
Tankless Water Heater Repair in Union, NH
Tankless water heater repair in Union, NH for units that flash a code, run lukewarm or quit halfway through a shower. Each suspect part is tested, then fixed at a price you agree first.
- Descaling through service valves
- Rinnai, Navien, Noritz, Rheem, Takagi
- Error history read first
Fault found first
The code, the stored history and each suspect part are tested before anything is ordered.
Price agreed in writing
Parts and labor go on a written quote, and nothing starts until you approve it.
Licensed local techs
Repairs by licensed technicians who work in your part of town.
Tankless units only
One specialty: gas and electric tankless heaters that stopped doing their job.

Tankless Units in Union Homes
Basement units are standard in Union. A buried vent after a storm and a condensate pump that quits are two of the most common no-hot-water calls.
What we run into in Union
- Basement units. Basement installs are common, often condensing units whose acidic condensate runs to a floor drain or a small pump.
- Snow on vents. Snow drifting against a sidewall vent will stop a unit cold with a venting code until the termination is cleared.
- Freeze damage. A hard freeze can split the pipes feeding a unit. Its built-in freeze protection only works while the unit still has power and gas.
Repair visits reach all of Union: 03887.
Call (380) 273-8196Tankless Problems We Fix Around Union
The list below covers what we find on most visits for tankless water heater repair in Union, NH, from ignition codes to drips under the cabinet.

Code 11, E003 or 111
A unit that clicks without lighting has an ignition, gas or venting fault, and each is checked in turn.

Drip from the cabinet
Drips come from service valves, fittings, the relief valve, the condensate line or the heat exchanger itself.

Code 10 or E110
Venting codes mean the unit can't breathe: a blocked termination, a nest, snow or a vent run that's too long.
Cold at one tap only
Usually a mixing valve or a cold-water crossover at that fixture, not the heater.
LC code on a Rinnai
The unit is reporting scale buildup. It needs a descale, and soon.
Frozen after a cold night
Lines feeding the unit froze, or freeze protection lost power.
Can't tell which one you have? Read us the display and describe the water, and the likely fault comes back on the call.

Fix It or Retire It? Deciding in Union
Igniters, flame rods, sensors, fans, gas valves and boards are worth replacing on almost any unit. The hard call is a leaking or cracked heat exchanger on an older unit, because that part can approach the price of new.
Not sure which side of the line you are on? Call (380) 273-8196 with the brand, the age on the label and the code. You will hear whether a repair makes sense before anyone comes out.
Call (380) 273-8196Estimated Repair Costs in Union
Most tankless water heater repair in Union, NH lands between an estimated $150 and $800 for parts and labor. A heat exchanger is the outlier, estimated at $1,000 to $2,500.
Diagnosis & code check
- Model and serial noted for warranty
- Stored error history read
- Flow, filter and venting checked
Repairs & descaling
- Igniter, flame rod or sensor replaced
- Isolation valves added for flushing
- Inlet filter screen cleaned
Heat exchanger & major parts
- Fan motor or blower replaced
- Warranty part claimed where it applies
- Leaking heat exchanger replaced
Need Tankless Water Heater Repair in Union, NH? Call Today
A code that keeps returning after a reset is the unit asking for a proper look.
Union Homes by the Numbers
With electricity the main heating fuel in Union (about 0% of homes), many tankless units here are electric, and their faults are elements, breakers and sensors rather than burners. The median home here dates from 2003, so tankless units are a mix of original-era installs and newer replacements, and an older unit that has never been descaled is a frequent find. Owners live in about 100% of Union homes (single-family about 87%), so the person who calls is usually the person who decides.
Union covers about 0.3 square miles and holds roughly 354 residents, around 1,142 per square mile: spread out, with mostly detached homes on larger lots and longer runs between fixtures and the street. It is number 50 by population of the 58 New Hampshire places on our service list.
Source: U.S. Census Bureau, American Community Survey 2019-2023 5-year estimates for Union, NH.
Union Weather and Water Temperature
Winter here is long: roughly 140 nights a year drop to freezing or below, and the lowest reading in the past three years was about -23°F. Condensate traps, supply stubs in unheated spaces and vent caps are the usual victims, so a tankless unit in Union deserves a close look before the cold sets in.
In Union the cold tap is probably around 36°F in winter and 59°F in summer, based on a January average of 23°F, a July average of 70°F and a yearly average of 48°F. Heating that water to 120°F takes a rise of about 84°F in winter, so a 199,000 BTU gas unit at 90% efficiency tops out near 4.3 gallons per minute, compared with roughly 5.9 in summer when the rise is only about 61°F.
For comparison, a shower draws roughly 2 gallons per minute, so two at once plus the dishwasher can pass the winter figure. If the water goes lukewarm only when several taps run, the unit is likely maxed out; if it goes lukewarm at one tap, the cause is more often scale, a flow sensor or the flame.
Weather: NASA POWER daily temperatures, 2021-2023, for the grid cell around Union, NH, corrected to the town's elevation (USGS). Tap-water temperatures and flow rates are estimates, not measurements.
Where We Go in Union
Repair visits reach all of Union: 03887.
- 03887
Nearby Cities We Serve
Tankless Water Heater Repair in Union, NH: FAQs

Question not covered here?
Call and ask. Someone who repairs tankless units answers, and the phone quote is free.
Call (380) 273-8196How much does tankless water heater repair in Union, NH cost?
Most repairs cost an estimated $150 to $800, depending on the part. Descaling alone is estimated at $150 to $350, and a heat exchanger at $1,000 to $2,500. Freeze repairs depend on what split, and are priced once the damage is seen.
Why is my tankless water heater not turning on?
First confirm power and gas. If both are there, the usual causes are low flow, a dirty inlet filter, a bad flow sensor or an ignition fault. In Union, after a hard freeze also check whether the condensate line has frozen, since many condensing models shut down when it blocks.
Is there a reset button on a tankless water heater?
Most units reset by switching power off and on, or through the controller. A reset clears the code, not the cause; ignition and exhaust codes that return need a repair visit.
How often should a tankless water heater be flushed?
Once a year for most homes, and twice a year on very hard water. Soft-water homes can stretch it, but never skip it for years. In Union, do the flush in autumn, before the freezing nights (about 140 a year) begin, so nobody is working the service valves in a frozen garage.

Book Your Union Repair Visit
Call (380) 273-8196. Nothing is repaired until you have approved the written quote.