns on when a tap opens. That is why it never runs out during a long shower, and also why it can need far more gas at once than the tank it replaces.
In many La Mirada garages the original gas line was sized for a tank heater, a furnace and perhaps a dryer and range. A whole-house gas tankless unit may need a larger line from the meter, and sometimes a meter upgrade arranged with SoCalGas. Venting usually changes too, from a metal flue to a dedicated vent system.
Tank versus tankless
Tank
- Lower upfront cost and simpler installation.
- Works with the existing gas line and flue in most cases.
- Hot water limited to the tank's capacity.
- Loses some heat while standing.
- Tank eventually corrodes and is replaced.
Tankless
- Continuous hot water within its flow rating.
- Wall-mounted, freeing floor space.
- Often needs a larger gas line and new venting.
- Needs regular descaling in hard water.
- Many parts are serviceable rather than replaced as a whole.
How a conversion is usually planned
- Size for your household.Count fixtures that may run at once, such as two showers and a washer, and choose a unit whose flow rating covers them.
- Check the gas supply.The plumber totals the appliances on the line and checks pipe size and length from the meter. An undersized line can starve the heater or other appliances.
- Plan the venting.Condensing units typically vent through plastic pipe and need a condensate drain; non-condensing units use specific metal venting. Clearances from windows and doors apply.
- Add service valves.Isolation valves let the unit be descaled without draining the whole system.
- Permit and inspection.Gas, venting and water heater work commonly needs a permit. Check with the city.
What drives the cost of a conversion
| Factor | Why it matters |
|---|---|
| Gas line upsizing | A new or larger line from the meter is often the biggest variable. |
| Venting route | Distance and wall or roof penetrations affect labor and materials. |
| Condensate disposal | Condensing units need a drain path, sometimes with a neutralizer. |
| Electrical | Most gas tankless units need a nearby outlet; electric units need large dedicated circuits. |
| Location | Moving the heater from the original spot adds water and gas piping. |
Questions to ask before switching
- What flow rate do we need, and which unit size covers it?
- Is my gas line large enough, and will SoCalGas need to change the meter?
- Where will the vent and condensate drain run?
- How often should it be descaled with our water?
- Can you price a comparable tank replacement for comparison?
Common questions
Does tankless give instant hot water?
No. Hot water still has to travel from the heater to the tap. A recirculation system can shorten the wait if that matters to you.
Does a tankless heater need seismic strapping?
Wall-mounted units are secured to the wall rather than strapped like a tank. Ask your installer how the unit and its connections are supported.
Can I install a tankless unit outside?
Many models are rated for outdoor installation, which can simplify venting. Ask about placement rules and protecting the piping.
General information for La Mirada, not a quote or professional advice. In an emergency, call 911.