Advanced Combustion · Scenario 05

Water heater ignition,
tankless & tank.

Ceramic water heater igniters for tankless (on-demand) and tank-type gas water heaters. Tankless units can fire 30–50 times per day, making Si₃N₄ the preferred specification for high-cycle gas water heater igniter applications.

On-demand

Tankless Duty

100K+

Cycle Life

3 sec

Heat-Up

UL/CE

Certified

Request Free Samples →View BLK Specs →

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★ Tankless water heater duty

Why on-demand heaters demand Si₃N₄

30–50

Ignitions/day in busy household

5+ yr

Tankless field life, BLK

1–2 yr

Al₂O₃ life in same duty

Sealed

Element — condensate-proof

Certifications & Standards

ISO 9001IATF 16949CERoHS · REACHUL Recognized

500M+

Households globally using gas water heaters — largest single gas appliance category

30–50

Daily ignitions in a tankless water heater — 10–30× a tank-type heater or gas furnace

5yr+

Typical BLK Si₃N₄ life in tankless service vs 1–2yr for Al₂O₃

48h

Sample dispatch — Rinnai, Navien, Noritz, Bosch compatibility on file

01 · The Application

Tankless heaters demand ignition on every draw.

🚿

BLK igniter in tankless water heater burner

Replace with product photo

Tankless (on-demand) water heaters fire the burner on every hot water draw — up to 50 times per day in a busy household. That cycle frequency is 10–30× higher than that of a tank-type water heater and 5–10× higher than that of a gas furnace. Combined with condensate exposure from the previous cycle, this is one of the toughest residential applications for a water heater igniter.

The CN-300 series supports water heater igniter replacement programs for Rinnai, Navien, Noritz, Bosch, and Vaillant platform geometries. The sealed Si₃N₄ element resists exposure to condensate and helps prevent moisture ingress.

Technical Requirements

Daily cycles30–50 per household

EnvironmentCondensate-exposed

Voltage120V (NA) · 230V (EU)

CertificationsUL Recognized · CE · CGA

02 · Material Selection

Si₃N₄ vs Al₂O₃ for

tankless water heater duty

★ Recommended

Silicon Nitride (Si₃N₄)

BLK · 100K+ cycles · 5-year tankless life

✓
5+ year field life in tankless 30–50 cycle/day service
✓
Condensate-resistant — sealed element, no moisture ingress cracking
✓
3-second heat-up — fast on-demand response for user experience
✓
CGA certified variant for Canadian market
✓
Rinnai, Navien, Noritz, Bosch compatibility data on file

View Full Specs →

Also Available

Alumina (Al₂O₃)

Standard duty · not recommended for tankless

→
Lower initial cost — 20–30% less per igniter
→
Adequate for tank-type heaters — 3–8 cycles/day only
⚠
1–2 year life in tankless duty — condensate + high cycle kills Al₂O₃ fast
⚠
Not recommended for on-demand/tankless applications

Tankless OEM compatibility program

Verified fit for major
tankless water heater OEM platforms.

Request Free Samples →Talk to an Engineer

Compatibility data on file

Rinnai: V75i, V94i dimensions
Navien: NPE series
Noritz: EZ98 platform
Bosch: WH27/WH36
CGA: Canadian certification variant available

03 · Tankless Igniter Failure Modes

Why high-cycle water heater igniters fail.

Tankless water heaters combine high ignition frequency with condensate exposure — the combination that most rapidly destroys Al₂O₃.

Condensate cracking on cold start

Condensing heaters accumulate moisture in the combustion chamber between cycles. Cold-start ignition into a wet chamber causes rapid thermal shock — the primary failure mode for Al₂O₃ in tankless service.

Si₃N₄ fix → sealed element, impervious to moisture. Condensate presence does not affect thermal shock resistance.

High-frequency thermal fatigue

30–50 ignitions per day creates more thermal fatigue cycles per year than many industrial applications. Si₃N₄ fracture toughness (6–7 MPa·m½) vs Al₂O₃ (3–4 MPa·m½) is the key differentiator.

Si₃N₄ fix → 4–6× higher fracture toughness. Thermal fatigue crack growth rate is 5–10× slower.

Grease and scale contamination

Scale, dust, and combustion by-products can accumulate over time on igniter surfaces in small utility rooms with poor ventilation, necessitating periodic inspection or cleaning.

Si₃N₄ fix → higher surface hardness resists scale adhesion. Periodic cleaning with damp cloth is safe.

04 · Engineering FAQ

Questions from water heater engineers.

Does BLK work in condensing tankless?

Yes — sealed Si₃N₄ element is unaffected by condensate. Tested per IEC 60335-1 moisture ingress standards.

What OEM platforms do you have compatibility for?

Rinnai V75i/V94i, Navien NPE series, Noritz EZ98, Bosch WH27/WH36, Vaillant ecoTEC plus. Send your current part number for confirmation.

Connector and harness options?

Standard: bare element with stripped leads. OEM connector assemblies (Molex, AMP, flying leads with silicone sleeve) available as factory-fitted option.

Can CN-300 be used as a water heater igniter replacement?

Yes. CN-300 is available as a replacement gas water heater ignition for compatible tankless or tank-type platforms. Send us your part number, voltage, and mounting size. Also, please include the connector type and lead wire.

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