(408) 978-3093

Tankless Water Heater Installation and Repair in San Jose, CA

Endless hot water from a unit the size of a suitcase. We size, vent and install gas and electric tankless water heaters for San Jose homes, repair and descale the ones you have, and replace units at the end of their life.

  • Google 4.9130+ reviews
  • Licensed C-36 · C-20 · ACSLB License #1101278
  • 1-year labor warranty24/7 service since 1986
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A smiling CPI Service plumber with a toolbox next to a CPI Service van in a San Jose driveway

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Tankless Water Heater Services

Residential and light commercial, all major brands.

  • Tankless water heater installation

    Sized to your home's peak demand, with the gas line, venting, condensate drain and electrical work a tankless unit needs.

  • Tankless water heater repair

    Error codes, ignition and flame failures, flow sensor problems, cold-water sandwiches and leaks diagnosed and fixed.

  • Descaling and maintenance

    Annual descaling flush, inlet filter cleaning, and burner, fan and vent checks to protect efficiency and the warranty.

  • Tankless replacement

    Failed or outdated units replaced, often reusing the existing venting and gas line when they still meet code.

  • Tank-to-tankless conversion

    Upgrading from a tank, including gas line upsizing and new venting through the wall or roof.

  • Recirculation systems

    Recirculation pumps and loops that bring hot water to distant fixtures faster and save water.

Signs Your Tankless Water Heater Needs Service

Tankless units are reliable, but scale and wear catch up with them.

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  • Error codes on the display

    Codes point to ignition, venting, flow or overheating problems; many trace back to scale.

  • Lukewarm or fluctuating temperature

    Scale on the heat exchanger, a dirty inlet filter or an undersized unit.

  • Bursts of cold water

    Some cold between hot is normal; long or frequent cold spells are not.

  • Low hot water flow

    Clogged inlet filters and scale restrict flow, especially with moderately hard South Bay water.

  • Unit won't fire

    Gas supply, igniter, flame rod or fan problems.

  • No descaling in over a year

    Most manufacturers call for regular flushing to keep the warranty valid.

Why Consider a Tankless Water Heater?

  • Endless hot water. It heats as you use it, so back-to-back showers don’t run it dry.
  • Space. A wall-mounted unit frees up the closet or garage floor a 50-gallon tank used.
  • Efficiency. No standby losses from keeping a tank hot all day.
  • Long life. Well-maintained units often last 15 to 20 years, longer than most tanks.

The trade-offs are a higher up-front cost, the need for regular descaling, and, for gas units, a gas line and venting sized for a high-input burner.

Tankless vs. Tank Water Heaters

Tankless Tank
Hot water supply Continuous, limited by flow rate Limited by tank size
Up-front cost in San Jose $1,800–$6,000+ $1,200–$2,000+
Typical life 15–20 years with maintenance 8–12 years
Space Wall-mounted Floor space for the tank
Maintenance Annual descaling Annual flush

For large households with high hot water demand, tankless is often the best fit. If running cost and future Air District rules matter most, also compare a heat pump water heater.

Maintenance You Can Do Yourself

  • Clean the cold water inlet filter every few months.
  • Keep the air intake and vent terminal clear of leaves, cobwebs and plants.
  • Watch for error codes and write them down for the technician.
  • Descale once a year if the unit has isolation valves, or let us handle it with your service plan.

Sources

Checked October 2026.

How Much Does a Tankless Water Heater Cost in San Jose?

A tankless water heater in San Jose typically costs $1,800 to $6,000 or more installed. Replacing an existing tankless unit sits at the low end; converting from a tank with new venting and a larger gas line sits at the high end.

Typical tankless water heater service prices in San Jose, installed, in US dollars. Checked October 2026.
ServiceTypical San Jose price (USD)
Tankless water heater, installed$1,800–$6,000+
Standard tank, for comparison$1,200–$2,000+
Heat pump water heater, for comparison$2,500–$6,000+
Flat-rate pricingTypically based on $150–$250 per hour, plus parts and drive time
Inspection feeWaived for service plan members$59

What affects the price

  • Gas line size. Many tank-to-tankless conversions need a larger gas line from the meter.
  • Venting. New stainless or PVC venting through a wall or roof.
  • Unit size and type. Higher flow rates and condensing models cost more.
  • Electrical. Gas units need an outlet; electric tankless units need large dedicated circuits.
  • Location. Moving the heater from a closet to an exterior wall adds piping.

Most repairs are quoted as a fixed price before we start. Ranges are typical for San Jose and the South Bay and don't include current specials.

Read the water heater installation cost guide →

How Our Tankless Services Work

  1. Assess your home

    We look at fixtures, household size, gas service, venting routes and electrical.

  2. Size the unit

    We size by peak flow, not guesswork, so showers stay hot when the dishwasher runs.

  3. Written price

    You get a written price covering the unit, gas, venting, permit and haul-away.

  4. Install

    Most installations take 4 to 8 hours, longer if the gas line or venting needs major work.

  5. Test and teach

    We test combustion, flow and temperature, and show you the controls and the isolation valves for descaling.

  6. Inspect and maintain

    We schedule the City inspection and can add annual descaling to a service plan.

Tankless Water Heaters in San Jose

Local conditions that matter for tankless units.

  • Hard water and scale

    Moderately hard South Bay water builds scale in heat exchangers. Annual descaling, or a scale-reduction filter, keeps units efficient.

  • The Air District rules

    The Bay Area Air District's zero-emission rule for new small tank heaters is set for 2027, with a delay to 2028 proposed; rules for gas tankless units are expected later. Ask us about the current status.

  • Permits

    Tankless installations need a City permit and inspection, covering gas piping, venting and the condensate drain.

  • Gas line capacity

    Older San Jose homes often have gas lines sized for a tank heater and furnace only; we check the load before quoting.

Neighborhoods we serve: Downtown San Jose · Willow Glen · East San Jose · South San Jose · Evergreen · Cambrian Park · West San Jose · Berryessa · North San Jose · Blossom Valley

Current Specials

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What Our Customers Say

Google 4.9 from 130+ reviews: read more →See photos of our work →

  • Great, reliable, and timely service at a reasonable price. I shopped around quite a bit before landing on CPI. Their rates were competitive, they responded promptly, and their plumber fixed a few issues quickly and without much fuss. I’ll definitely be calling them again the next time we have issues!

    Allan H.Google review

  • CPI did a great job on some minor plumbing work that I needed done. Their price was fair and scheduling was easy.

    Megan S.Yelp review

  • I have used CPI for many years and they are the best! Luis was my tech this time and he was excellent. Explained everything to me and did a great job.

    Bernadette S.Google review

Tankless Water Heater Service FAQs

How does a tankless water heater work?

When a hot tap opens, water flows through a heat exchanger warmed by a gas burner or electric elements and comes out hot, with no storage tank.

How much does a tankless water heater cost in San Jose?

Typically $1,800 to $6,000 or more installed, depending on the unit, the gas line and the venting.

How long does tankless installation take?

Usually 4 to 8 hours. Conversions that need a new gas line or venting can take longer.

How fast can you repair or replace a tankless unit?

Many repairs are done on the first visit. Replacements usually take a day or two, depending on parts and the model.

Do tankless water heaters need maintenance?

Yes. Annual descaling, inlet filter cleaning and a burner and vent check keep them efficient and are often required by the warranty.

What size tankless water heater do I need?

It depends on how many fixtures run at once and the incoming water temperature. A typical three-bathroom home may need about 9 to 11 gallons per minute; we size it for your home.

Can I descale a tankless water heater myself?

If it has isolation valves, yes: turn off power and gas, close the valves, and circulate a descaling solution such as white vinegar through the unit with a small pump for about an hour, then flush with fresh water and clean the inlet filter. Follow your manufacturer's instructions.

Helpful Guides

Serving San Jose and the South Bay

Our shop is at 2880 Aiello Dr in San Jose. We provide tankless water heater service across the city and nearby South Bay and Peninsula communities. See our full service area.

Content and prices reviewed October 2026.

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