Data checked August 6, 2026 · source: US Bureau of Labor Statistics

How much does a tankless water heater cost to install?

The unit is the cheap part. What decides your quote is whether your gas line and your vent can handle it — and on a tank replacement, usually they cannot.

Where the money actually goes

This is the same quote, taken apart. Every line is a real price from a real listing or a published fee schedule, not a number we made up.

The low column assumes a straightforward job with the cheapest listed equipment; the high column assumes the full parts list, the top of the labour range and the most expensive permit jurisdiction we measured. Most real quotes land in the middle.

What the equipment costs

Source: SupplyHouse tankless category listings, checked August 6, 2026.

Specific products, with the price we saw

Not a recommendation and not an affiliate link. These are the listings we checked on August 6, 2026, so you can see whether the equipment line on your quote is close to retail.

Retail prices move. If one of these is wrong now, tell us and we will fix it with the date.

Parts list

What this job costs in 49 US metro areas

Materials cost roughly the same everywhere. Labour does not. The wage column is US government data; the labour column is that wage run through our published multiplier; the total applies it to the job above. San Jose-Sunnyvale-Santa Clara comes out 14% higher than Tampa-St. Petersburg-Clearwater on the same work.

Wages: BLS OEWS May 2025, SOC 47-2152 — public domain. Metros where BLS suppressed the figure are left out rather than estimated. Totals are FieldPricing calculations from the parts and hours on this page — they are not quotes and no contractor has agreed to them.

What did you actually pay?

Everything above this line is arithmetic on public data. It is honest, and it is not the same thing as a real invoice. If you have had this work done, the number on your invoice is worth more to the next reader than anything we can calculate.

What did you pay in total? Just the number is fine. $1,850, or "about 2 grand". Where? City and state. We publish this; it is the whole point.

When? Month and year is enough. What did it cover? Equipment included? Permit? Old unit hauled away? Anything unusual? This is the part that makes your number useful to somebody else. Email — optional Only used if we need to ask you one question before publishing. Never shown, never sold, never mailed to.

Website

Send it in

No account, no login, no newsletter. A person reads every submission before it appears, so it will not show up instantly. If we cannot make sense of one, we leave it out rather than guess — and if you would rather just email it, that works too.

What actually moves the price

Your gas line is probably too small

A tank burns 30,000–50,000 BTU an hour. A whole-house tankless burns 120,000–200,000. Tanks commonly run on a 1/2 inch line; tankless generally needs 3/4 inch minimum, sometimes 1 inch from the meter. Upsizing is $400–$1,500, and it is the most common reason a tankless quote comes in far above the unit price.

Your old vent cannot be reused

Condensing tankless units are Category IV — positive pressure, condensate rated. Type B vent and masonry chimneys are prohibited. That means a new penetration through a wall or roof on almost every tank retrofit.

Electric means a panel conversation

A Stiebel Eltron Tempra 24 Plus needs a 150A service minimum; the Tempra 29 needs 200A; the Tempra 36 needs 300A. If your panel is 100A, the panel upgrade ($1,300–$3,000) costs more than the heater.

Relocating it changes the job

Same-location gas condensing runs $2,700–$4,200. Move it and you are at $3,500–$6,000. Put gas where there is none and it is $4,500–$8,000.

New construction is 30–40% cheaper

Because the gas line, the vent path and the circuit get planned in rather than retrofitted. This is a retrofit penalty, not a tankless penalty.

Code requirements that cost money

These are the things an inspector will look for, and each one is a line on the invoice that a homeowner often reads as padding. Mostly it is not.

• Gas sizing — Must be sized for the full BTU demand of every connected appliance, with 5–7 inches water column at the inlet (IRC G2412, Table G2413.4(1)). Source.
• Category IV venting — Condensing units need listed positive-pressure, condensate-rated vent. Type B and masonry chimneys are prohibited (IRC G2427). Source.
• T&P relief valve — Required even though there is no storage tank (IRC P2803). Source.
• Expansion tank — Required on closed systems — pressure reducing valve, meter check valve or backflow preventer present. Must be ASME stamped (IRC P2903.4). Source.
• Permit is not optional — IRC P2801.1. Gas, vent and electrical are separate trade inspections. Source.

Code citations are to the California Plumbing and Mechanical Codes unless noted, because California publishes its handouts openly. Your jurisdiction adopts its own version of the model code — check locally before relying on any of this.

What we could not verify

We publish this list because a cost page that never admits a gap is not telling you the truth.

• Expansion tank part price — the requirement is confirmed in code, but we could not tie it to a retailer SKU.
• Black steel gas pipe per-length retail price — SupplyHouse lists the sizes but served no price. The installed per-foot figures above are sourced; the raw pipe is not.
• Navien unit prices — SupplyHouse does not carry the brand and we found no other retailer that served a price to us.

How we got these numbers

• Wages — BLS Occupational Employment and Wage Statistics, May 2025, SOC 47-2152 (Plumbers, Pipefitters, and Steamfitters), pulled through the BLS public API. US federal data, public domain.
• Billed rate — wage × 1.3 labour burden × 1.70–2.45 overhead and profit, so 2.21×–3.19× the wage. Our assumption, published in full on the methodology page so you can disagree with it.
• Equipment and parts — retailer and supply-house listings, each linked above, checked 2026-08-06.
• Labour hours — HVAC Base — tankless water heater cost · Hot Water Guys — cost to replace a gas water heater with tankless.
• Permit fees — Permitio — water heater permit California.
• Disposal — Dropcurb — water heater removal cost.

We do not use RSMeans or Craftsman cost data. Their licences forbid building a database from them, so every number here traces to a public source or a public listing you can open yourself.

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