Pecan Valley Plumbing
Get help with Tankless Water Heaters
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Call (512) 555-0147A tankless unit heats water as it flows instead of storing it, so the work is sizing it to the fixtures it serves, running the gas or electrical supply and venting a new unit needs, and keeping its heat exchanger clear of scale.
01Tankless
Each of these points at something different inside the unit, not the whole system.
A burst of cold in the middle of a shower usually means the flow dropped below the unit's minimum for a moment, or a fixture is drawing less than the unit needs to stay lit. Scale on the heat exchanger can make it worse over time.
Modern tankless heaters display a code for what stopped them: an ignition fault, a blocked vent, low incoming water pressure, a flow sensor issue. The code narrows down what a technician checks first.
Mineral scale narrows the passage inside the heat exchanger, especially with hard water and no softener ahead of it. Flow slows and the unit can no longer keep up with demand it used to meet.
02Gas or electric
Both heat water on demand. What each needs from the building is where they differ.
A gas-fired unit generally delivers more flow and covers a full house's demand more easily. It needs a large enough gas line to feed it and venting rated for the unit, which is often the bigger part of an installation.
An electric unit needs no venting at all, which simplifies where it can go. It draws a heavy electrical load the moment it runs, and the service panel and wiring have to be sized to carry that load without tripping.
Tankless Water Heaters
Serving Round Rock, TX.
03How it works
Two things decide how a tankless unit performs over time: whether it was sized right, and what the water leaves behind.
A tankless heater is rated by how much it can raise the temperature at a given flow rate, not by how many gallons it stores. Cold groundwater in winter demands more from the same unit than warm groundwater in summer, and several fixtures running together demand more than one. A unit sized for a single bathroom can fall behind once a kitchen and a shower draw from it at the same time, which is why sizing looks at the household's peak, not its average.
Minerals in the water settle inside the heat exchanger the same way they would in a kettle, and the narrower the passage gets, the harder the unit has to work to hold its temperature. Periodic descaling clears that buildup and is the main upkeep a tankless heater asks for, more so in areas with hard water than in areas without it.
04What changes the job
None of this applies to swapping one tankless unit for another. All of it applies to a first switch from a tank.
A tankless unit can call for more gas at once than a tank heater ever did, and an existing line sized for the old appliance may need to be upsized to feed it properly.
A gas tankless heater vents differently than a tank, often through a wall or a dedicated vent pipe rather than an existing flue, and routing that vent can be the largest part of a first installation.
An electric tankless unit draws far more current than almost anything else in the panel, and the panel and the wiring feeding it both have to be able to carry that load safely.
A tankless heater mounts on a wall rather than sitting on the floor, so the wall, the clearance around it and the route the gas, power and venting take to reach it all factor into the job.
05Questions
It depends on how many fixtures could run at once and how cold the incoming water is, since a unit has to raise the temperature by more before it can deliver the same flow. Matching the unit to that peak demand is what sizing means.
It depends mostly on how hard the water is. Harder water leaves scale faster, and a unit without a softener ahead of it usually needs the heat exchanger flushed more often to keep its flow and efficiency up.
Gas units generally deliver more flow and suit whole-house demand, but need proper venting and enough gas supply. Electric units skip the venting question but draw a large electrical load, which is not available in every panel.
Water that cannot be stopped, sewage coming up, no water at all, or a smell of gas: urgent. A drip, a slow drain or a running toilet: worth fixing soon, but not tonight. When in doubt, shut off the water to the fixture and ask.
Pecan Valley Plumbing
Call Pecan Valley Plumbing, have us call you, or describe the issue.
Prefer to talk?
Call (512) 555-0147