Tankless Water Heater Installation & Repair in Frisco, TX

A tankless water heater is not a like-for-like swap for a tank, and the two things that make it complicated here are the same two things almost every online cost guide leaves out: the gas supply and the water chemistry. A 40 or 50 gallon tank typically draws around 40,000 BTU. A whole-house tankless unit draws up to 199,000 BTU. That is roughly five times the gas demand through piping that was sized for the smaller appliance, often fifteen or twenty years ago.

The result is a very specific failure mode we are called out to constantly: a correctly specified, well-regarded unit that was installed on an undersized gas branch. It fires, it runs, and then it drops out under load or throws a combustion fault, and the homeowner is told the equipment is faulty. It usually is not. It is being starved.

Gas branch sizing

The diameter and run length of the pipe feeding the appliance, calculated against the total connected load of every gas appliance in the house. A 199,000 BTU tankless unit at any meaningful distance from the meter generally needs 3/4 inch minimum, and sometimes 1 inch.

The second factor is hardness. Frisco municipal water typically tests between 8 and 11 grains per gallon. Every gallon that passes through a tankless heat exchanger deposits a small amount of calcium carbonate on the hottest surfaces in the appliance. Unlike a tank, where scale falls harmlessly to the bottom, in a tankless unit it accumulates directly in the narrow passages where heat transfer happens.

Every tankless unit is advertised with a headline flow rate. Those numbers are real, but they are quoted at a temperature rise far smaller than a Frisco January demands. Flow rate and temperature rise trade directly against each other, and the relationship is arithmetic rather than marketing:

GPM = (BTU x efficiency) / (rise x 500)

500 is the constant for water — 8.34 pounds per gallon, times 60 minutes, times 1 BTU per pound per degree Fahrenheit. Double the temperature rise and you halve the available flow.

Groundwater here arrives at roughly 50 to 55 degrees in January and February. A comfortable shower is about 105 degrees, so the unit must add around 55 degrees. That is near the worst case on any manufacturer's flow chart, and it is the reason a system sized on summer numbers feels excellent for eight months and disappointing exactly when it matters.

This is why we size against the winter rise as standard, and why a large house with two simultaneous showers plus a soaking tub sometimes genuinely needs two units manifolded together rather than one large one. It is a more expensive answer and it is occasionally an unwelcome one, but it is the honest one.

Most whole-house gas tankless installations in Frisco land between $2,500 and $6,500 installed. That is a wide band and the width is the point — the equipment is the predictable part, and the house is the variable. Two identical units in two identical-looking homes can differ by three thousand dollars purely on gas line and vent path.

We quote ranges on this website and firm prices on site, in writing, itemized. Anyone giving you an exact figure over the phone has not measured your gas branch, and that number is going to move once they do.

Tankless units are worth repairing far more often than tanks are, because the expensive component — the heat exchanger — is usually not the thing that failed. Flow sensors, igniters, flame rods, gas valves, control boards and fans are all serviceable parts, and a unit under about twelve years old with a good exchanger is normally worth fixing.

1. 1

   Read the fault code before touching anything

   Modern units self-diagnose reasonably well. The code narrows the cause faster than any amount of guessing, and it is the first thing we ask for on the phone.

2. 2

   Establish whether it has ever been descaled

   In this water, a unit that has never been flushed explains a large share of the intermittent faults we see — flow sensor errors, ignition problems, temperature swings and reduced output.

3. 3

   Check supply before condemning the appliance

   Gas pressure under load, vent obstruction, inlet filter screen blockage. A starved or blocked unit produces symptoms that look exactly like component failure.

4. 4

   Weigh the repair against remaining life

   A heat exchanger replacement on a fifteen-year-old unit rarely makes sense. A control board on a six-year-old unit almost always does.

Frisco did most of its growing in a short window, and the result is that the age of a house here predicts the installation more reliably than its size does. The neighbourhoods either side of the Dallas North Tollway went up at different times to the ones out towards Denton County, and they were plumbed to different expectations.

The attic installations are the ones worth flagging. A tank sitting above a finished ceiling is a flood risk that most homeowners have simply stopped noticing, and it is one of the better non-financial reasons to convert — a tankless unit holds well under a gallon rather than fifty. It also changes the vent conversation, because an attic unit has to get its exhaust out through a roof or gable rather than straight through a wall.

None of this is a reason to prefer one neighbourhood over another. It is a reason to be sceptical of any quote that arrives without someone having looked at your particular house, because the variables that move the price by thousands are all physical and all local.

Electric tankless units are cheaper to buy, simpler to vent — they do not vent at all — and genuinely excellent in the right application. The difficulty in North Texas is arithmetic. Electric resistance heating produces about 3,412 BTU per kilowatt, so matching the output of a 199,000 BTU gas unit means roughly 58 kilowatts, which is not a realistic residential load.

The practical electric ceiling

A large residential electric tankless unit draws around 27 kW, typically across three or four 40-amp double-pole circuits. That is roughly 92,000 BTU of input, which at a 55F winter rise yields about 3 GPM. Enough for one shower. Not enough for two.

On a 200 amp service already carrying air conditioning, an electric range and a dryer, finding 120 amps of spare capacity usually means a service upgrade. That upgrade frequently costs more than the entire gas installation it was meant to avoid, which is why whole-house electric rarely wins here on a house that already has gas.

We install both, and we have no incentive to push you towards either. What we will do is measure the panel before recommending electric, because a unit that trips the service on a January morning is not a saving.

Descaling gets the attention because it is the part that matters most in this water, but a proper annual service is a longer list than a flush. Roughly half the faults we attend in year three onwards would have been caught by someone spending an hour with the unit in year two.

1. 1

   Circulate descaling solution through the exchanger

   Typically 45 to 60 minutes through the isolation valves. This is the part that protects the single most expensive component in the appliance.

2. 2

   Clean the inlet filter screen and the air intake

   Both are cheap, both restrict flow when blocked, and both produce faults that look far more serious than they are.

3. 3

   Inspect the burner, flame rod and igniter

   Oxidation on a flame rod weakens the flame signal until the unit starts failing to prove ignition, usually intermittently before it does so permanently.

4. 4

   Check venting, terminations and condensate

   Joints, screens, clearances, and on condensing units the neutralizer cartridge, which is consumable and does get used up.

5. 5

   Verify gas pressure under load and read the fault history

   The stored error log will often show a developing problem months before it becomes a no-hot-water call.

The cost of skipping it is not really the eventual repair bill. It is the warranty. Manufacturers generally make heat exchanger coverage conditional on documented annual flushing, and hard-water damage is a named exclusion. In water at 8 to 11 grains per gallon, an undescaled unit gives a manufacturer a straightforward reason to decline the most expensive claim you are ever likely to make.

Deliberate. Tankless faults are diagnosed by conversation — what the display shows, what changed, how old the unit is, whether it has ever been flushed, what happens when a second fixture opens. A form throws all of that away and replaces it with a callback queue, which helps nobody at 11pm with a cold house.

Calling (972) 430-9024 reaches someone who can start narrowing the problem down immediately, and quite often finish it without a visit.