A gas job with a water heater attached
A tankless installation is a gas and venting job with a water heater attached. Get the BTU load and the pipe sizing right and the unit performs as advertised for fifteen years. Get them wrong and no amount of adjusting the temperature setting will fix it, because the appliance is being starved.
Sizing on flow rate and temperature rise, not gallons
A tank is sized in gallons. A tankless unit is sized on how many gallons per minute it can raise by how many degrees, and both halves matter.
- Charlotte's incoming water sets the rise. Roughly the high 50s to high 60s Fahrenheit through the year and colder in winter, so delivering 120°F means a rise of 55 to 65 degrees in the cold months.
- Headline flow rates are quoted at a 35 degree rise. A unit rated for a big flow at that rise will not deliver anything like its number here in January.
- Then we add up what you run at once. A shower is roughly 2 to 2.5 gpm, a kitchen tap around 1.5, a washing machine around 2.
- Two showers plus a tap is a different appliance. We do that calculation with you rather than quoting a model number.
The gas line, which is where most quotes go wrong
Your existing tank draws around 40,000 BTU per hour. A whole-house tankless draws 150,000 to 199,000, which is a four to five times increase in demand on the same pipe.
- Four things decide whether the line copes. Its diameter, its total length from the meter, and everything else on it: the furnace, the range, the dryer, a fireplace, a pool heater.
- An adequate line today can be badly undersized tomorrow. The symptom is a unit that ignites, runs, then cannot hold temperature as the burner ramps up.
- We give you the number before the work. Sometimes the existing line is fine. Sometimes it means a new run from the meter, and that is the single biggest variable in the quote.
- Where the meter is the constraint, Piedmont has to be involved. They are the only residential gas provider here.
Venting, condensate and where it mounts
- Condensing units extract more heat from the exhaust, run cooler flue temperatures and vent in PVC, which is cheaper to route and travels further. They produce acidic condensate needing a drain and usually a neutraliser cartridge.
- Non-condensing units are cheaper up front and need stainless steel venting, which costs more per foot and limits the run.
- Either way it is a new penetration. Through a wall or roof, with clearances from windows, doors and soffit vents that are not negotiable.
- Where it mounts in Charlotte. Usually the garage wall, an exterior wall or a utility closet. Attic mounting is common in the newer south and southwest subdivisions and needs the condensate route thought through carefully, because that is a ceiling above living space.
Electric tankless: read this before you budget
Whole-house electric tankless is the option that catches Charlotte homeowners out.
- The draw is the problem. A unit capable of running a shower through a January temperature rise pulls around 27 kW, roughly 112 amps at 240 volts, typically across three or four dedicated double-pole breakers.
- Most panels here will not carry it. Not on top of an air conditioner, a range and a dryer, and the service upgrade frequently costs more than the water heater.
- You will hear that at the assessment. Not partway through the install.
- Point-of-use is a different question. For a single remote sink or a garage utility tap, electric is a much more reasonable proposition.
Isolation valves, and why we fit them every time
A tankless service valve kit is a pair of ball valves with hose ports that let a technician isolate the unit and circulate descaling solution through the heat exchanger without cutting anything.
Fitted at installation, it costs a few hundred dollars and makes every future descale a straightforward hour. Left off to shave the quote, every future descale becomes a much bigger job, and in practice it means the unit never gets serviced at all. We fit them as standard and we would encourage you to check that anyone else quoting has included them.
Permits, plainly
A tankless conversion is a permit job, without exception. The NC GS 160D-1110 exemption covers like-for-like connections with no change of fuel, location, capacity, venting or pipe routing. A tankless conversion changes almost all of those.
Expect plumbing and mechanical permits, and electrical too on an electric unit. Mecklenburg contractors pull trade permits online through TIP, which issues instantly and around the clock, so the permit is not what holds the job up. We pull it before we start rather than reconstructing it afterwards. Code Enforcement is on 980-314-2633.
What the job covers in Charlotte
System focus
Gas and electric tankless installation in Charlotte homes: load calculation, gas line sizing, venting, condensate, isolation valves, electrical and permits.
Target outcome
A unit that holds its set temperature at your actual peak flow rate, vented correctly, serviceable, and signed off.
Decision point
A tankless conversion always needs a permit. If a quote does not mention one, that is the question to ask before you sign it.