Tankless water heater installation

It will not run out from a duration standpoint. You can shower for an hour. But it has a hard flow limit: beyond its gallons-per-minute capacity at the current temperature rise, the outlet temperature drops. So it never runs out, but it can be overwhelmed by too many fixtures at once. That is why correct sizing at a winter temperature rise matters so much.

No. The delay at a fixture is the time it takes to push the cooled water already sitting in the pipe out of the way, and that is identical whether the heat source is a tank or a tankless unit. Some units add a second or two of ignition delay. If a slow tap is the complaint, the answer is a recirculation line or a point-of-use unit, not tankless in general.

Typically $4,000 to $6,500 for a conversion that includes upsizing the gas line and running a new sealed sidewall vent. A rare straight swap where gas and venting already suit can be $3,000 to $4,500; a difficult vent route or a long gas run pushes toward $8,500; two cascaded units for a high-demand house run $8,000 to $14,000. The unit itself is a minority of that. The gas and vent work is the bulk.

Because volume, not just presence, is what matters. A conventional 40-gallon tank draws around 40,000 BTU and lives happily on a half-inch branch. A whole-house tankless draws 150,000 to 199,000 BTU. Delivering that at proper pressure, alongside a furnace and a range, usually needs three-quarter-inch or one-inch pipe and occasionally a larger meter. Any quote that has not addressed this is incomplete.

Usually yes, and you gain the floor space, but the vent has to go somewhere. Condensing units vent through a sidewall in sealed plastic pipe, so the practical question is whether there is a suitable exterior wall within reach with correct clearances from windows, doors, soffits and the gas meter. An old chimney or B-vent flue cannot be reused.

Annually in hard water, every two years in soft water. Much of Virginia is moderately hard, and well water in the Valley and Piedmont can be very hard. Descaling is a circulating acid flush through the isolation valves and takes under an hour. Skipping it is the main reason tankless units fail early, and manufacturers often require documented maintenance to honour the heat exchanger warranty.

Yes, but their capacity drops as the incoming water gets colder, because the unit has to achieve a bigger temperature rise. A unit rated 9.8 gpm at a 35-degree rise delivers around 5 gpm at the 75-degree rise a Virginia February demands. Units on exterior walls or in unconditioned garages also rely on powered freeze protection, which makes a winter power cut a genuine risk.

You get no hot water. Gas tankless units need electricity for the fan, ignition and controls. A conventional standing-pilot gas tank keeps whatever is already hot in the tank and can even continue heating. If outages are common where you live and hot water during them matters, that is a real point against tankless, or an argument for a small generator circuit.

For a whole house, rarely. Whole-house electric tankless units draw enormous current, often 100 to 150 amps, which typically means a service upgrade costing more than the heater. They make good sense as point-of-use units for a single remote sink or a workshop. For an all-electric house wanting efficiency, a heat-pump tank is the far better answer.

Twenty to twenty-five years is the normal expectation with annual descaling, against eight to twelve for a storage tank. Heat exchangers are commonly warranted twelve to fifteen years. That longevity is the strongest part of the financial case: you buy one tankless unit where you would have bought two tanks, and it is a much smaller thing to fail when it eventually does.