Sanders Plumbing Company's Resources
Welcome to the Sanders Plumbing Company podcast, your go-to source for practical plumbing tips, home maintenance advice, and real-world solutions for homeowners and businesses in Knoxville, TN. From leaky faucets and clogged drains to water heaters, sewer lines, remodels, and emergency plumbing issues, Sanders Plumbing Company is here to help you understand what is happening behind the walls and under the floors of your property.
Each episode shares helpful insights, common plumbing warning signs, seasonal maintenance tips, and expert guidance designed to save you time, money, and stress. Whether you are dealing with a small repair or planning a larger plumbing project, Sanders Plumbing Company brings trusted local knowledge and dependable service to the Knoxville community.
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Sanders Plumbing Company's Resources
What Are the Tankless Water Heater Pros and Cons for Knoxville Homes?
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Discover Tankless Water Heater Pros and Cons for Knoxville Homes in this comprehensive guide covering energy savings, installation costs, endless hot water, hard water maintenance, and long-term value. Learn how tankless systems compare to traditional water heaters, what Knoxville homeowners should expect from East Tennessee water conditions, and how professional sizing and installation can maximize efficiency, comfort, and performance for your home.
You know that moment of absolute dread, right? Like you're in the middle of a morning shower, shampoo in your hair, completely relaxed, the bathroom is all seamy, and then boom, the water temperature just drops by twenty degrees.
SPEAKER_00Oh man. Yeah. It is a universal and miserable human experience. And for generations, we've basically just accepted it as this, you know, unchangeable law of household physics. When the hot water is gone, it's just gone. And you're stuck shivering, waiting an hour for the system to recover.
SPEAKER_01Right, exactly. But recently, there's this incredibly seductive homeowner fantasy floating around. It's the promise that you could just install this magical compact box on your utility room wall and literally never run out of hot water again.
SPEAKER_00Yeah, the marketing pitch is always about endless, continuous heat.
SPEAKER_01Endless heat. And that is exactly what we are pulling apart today. We are taking a magnifying glass to the real-world pros, cons, and the frankly surprising hidden realities of tankless water heaters. Our source material for this deep dive is a highly specific boots on the ground manual titled The Knoxville Tankless Water Heater Guide, Performance and Planning.
SPEAKER_00And, you know, while that guide is highly localized to Tennessee, the mechanics and the infrastructure hurdles it details, they apply universally.
SPEAKER_01Oh, for sure. Right.
SPEAKER_00So whether you are living in Knoxville or Seattle or anywhere in between, understanding this technology is crucial. Making the switch is not just about avoiding a cold shower for you. We are talking about a massive financial, structural, and chemical decision for your home.
SPEAKER_01Yeah, it fundamentally changes how your house manages one of its most expensive and vital resources. But before we can even try to figure out if a tankless system is worth the thousands of dollars it usually costs to install, we have to understand the mechanics. We need to look at how it physically changes the way a house generates hot water.
SPEAKER_00Exactly. And to do that, we need to compare it to that giant metal cylinder most of us have sitting in a dark corner of our basements. Let's establish that traditional baseline first.
SPEAKER_01Okay, yeah. Lay it out for us.
SPEAKER_00So the standard conventional water heater is basically a six-foot-tall insulated steel reservoir. It holds around 50 gallons of water. And its entire operational purpose is to heat that water to about 120 degrees and just keep it there 24 hours a day, seven days a week.
SPEAKER_01Right. Even when you are asleep at two in the morning or at work all day or literally away on a two-week vacation.
SPEAKER_00Exactly. Which introduces a massive hidden cost that the industry calls standby energy loss. Because, you know, no tank is perfectly insulated, right? Heat constantly escapes.
SPEAKER_01Making it incredibly inefficient.
SPEAKER_00Right. Your heater's thermostat registers that temperature drop, clicks on the gas burner or the electric element, and burns energy just to reheat water you aren't even actively using. Plus, that big metal tank is under constant physical stress.
SPEAKER_01Because of the water pressure.
SPEAKER_00Yeah, it's constantly heating, expanding, cooling, and dealing with 60 to 80 pounds of static water pressure. That constant thermal expansion and contraction just weakens the steel in the internal glass lining. So because of that physical toll, a traditional tank usually only survives about 10 to 15 years before it inevitably corrodes and needs to be completely replaced.
SPEAKER_01Okay, let's unpack this. If that is the antiquated way we've been doing things, we need to look at how the tankless alternative actually functions. To me, having a traditional tank is essentially like keeping your car idling in your driveway 24 hours a day, burning gas, just in case you suddenly need to run to the grocery store.
SPEAKER_00Oh, that is a great way to think about it.
SPEAKER_01Yeah, and so tankless technology is simply the act of turning the car engine on only when you are sitting in the driver's seat and actually ready to put it in gear.
SPEAKER_00That analogy perfectly captures the demand type heating mechanism. Instead of a massive 60-inch tall tank taking up all this floor space, you have a compact, wall-mounted unit roughly the size of a carry-on suitcase.
SPEAKER_01Which is crazy to think about. Just a suitcase.
SPEAKER_00Right. And when you turn on your shower, cold water flows from the street pipe directly into this unit. It immediately hits a heat exchanger, which is typically constructed of copper, and shaped into this dense labyrinth of parallel plates or fin tubes.
SPEAKER_01So the goal is to create as much surface area as possible in a very tight space.
SPEAKER_00Exactly. The moment the water starts flowing into that copper maze, a high-powered gas burner or a massive electric element fires up and flash heats the water as it rapidly passes through.
SPEAKER_01And the actual internal mechanics of how it accomplishes that flash heating seamlessly is where the engineering gets fascinating to me. It doesn't just blast a single uniform flame, right?
SPEAKER_00No, not at all. The guide talks about how the system relies on an internal negative feedback loop. There is a small turbine flow sensor at the inlet that physically spins when you open a tap.
SPEAKER_01Okay, so that sensor tells the computer board exactly how fast the water is moving.
SPEAKER_00Yes. And it is paired with components called thermistors, which are these highly sensitive temperature sensors. There is a thermistor at the cold water inlet, reading the exact temperature of the groundwater coming from the street, and another thermostat at the hot water outlet.
SPEAKER_01So the computer board is constantly doing real-time math. It looks at the incoming temperature, looks at how fast the water is moving, and calculates exactly how much fuel it needs to burn to hit your target shower temperature.
SPEAKER_00Precisely. If someone else in the house turns on a sink and the flow speeds up, the computer instantly tells the modulating gas valve to open wider and fire the burner hotter.
SPEAKER_01And if they turn the sink off, it throttles the flame down. It is making micro adjustments multiple times a second to ensure the water hitting your skin stays at the exact temperature you set, which is honestly incredible.
SPEAKER_00It really is. And because the unit shuts off entirely the second you turn off the tap, it completely eliminates that standby energy drain. It operates at zero fuel consumption when idle.
SPEAKER_01So knowing that the system only runs when a tap is on, the natural next question is what does that on-demand approach actually do for your daily life and, you know, your utility bills?
SPEAKER_00Well, the comfort factor is definitely the primary selling point. It is the promise of an endless flow. Because there is no 50-gallon reservoir to drain dry, there's zero recovery time.
SPEAKER_01Right. So you can take back-to-back showers for three hours straight, run the dishwasher, and run multiple loads of hot laundry one right after the other, and you will never experience that dreaded cold water interruption we talked about earlier.
SPEAKER_00Exactly. Beyond the luxury of endless showers, there is a significant physical and psychological payoff, too. You are reclaiming valuable basement, garage, or utility closet square footage.
SPEAKER_01Oh, yeah. That alone is a huge win for a lot of people.
SPEAKER_00But reading through the structural assessments and the source material, the safety aspect is really paramount. You are completely eliminating the risk of a 50-gallon tank rusting out, rupturing, and dumping a massive volume of water onto your floors.
SPEAKER_01Which is a nightmare. I mean, while small connection leaks are still a possibility with any plumbing fixture, the catastrophic drywall and flooring damage from a tank failure is essentially removed from the equation. No more massive mold issues.
SPEAKER_00Right. And the mathematical payoff in energy efficiency is just as compelling. Although the breakdown of those savings reveals some surprising counterintuitive math.
SPEAKER_01Here's where it gets really interesting. Overall, tankless heaters use 30 to 50% less energy than conventional tanks. But when you look at the usage breakdown, a home with low hot water usage, meaning they use 41 gallons or less per day, sees a massive efficiency spike of 24 to 34% over a standard tank.
SPEAKER_00But for a high usage home like a large family that uses around 86 gallons a day, the relative efficiency drops to only 8 to 14% better than a standard tank.
SPEAKER_01Which sounds entirely backward on the surface. You would naturally assume the more you use the efficient machine, the more money you save.
SPEAKER_00Yeah, you would think so. But going back to your idling car analogy, the math makes perfect sense. The standby heat loss of a traditional tank is a fixed penalty. It loses a set amount of heat into the basement air every single day, no matter what.
SPEAKER_01So if you don't use much hot water, that fixed penalty makes up a huge, disproportionate percentage of your total energy bill. Eliminating that penalty saves you a massive chunk of your bill.
SPEAKER_00Exactly. But if you are a high usage family running the hot water constantly, the energy spent actively heating the water dwarfs the standby loss. The time you spend idling is a much smaller percentage of your overall fuel use.
SPEAKER_01That makes total sense. But regardless of whether you are high or low usage, those long-term savings do accumulate. The guide notes that Tennessee homeowners save roughly $100 annually on utility bills.
SPEAKER_00Yes, because these units don't suffer the thermal expansion stress of a storage tank, their lifespan is routinely 20 years or more. Over that extended lifespan, you are looking at roughly $2,000 in utility savings.
SPEAKER_01Okay, so if the technology lasts twice as long as a conventional tank, reclaims floor space, prevents catastrophic basement floods, and lowers utility bills by thousands of dollars over its lifespan, why doesn't every single house in the country have one installed by default?
SPEAKER_00That brings us to the reality check. The answer is localized infrastructure. Retrofitting an older house to handle the intense demands of flash heating water is a massive logistical hurdle.
SPEAKER_01Yeah, the sticker shock detailed in the guide is pretty sobering. The average installation comes in at $2,637.
SPEAKER_00And a range is incredibly wide too.
SPEAKER_01Right. A straightforward install might be $1,400, but if you need infrastructure upgrades, it easily hits $4,000 and can skyrocket to a staggering $8,000 at the high end. The specialized labor alone runs anywhere from $600 to $1,850.
SPEAKER_00It is a profound upfront investment. And part of that cost involves sizing the unit correctly, usually because of a fundamental misunderstanding of what these machines can actually do.
SPEAKER_01Because the marketing always promises endless hot water. But you constantly hear horror stories from homeowners who installed a tankless system and complained that the shower goes completely cold the moment someone flushes a toilet or runs the washing machine.
SPEAKER_00Yeah, that happens a lot.
SPEAKER_01Wait, so endless just refers to time, not volume. I can run the shower for 24 hours straight, but if I try to run the shower, the kitchen sink, and the washing machine in the exact same second, the unit physically can't keep up with the sheer volume of water rushing through those copper pipes.
SPEAKER_00That is the crucial distinction between endless supply and limited capacity. Capacity is measured by flow rate, specifically gallons per minute or GPM.
SPEAKER_01Okay, GPM. Got it.
SPEAKER_00Right. So a tankless system can heat water endlessly, but it can only transfer heat to a certain maximum amount of water at any given exact second. Electric tankless systems, for example, typically top out at a flow rate of about eight gallons per minute.
SPEAKER_01Let's visualize what eight gallons a minute actually looks like during a morning rush hour in a typical house. A standard modern shower head uses about two and a half gallons a minute.
SPEAKER_00And a bathroom sink might pull one and a half gallons. A modern washing machine pulls maybe three gallons a minute on a hot fill.
SPEAKER_01Okay, so a household of two people generally requires about six to eight gallons per minute to operate comfortably without overlapping demands. But a busy family of four easily requires an eight to ten GPM capacity.
SPEAKER_00Exactly. So if two showers are running simultaneously and the washing machine kicks on, your house is suddenly demanding 10 gallons of hot water every minute. But your unit can only physically flash heat eight.
SPEAKER_01And then what happens internally? The thermistors read that the water rushing out is dropping below the target temperature, but the gas valve is already open 100%.
SPEAKER_00Yep, the burner is totally maxed out.
SPEAKER_01The water is simply flowing through the copper labyrinth too quickly to absorb the heat. The result is a sudden, frustrating temperature drop at the shower head. You haven't run out of water, but you have exceeded the heat transfer capacity.
SPEAKER_00Which means upgrading to a unit with a higher GPM capacity to solve that problem brings us right back to those massive installation costs. High capacity units require high capacity infrastructure. Let's look at the fuel requirements, starting with the gas units.
SPEAKER_01Okay, so a gas tankless heater itself costs between $1,000 and $1,500. But you absolutely cannot just swap it into the old tank spot and use the existing exhaust pipe, right?
SPEAKER_00No, definitely not. The guide details how these units fire incredibly hot and fast, transferring almost all of their heat to the water. That sounds incredibly efficient. But the byproduct is that the exhaust gas leaving the unit is actually relatively cool compared to a standard tank.
SPEAKER_01Right, cool exhaust. That sounds like a good thing.
SPEAKER_00You'd think so, but because the exhaust is cooler, the moisture inside the exhaust gas condenses into a liquid before it can exit the chimney. And that condensation is highly acidic.
SPEAKER_01Oh wow. So if you vent a tankless heater into standard galvanized ducting, the acidic condensation will just eat right through the metal.
SPEAKER_00Exactly. It requires specialized category three, stainless steel, or high-grade PVC venting, installed with slightly pitched angles to drain the condensation safely. Upgrading the venting alone can add $1,000 to the project.
SPEAKER_01And you might also need a plumber to install wider gas supply lines to handle the sudden massive draw of fuel when the burner kicks into high gear.
SPEAKER_00Right. And honestly, the infrastructure barriers for electric units are arguably even steeper, especially in older homes. The hardware for an electric unit is slightly cheaper, around $800 to $1,500.
SPEAKER_01But they demand an astronomical amount of instant electrical current to flash heat water without a gas flame. I mean, most whole house electric tankless heaters require a dedicated 200-amp electrical service.
SPEAKER_00Yes. And many homes built before the late 1990s only have a 150 amp or even a 100 amp electrical panel for the entire house.
SPEAKER_01That's a huge problem.
SPEAKER_00It is. Furthermore, electrical codes dictate that a panel shouldn't operate continuously beyond 80% of its total rated capacity to prevent overheating and fire risks.
SPEAKER_01So if you try to wire a high-capacity electric tankless heater into an older 150-amp panel, the moment it kicks on alongside your HVAC system and your electric oven, you will instantly trip the main breaker and shut down the entire house.
SPEAKER_00Yep. You have to hire an electrician to upgrade the entire electrical panel. That means pulling permits, getting a new, heavier service wire dropped from the street by the utility company, and installing a larger breaker box.
SPEAKER_01And that electrical overhaul is exactly where those eye-watering $8,000 total project costs come from.
SPEAKER_00Exactly. Now let's assume you have the budget. You upgrade the gas lines, you install the stainless steel venting, you upgrade the electrical panel, and you size the GPM capacity perfectly for your family of four. The physical installation is flawless.
SPEAKER_01Everything is perfect.
SPEAKER_00Right. The Knoxville Guide points out a hidden local environmental enemy that will immediately begin quietly destroying that expensive machine from the inside out. Your municipal water quality.
SPEAKER_01Ah, the silent killer of complex plumbing appliances. The guide zeroes in on the Knoxville area's geology, but it prominently notes that 85% of the United States geography suffers from hard water. So this localized threat applies to almost everyone listening.
SPEAKER_00Absolutely. Hard water contains high concentrations of dissolved minerals, primarily calcium and magnesium. Earlier, we discussed the copper heat exchanger, that dense labyrinth of parallel plates and tubes responsible for flash heating the water.
SPEAKER_01Right, the maze.
SPEAKER_00Yes. When hard water is rapidly heated to 120 degrees inside those tight tubes, the calcium and magnesium physically precipitate out of the water and bake directly onto the internal walls of the copper and creates a hardened scale buildup.
SPEAKER_01It is like trying to quickly boil a pot of water on the stove, but the inside of the metal pot is coated with an inch thick layer of solid rock chalk. The heat from the burner hits the bottom of the pot, but it can't efficiently penetrate that chalk barrier to actually reach the water inside.
SPEAKER_00That is a perfect visualization. The chalk scale acts as a powerful thermal insulator. And the consequences of that insulation inside a tankless system are catastrophic.
SPEAKER_01Because the outlet thermostur senses that the water isn't getting hot enough, right, since the heat is being blocked by the scale.
SPEAKER_00Exactly. The computer board reacts by telling the gas valve to open wider. The burner blasts maximum intense heat against the outside of the copper tubes, trying desperately to punch through the scale layer.
SPEAKER_01But the water isn't absorbing the heat, which means the copper metal itself absorbs all of it. The heat exchanger severely overheats. The copper can physically warp, crack, or burn out entirely, basically destroying the machine.
SPEAKER_00Which elevates the problem from frustrating temperature fluctuations to total hardware failure. The guide is explicitly clear about the warranty dangers associated with this. Water hardness is measured in grains per gallon or GPG.
SPEAKER_01Okay. Grains per gallon.
SPEAKER_00Right. Water treatment, like a whole house softener, is highly recommended by manufacturers if your water hardness exceeds seven grains per gallon. But if it surpasses 12 grains per gallon, major manufacturers like Noritz and Renee will explicitly void your warranty.
SPEAKER_01Wow. They just won't cover it.
SPEAKER_00No, they will not cover a cracked heat exchanger if the failure was caused by local mineral deposits.
SPEAKER_01So to keep the warranty valid and prevent the machine from destroying itself, the maintenance schedule has to be rigorous. I mean, a traditional tank might get hooked up to a hose and flushed out once a year if the homeowner even remembers. But in hardwater areas like Knoxville, a tankless unit requires a dedicated chemical descaling process every six to nine months.
SPEAKER_00And this isn't a simple flush. Plumbers install special isolation valves during the initial setup. To descale the unit, you have to shut off the main water supply, hook up a submersible pump, drop it into a five-gallon bucket of food-grade white vinegar or specialized descaling acid, and physically pump that acidic solution through the heat exchanger in a continuous loop. For how long? Usually for 45 minutes to an hour. The acid slowly dissolves the calcium baked onto the copper. If you neglect that chore, you are basically guaranteeing a premature system failure.
SPEAKER_01Man, as if the dissolved minerals weren't enough of a geographic threat, the guide also brings up the climate factor, specifically the incoming winter groundwater temperature.
SPEAKER_00Right. The temperature of the water traveling to the pipes buried under the street fluctuates wildly depending on the season. In the middle of July, the incoming water might be a relatively warm 70 degrees.
SPEAKER_01So the tankless heater only has to raise the temperature 50 degrees to hit a comfortable 120-degree shower.
SPEAKER_00Exactly. But in the dead of winter in Tennessee, or further north, that groundwater can easily drop to 40 degrees. Suddenly the machine has to achieve an 80-degree temperature rise.
SPEAKER_01That massive required temperature jump must drastically lower the effective flow mate capacity of the unit, right? The water has to move much slower through the copper labyrinth to absorb enough heat.
SPEAKER_00Yes, exactly. A unit that effortlessly provides eight gallons a minute during a summer heat wave might functionally throttle down to only five gallons a minute in January.
SPEAKER_01Which completely exacerbates all those peak demand bottlenecks we discussed earlier. Your shower suddenly goes cold just because it's snowing outside.
SPEAKER_00Aaron Powell It is wild to think about, but yes.
SPEAKER_01We have looked at a staggering number of moving parts today. We've got gallons per minute, grains per gallon, electrical panel amp loads, acidic condensation venting, and winter ground temperatures. So what does this all mean? How does a homeowner actually synthesize all of this and make a decision without making an $8,000 mistake?
SPEAKER_00Aaron Powell Well, it ultimately comes down to calculating long-term operating costs against those steep upfront costs, and acknowledging that this is really not a do-it-yourself project. Looking at the operating divide, gas units require expensive specialized venting and potentially larger gas lines to install. However, natural gas is generally cheaper than electricity, so they only cost between $195 to $245 a year to actually run.
SPEAKER_01Conversely, electric units are generally cheaper to buy, assuming your home's electrical panel can already handle the massive amp draw, but they cost significantly more to operate month to month. The guide estimates an annual operating cost of $535 to $580.
SPEAKER_00Which really highlights why the guide aggressively emphasizes the necessity of hiring a local professional. Buying a tankless heater isn't like buying a new refrigerator where you just plug it into the wall.
SPEAKER_01No, it is a highly complex, interconnected math equation dictated entirely by the physical and chemical characteristics of your specific property. You cannot just rely on generic online calculators.
SPEAKER_00Exactly. A qualified local plumber isn't just soldering pipes together. They are conducting a comprehensive environmental assessment of your home. They physically test your municipal water to determine the exact grains per gallon to ensure you don't void a $2,000 warranty on day one.
SPEAKER_01And they measure your incoming static water pressure. They calculate your exact electrical panel load to ensure you don't violate that 80% continuous safety rule.
SPEAKER_00And most importantly, they know exactly how the local winter ground temperatures will impact the specific brand and model's flow rate, ensuring your family actually gets the capacity they need in February.
SPEAKER_01It is a stark reminder that the environment outside your house completely dictates the viability of the technology you can use inside your house.
SPEAKER_00Totally. Synthesizing all the data from the Knoxville Guide, the modern tankless water heater is a genuine marvel of residential engineering. It offers a lifespan that doubles conventional technology, it reclaims valuable square footage in the home, and it definitively eliminates the wasteful standby energy loss that plagues storage tanks.
SPEAKER_01But it demands immense respect. It demands a rigorous localized compatibility check with your home's electrical grid, your gas infrastructure, and your local water chemistry. To avoid turning a dream home upgrade into a logistical and financial disaster.
SPEAKER_00It is a profound investment in long-term efficiency, but that investment only yields a return if the foundation of the house can physically support it.
SPEAKER_01The next time you turn on your shower and you feel that perfectly warm water hit your shoulders, you are probably going to be thinking about the hidden mechanics. You'll be picturing the spinning flow sensors, the dense copper plates, the thermistors constantly calculating the temperature and the energy costs flowing through the walls right behind the tile. It fundamentally changes how you view a simple morning routine.
SPEAKER_00It really peels back the curtain on the complex infrastructure required to maintain modern comfort.
SPEAKER_01It really does. And before we wrap up, I want to leave you with one final thought to mull over, something that pushes beyond the current technology we've analyzed today. With all these massive infrastructure hurdles, you know, the heavy electrical panel upgrades, the acidic gas venting, the flow rate limits, what if the future of home design completely abandons the concept of centralized water heating altogether? Oh wow. Yeah. Imagine a future where there are no hot water pipes running through your walls from a utility room. Instead of a giant tank in the basement or even a centralized tankless box on the wall, imagine if there was a micro tankless heat exchanger built directly into the nozzle of every individual's sink and shower head in the house. Right. The water travels through the house cold and is only flash heated in the final fraction of a second before it touches your hands. Now that would be the ultimate realization of on demand efficiency. Until next time, stay curious.