Combi boiler service on Long Island. Navien, Rinnai, Bosch and Noritz repair, descaling for hard water, combi installation.
Most combi boiler repairs total $189–$500, including the flat $189 service call that covers the first hour of labor; parts are billed separately. An annual descale and flush runs $250–$450. A new combi boiler installed costs $9,000–$14,000, with free estimates.
Combi and tankless units heat water through narrow stainless or copper passages, and the island's hard water coats those passages with scale season by season. The symptoms follow a predictable arc: hot water that starts strong and fades, temperature swings mid-shower, error codes for outlet temperature, and eventually a heat exchanger running hot enough to shorten its own life. Homeowners in Massapequa Park and across the South Shore see it fastest because usage is high and the water is no kinder there than anywhere else on the island. An annual descale and flush — circulating cleaning solution through the exchanger — is the single most valuable service these units get, and skipping it is the leading reason combi boilers die young here.
We service the brands that hang on Long Island walls: Navien above all — it is the unit we see most in Mount Sinai and everywhere else — along with Rinnai, Bosch and Noritz. We stock the common failure parts for these lines rather than ordering and returning.
A combi boiler replaces both the boiler and the water heater in one wall-hung unit, which frees basement floor space and suits households where domestic hot water demand is moderate. Installed properly on Long Island, that means an isolation valve kit for future descaling, a water filter or scale treatment ahead of the unit, correct gas line sizing — these units draw far more gas at full fire than a tank heater ever did — and condensate neutralization. We include all of it in the $9,000–$14,000 installed price rather than treating maintenance access as an option. Homes in Greenlawn converting from an aging boiler-plus-tank setup are typical candidates, and when a big-family hot water load argues for an indirect tank instead, we say so during the free estimate. Our boiler installation page covers the tank-based alternative in detail.
Installation day runs long but predictable: old equipment out, the wall unit hung and piped, gas capacity verified, venting and condensate run, and the system commissioned against the manufacturer's combustion targets before we leave. The settings are recorded in writing, which makes every future service visit faster. Ask about annual service while we are there — a combi maintained from year one on this water simply lasts longer.
Combi units carry the water-heating load too, and the ENERGY STAR water heater directory is a good primer on why descaling matters so much with Long Island’s hard water.
| Job | Typical Long Island Price | Notes |
|---|---|---|
| Service call | $189 | Diagnosis plus the first hour of labor |
| Descale and flush | $250 – $450 | Annual; local hard water demands it; isolation valves required |
| Ignition or flame sensor repair | $189 – $400 | Total, including the service call |
| Flow sensor or check valve repair | $250 – $500 | Common cause of lukewarm hot water |
| Combi boiler, installed | $9,000 – $14,000 | Navien, Rinnai, Bosch or Noritz, with valve kit and treatment |
Ranges reflect typical Nassau and Suffolk pricing. Your exact price is quoted upfront after diagnosis. Prices as of August 2026.
Yes, Navien is the combi brand we see most across both counties, and we stock the common parts: ignitors, flame rods, flow sensors and check valves. Bring the error code from the display when you call and we can usually arrive with the likely part on the truck.
Annually. Our water is hard enough that scale measurably narrows the heat exchanger passages within a year or two of heavy use. The flush costs $250–$450 and protects an exchanger that costs many times that to replace.
The classic cause is scale on the flow sensor or heat exchanger making the unit misjudge how much water it is heating. Failing diverter valves and undersized gas supply produce similar swings. It is diagnosable in one visit and usually repairable the same day.
For one- and two-bathroom homes with moderate hot water use, yes: high efficiency, small footprint, one appliance instead of two. For large families running simultaneous showers and laundry, a boiler with an indirect tank usually serves better. We recommend based on your usage, not on what we prefer to sell.
$9,000–$14,000 on Long Island, including isolation valves for future service, scale treatment, condensate handling and permit. Estimates are free, and we quote a tank-based alternative alongside it when your usage suggests one.
Each brand has its own code table, but the frequent flyers point to ignition failure, flow problems, blocked condensate or exhaust, and outlet temperature faults from scale. Note the code and how often it appears; repeated codes after resets mean the underlying fault is progressing, not clearing.
Heat-loss-sized boiler installs.
Tank, tankless and indirect units.
Permitted, pressure-tested gas work.
Everything we repair, install and maintain across Long Island.
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