
Tankless Water Heater Repair in Union, NH
Tankless water heater repair in Union, NH, step by step: the fault log is pulled, gas pressure is checked while the burner fires, flow and the inlet screen are inspected, and only the bad part gets changed.
- Fault log checked first
- You approve the price before work
- Descaling through isolation valves
Diagnosis before parts
We confirm what failed by testing it, so you never pay for a guess or a part that wasn't needed.
You approve the cost
The repair and its price are spelled out on paper, and work begins only after you say yes.
Technicians near you
The person at your door works your area and repairs on-demand heaters week in, week out.
Only tankless repair
No tank heaters, no remodels. Gas and electric on-demand units are the whole job.

What Union Does to a Tankless Heater
Basements are where most Union tankless heaters live, often condensing models vented out the side wall. Every winter brings snow against that vent and condensate lines that clog.
Local factors in Union
- Basement heaters. With a basement heater, a plugged condensate trap or a dead pump can shut things down with a code well before any puddle shows up.
- Snow-blocked vents. After a heavy storm, one of the first suspects for lost hot water is an intake or exhaust pipe sitting under fresh snow.
- Winter freezes. Overnight power outages during cold snaps are what cause damage locally; after each hard freeze we repair frozen lines and cracked fittings beneath heaters.
All Union ZIP codes (03887) fall within our coverage.
Call (888) 987-0567Tankless Trouble We See in Union
Nearly every request for tankless water heater repair in Union, NH starts with a symptom on this list and finishes with a single replaced component or a flush.

Clicks, but no flame
A no-ignition code points to low gas pressure, a sooted flame rod, a tired igniter or a vent obstruction, and we test each.

Puddle below the heater
Where the water comes from decides the bill: a valve or a joint is minor, a failed exchanger is not.

Air supply or exhaust fault
The burner shuts down on an air or exhaust fault to keep you safe. We clear and inspect both intake and exhaust.
Only one faucet runs cold
Typically a worn mixing cartridge or a crossover at that fixture, rather than the heater itself.
Rinnai showing LC
That's the scale warning. The exchanger is due for a descale, and it shouldn't wait long.
No hot water after a freeze
A supply line froze, or the heater lost electricity and its freeze protection with it.
Not sure which of these it is? Describe the symptoms on the phone and we'll tell you what it most likely is.

Keep It Running or Replace It in Union?
For the vast majority of faults, repair is the answer. The math only tips toward a new heater when an out-of-warranty exchanger has failed, or when an electric model is close to the end of its shorter service life.
When you call (888) 987-0567, mention the make, the approximate age and what the heater is doing. If a repair isn't worth the money, we'll say so plainly.
Call (888) 987-0567What a Tankless Fix Costs in Union
Plan on an estimated $150–$800 for most tankless water heater repair in Union, NH; the make, the part and how easy the heater is to reach all move the number. A new heat exchanger is estimated separately at $1,000–$2,500.
Diagnostic visit
- Label age and serial recorded
- Fault codes and log reviewed
- Inlet screen, flow rate and vent inspected
Component repair & descale
- Igniter, flame sensor or thermistor changed
- Service valves fitted for future flushes
- Inlet screen rinsed clean
Exchanger & major components
- Blower motor replaced
- Maker's parts warranty checked first
- Cracked or leaking exchanger swapped
Call Today for Tankless Water Heater Repair in Union, NH
If the same code returns every time you reset, the heater is telling you it needs a real diagnosis.
Housing in Union at a Glance
Union is mainly an electric-heat market, at about 0% of homes, which makes an electric tankless model a likely find; those units draw heavy current, so a fault often shows up at the breaker, an element or a temperature sensor. Homes here have a median build year of 2003, so many tankless units here took the place of an original tank heater, and units that have gone years without a descaling flush are a frequent source of trouble. Union has an owner-occupancy rate near 100% and about 87% single-family housing, so most tankless repair calls likely come straight from the homeowner.
Union spreads about 354 residents across roughly 0.3 square miles, close to 1,142 people per square mile, which makes it fairly spread out, mostly detached houses on bigger lots, where a tankless unit is commonly mounted in a garage or on an outside wall. Our New Hampshire coverage list has 58 communities, and this one is number 50 among them by population.
Figures: 2019-2023 five-year American Community Survey estimates for Union, NH, published by the Census Bureau.
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.
ZIP Codes We Cover in Union
All Union ZIP codes (03887) fall within our coverage.
- 03887
Close-by cities
Tankless Water Heater Repair in Union, NH: FAQs

Still unsure?
Phone us and describe what the unit is doing. A tankless tech can usually narrow it down while you are on the line.
Call (888) 987-0567What does tankless water heater repair in Union, NH cost?
Depending on which part failed, most repairs run an estimated $150–$800. Expect an estimated $150–$350 for a stand-alone descale and an estimated $1,000–$2,500 for a replacement heat exchanger. Freeze damage is priced once we see what cracked, since no two splits are alike.
Why won't my tankless water heater turn on?
First make sure the outlet has power and the gas valve is open. If both check out, look at low flow, a plugged inlet screen, a bad flow sensor or trouble in the ignition circuit. In Union, after a hard freeze also check whether the condensate line has frozen, since many condensing models shut down when it blocks.
Do tankless water heaters have a reset button?
Usually by power: turn the heater off, wait a moment, turn it back on. That clears the code, but if it returns, a component needs attention.
How often does a tankless water heater need flushing?
Most manufacturers recommend once a year, or every six months where the water is very hard. Soft-water homes can go longer, but years without a flush lead to scale faults. 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.

Restore Hot Water in Union
At (888) 987-0567 you reach people who deal with on-demand heaters all day. Tell us what's happening and choose a time.