Honestly, $3,900 is a solid deal for a tank to tankless swap. Most plumbers on r/askaplumber would call that fair or even a little cheap. The national average for a gas tankless conversion runs about $3,500 to $5,600 according to HomeAdvisor and HomeGuide.

The real question is what is included in that number. Does the $3,900 cover the gas line upgrade? New venting? Removal of the old tank? Permits? If those are all baked in, you found a good contractor. If those are extra line items waiting to surprise you, the final bill could hit $5,000 or more.

Always ask for a written breakdown. A good quote shows the unit cost, labor, venting, gas line work, removal, and permits as separate items. That way you know exactly where your money goes. No surprises is the goal.

Let’s keep it real. The Department of Energy says a tankless unit can save you about 24 to 34 percent on water heating costs compared to a traditional tank. For most homes, that works out to roughly $75 to $120 per year on gas or about $50 to $95 on electric.

ENERGY STAR puts the number around $95 per year for a typical household. So we are talking about $8 to $10 a month in savings. Not bad, but nobody is getting rich off it.

The savings really stack up over 15 to 20 years since tankless units tend to last twice as long as tank models. Where it matters most is in homes that use a lot of hot water. A family of five running showers, laundry, and the dishwasher will notice the difference more than a retired couple who barely uses hot water. Your mileage will vary based on your actual usage.

A regular tank swap is basically plug and play. Same spot, same connections, done in two hours. A tank to tankless conversion is a different animal. You are changing the whole setup.

Most gas tankless units need 150,000 to 199,000 BTUs. Your old tank probably used 30,000 to 50,000. That means the gas line feeding it is too small and needs to be upgraded. That alone can run $300 to $2,000 depending on how far the line has to go.

Then there is venting. Your old tank vent cannot be reused. A new stainless steel or PVC vent run has to be installed, which means cutting holes in walls. That adds $200 to $800. You also need new water connections, possibly electrical work for the ignition system, permits, and someone has to haul that old tank away.

Add it all up and you can see why a $1,200 tank swap becomes a $4,000 to $6,000 tankless conversion. It is more work, plain and simple.

This depends on the math for your specific situation. If the conversion costs $4,500 more than a tank swap and you save $100 per year on energy, simple math says 45 years to break even. That is not great.

But that is not the full picture. Tank water heaters last 8 to 12 years. Tankless units last 15 to 20 years. So over 20 years, you might buy two tanks but only one tankless. Factor in the cost of that second tank replacement and the payback looks more like 12 to 18 years.

If you can grab a federal tax credit (up to $600 for qualifying ENERGY STAR models) or a utility rebate, the payback gets shorter. In areas with high gas or electric rates, it gets even better.

Bottom line: tankless does not pay for itself fast. You buy it for endless hot water, longer life, and a smaller footprint. The savings are a bonus, not the main reason.

Most plumbing contractors mark up materials somewhere between 25 and 50 percent. On a tankless job, that includes the unit itself, venting materials, fittings, gas line parts, and anything else going into the wall.

Then there is labor markup on top of your hourly cost. After you add overhead like insurance, truck, fuel, licensing, and callbacks, a healthy total markup on the job usually lands between 40 and 65 percent over your hard costs. Homewyse notes that their estimates actually exclude overhead and markup, which is why real quotes come in 30 to 50 percent higher than their numbers.

If you are pricing tankless conversion jobs and your margins feel thin, you might be undercharging for the infrastructure work. Gas line upgrades and venting are skilled labor. Price them accordingly. A tool like QuoteIQ can help you build accurate line item quotes so nothing falls through the cracks.

A tank swap is your bread and butter. You know the scope, you know the time, and you can quote it confidently in 30 seconds. Most tank swaps run $1,200 to $2,500 installed and take 2 to 4 hours.

A tankless retrofit is a totally different conversation. You need to scope the gas line situation, check the venting path, look at electrical access, and figure out where the unit is going. All of that takes time and all of it costs money.

My advice: quote tank swaps and tankless retrofits as completely different jobs. Build your tankless quotes with line items for the unit, labor, gas line work, venting, removal, permits, and any electrical. Do not bundle it into one lump number because customers will compare your $4,500 tankless quote to someone else’s $1,800 tank quote and think you are ripping them off.

Show the breakdown so they understand what they are paying for. A good quoting tool like QuoteIQ or Handoff makes this easy to present professionally.

Yes, and this is the part most people miss. The federal 25C tax credit lets you claim 30 percent of the cost of a qualifying ENERGY STAR gas tankless water heater, up to $600 per year. That is real money off your tax bill, not just a deduction.

On top of that, many states and utility companies offer their own rebates. Some are surprisingly generous. SoCalGas for example has offered $800 to $1,200 in rebates for high efficiency water heaters. Your local gas or electric company may have similar programs.

To qualify for the federal credit, you need a unit that meets ENERGY STAR standards. Most name brand condensing gas tankless models qualify. Keep your receipt and the manufacturer spec sheet because you will need them at tax time.

One catch: electric tankless units generally do not qualify for the federal credit. The tax credit is aimed at gas and propane models with a high Uniform Energy Factor rating. Check energystar.gov for the current list of qualifying models.

Technically, you can install anything yourself. The question is whether you should. And with a tankless water heater, the answer is almost always no.

A gas tankless install involves running a bigger gas line, installing new venting through an exterior wall, connecting water lines, and making sure everything meets code. One mistake on a gas line and you have a leak. One mistake on the vent and you have carbon monoxide in your house. Neither of those is a weekend warrior situation.

Electric tankless is a bit more DIY friendly, especially point of use units for a single sink. But a whole house electric tankless still needs dedicated 240 volt circuits that require an electrician. Most jurisdictions also require a permit and inspection for water heater installations.

Here is the other thing. If you install it yourself and something goes wrong, the manufacturer warranty might not cover it. Most brands require professional installation to honor their warranty. So you could save $1,000 on labor and lose $2,000 on a warranty claim. Not worth it in most cases.

Electric tankless installs are the quick ones. A straightforward electric whole house replacement takes about 3 to 5 hours. A point of use unit at a single sink might take an hour or two. Homewyse estimates about 5.6 hours for a typical electric job including setup and cleanup.

Gas tankless is a different story. Homewyse puts the average at about 13 labor hours. That sounds like a lot until you realize what is involved. You are running new venting, possibly upgrading the gas line, mounting the unit, connecting all the plumbing, testing, and cleaning up.

A simple gas tankless replacement where the venting and gas line are already right takes about 4 to 6 hours. A full tank to gas tankless conversion with gas line upgrades and new venting can easily take a full day or stretch into two days on older homes.

For contractors bidding these jobs, always add a buffer for surprises. Old homes especially love to hide problems behind walls.

This is where the real cost lives and where most people get sticker shock. Here is the common hit list.

Gas line upgrade: Your old tank used maybe 40,000 BTUs. A tankless unit needs 150,000 to 199,000 BTUs. That tiny half inch gas line is not going to cut it. Upgrading to three quarter inch or larger runs $300 to $2,000 depending on the distance back to the meter.

Venting: You cannot reuse the old B vent from your tank. Gas tankless units need their own dedicated vent, either stainless steel or PVC depending on the type. Budget $200 to $800 for new venting.

Electrical: Even gas units need a 120 volt outlet for the control board. If one is not nearby, an electrician needs to add one. Going electric tankless? You might need 2 to 3 dedicated 240 volt circuits and possibly a panel upgrade ($250 to $1,500).

Other items that pop up include a condensate drain for condensing units ($100 to $300), water line modifications, and permits ($50 to $300). Plan for at least one surprise.

Oh boy. Older homes are an adventure. Here is what we typically run into on houses from the 1950s and 1960s.

The gas line is almost certainly undersized. Homes from that era were piped for much smaller gas loads. You might need to run a whole new gas line from the meter. That can be the single biggest cost on the job, sometimes $1,000 to $2,000 by itself.

The existing plumbing is probably galvanized steel, which is corroded inside and restricts flow. You may need to re pipe at least the section near the water heater. Half inch supply lines are common in older homes and some tankless units want three quarter inch connections.

Electrical is another wildcard. Many 1960s homes have 100 amp service or less. If you are going electric tankless, a panel upgrade is almost guaranteed.

Then there is the fun stuff like asbestos on old pipes, lead solder, weird framing, and walls that have never been opened. Budget extra for the unknowns. A complex retrofit on an older home can easily hit $5,000 to $10,000 total.

Each location has trade offs. There is no single best answer, but there are some clear winners depending on your house.

Inside a utility room or closet is the most common choice. The unit stays protected from weather, and you get easy access for maintenance. The downside is you need proper venting through an exterior wall and clearance from combustibles. You also need to deal with condensate drainage if it is a condensing unit.

Garage mounting works great in warm climates. You have space, easy wall access for venting, and you do not take up living space. In cold climates, an unheated garage can freeze the unit, so you will need freeze protection or a heated enclosure.

Outside mounting saves you the venting headache entirely since the exhaust just goes straight into the air. Many brands make outdoor rated models. The downside is weather exposure, possible freezing issues in northern states, and you need a weatherproof electrical connection. Southern states like Florida and Texas do outside installs all the time and it works great.

Wherever you mount it, keep it close to the fixtures that use the most hot water. Long pipe runs waste energy and increase wait time.

After years of seeing botched installs and reading inspector horror stories on the NACHI forum, here are the big ones.

Undersized gas line is number one. Some contractors just hook into the existing half inch line and call it done. The unit fires up fine with one faucet. Open two showers and it chokes. Always verify the gas line can deliver enough BTUs to the unit at full demand.

Wrong venting material is number two. Non condensing units need stainless steel Category III vent. Using PVC on a non condensing unit is a code violation and a safety hazard. Condensing units use PVC because their exhaust is cooler. Mix them up and you have a problem.

Skipping the condensate drain on condensing units is another one. That acidic condensate has to go somewhere. Dumping it into a bare copper drain line will eat through the pipe.

Other common mistakes include not installing isolation valves for flushing, ignoring clearance requirements near windows and doors, and forgetting the sediment trap on the gas line. Read the installation manual. Every single page.

Gas tankless pros: Higher flow rates, works in cold climates, can handle multiple fixtures at once. A good gas unit pushes 8 to 10 GPM, enough for two showers and a dishwasher. Gas also heats water faster because it creates more BTUs per minute.

Gas tankless cons: More expensive to install ($2,500 to $5,600 total), needs venting, may need a gas line upgrade, requires annual maintenance, and the install takes a full day or more.

Electric tankless pros: Cheaper to buy ($450 to $1,500 for the unit), simpler installation, no venting needed, smaller footprint, and nearly zero maintenance. Great for mild climates or single fixture setups.

Electric tankless cons: Limited flow rate in cold areas, often needs a 200 amp panel or dedicated high amp circuits, whole house electric units struggle when groundwater is below 50 degrees, and your electric bill might go up more than you expect.

The short version: gas wins for whole house hot water in most situations. Electric wins for point of use and mild climates where you do not need huge flow rates.

Because most of them have been burned by callbacks. And they are not wrong to be cautious.

A whole house electric tankless heater can draw 100 to 150 amps. That is massive. Many homes only have 150 or 200 amp total service for the entire house. Dedicating that much power to a water heater does not leave much for everything else.

The electrical work alone can cost $500 to $1,500 for new circuits and possibly a panel upgrade. That is before the plumber even touches a water line. And if the unit cannot keep up in winter because the incoming water is 40 degrees, guess who gets the angry phone call? The plumber.

In northern states with cold groundwater, electric tankless whole house units are basically a non starter unless you are willing to install multiple units. The temperature rise math just does not work at high flow rates when the water comes in that cold.

Most plumbers would rather recommend a gas tankless or a heat pump water heater and avoid the headache entirely. For point of use at a single sink or bathroom, electric is fine. For the whole house up north, stick with gas.

For whole house use? It is a tough sell. Here is why the numbers work against you.

To get hot water at 120 degrees from 40 degree groundwater, the unit needs to raise the temperature by 80 degrees. Most whole house electric tankless units max out around 3 to 4 GPM at that temperature rise. A single shower uses about 2.5 GPM. So you can run one shower and maybe a sink, but two showers at the same time? Not happening.

In Florida where groundwater comes in at 70 degrees, that same electric unit can push 6 to 8 GPM because it only needs to raise the temperature 50 degrees. Huge difference.

If you live in Minnesota, Wisconsin, New York, or anywhere with cold groundwater, a whole house electric tankless is going to disappoint you. Gas tankless or a heat pump water heater are better choices for those climates.

The exception is point of use electric units for a single fixture like a bathroom sink or a hand washing station. Those work fine anywhere because the flow rate is low enough that the unit can keep up.

Way more than most people expect. A whole house electric tankless unit typically needs 2 to 3 dedicated 240 volt circuits, each pulling 40 to 50 amps. Add that up and you are looking at 100 to 150 amps just for the water heater.

For context, many older homes have 100 to 150 amp total service. So the water heater alone could max out the entire panel. Even newer homes with 200 amp service will feel the squeeze. You might need a panel upgrade, which costs $250 to $1,500 depending on your area and the scope of work.

The wiring itself needs to be heavy gauge to handle those amps safely. Running new circuits from the panel to the water heater location adds cost, especially if the panel is far from where the unit is being installed.

Before you commit to an electric tankless, have an electrician check your current panel capacity and calculate whether your existing service can handle the load. This step is free or cheap and can save you from a very expensive surprise halfway through the project.

Here is the quick decision tree I use.

Gas tankless: The customer already has natural gas, they want endless hot water, the house has or can get adequate gas line sizing, and they are willing to spend $3,500 to $5,500 installed. This is the right call for most homes in most climates.

Electric tankless: The customer is in a warm climate, has no gas service, only needs point of use hot water, or has a small household with low simultaneous demand. Great for adding hot water to a distant bathroom or a shop sink.

Heat pump water heater: The customer wants the lowest operating cost, has space in a garage or basement (these units need airflow), qualifies for rebates, and does not mind a tank. Heat pumps are 2 to 3 times more efficient than any other option and often qualify for bigger tax credits.

The worst thing you can do is sell a customer something that does not fit their situation. A cold climate electric tankless will generate callbacks. An oversized gas unit in a small condo is overkill. Match the product to the home and the customer will thank you for it.

For a family of four with two bathrooms, you want a unit that can deliver at least 7 to 8 GPM (gallons per minute). Here is how that breaks down.

Two showers running at the same time use about 5 GPM. Add a kitchen faucet or dishwasher and you are at 7 GPM. If you have fancy rain showerheads, bump that up to 8 or 9 GPM because those big heads use 3 to 5 GPM each.

For gas, that means a unit rated around 180,000 to 199,000 BTUs. The Rinnai RU199, Navien NPE 240A, or Rheem RTGH 95 series are all in that range. These are the workhorses for a medium to large family home.

If you are going electric in a warm climate, look for units rated at 8 GPM or higher at a 40 degree temperature rise. In cold climates, you will need an even bigger unit or possibly two smaller ones in parallel. Check the Energy.gov sizing guide for your specific groundwater temperature.

This is easier than it sounds. Two steps.

Step one: figure out your peak hot water demand. List every hot water fixture you might run at the same time and add up their flow rates. A standard shower is 2.5 GPM, a kitchen faucet is 1.5 GPM, and a dishwasher is about 1.5 GPM. If your worst case scenario is two showers plus the kitchen sink, that is 6.5 GPM total.

Step two: calculate your temperature rise. Take your desired hot water temperature (usually 120 degrees) and subtract your incoming groundwater temperature. In Georgia, groundwater might be 65 degrees so you need a 55 degree rise. In Minnesota, groundwater is 40 degrees so you need an 80 degree rise.

Now find a unit that can deliver your required GPM at your required temperature rise. Every tankless unit has a chart showing GPM at different temperature rises. The higher the rise needed, the lower the GPM output.

When in doubt, size up. A slightly oversized unit costs a little more but never leaves you with a cold shower. An undersized unit is a daily frustration.

With the right unit, yes. With the wrong unit, you are in for a very cold surprise.

Two standard showers use about 5 GPM combined. Most mid to large gas tankless units can handle that without breaking a sweat. A 180,000 to 199,000 BTU gas unit delivers 7 to 9 GPM even with a 50 to 60 degree temperature rise. So two showers and a sink? No problem.

Electric is where it gets tricky. In warm climates with 70 degree groundwater, a good electric tankless can handle two showers. In cold climates with 40 degree groundwater, the same unit might only push 3 to 4 GPM, which is barely enough for one shower plus a trickle.

The other factor people forget is distance. If the tankless unit is in the basement and the two showers are on the second floor at opposite ends of the house, you will have longer wait times and some temperature fluctuation. A recirculation pump ($200 to $700 installed) helps solve this by keeping hot water circulating in the pipes.

Size the unit for simultaneous use, not average use. Murphy’s Law says everyone showers at the same time.

For most homes, one properly sized unit is all you need. A single 199,000 BTU gas tankless delivers 8 to 10 GPM, which handles 3 to 4 fixtures running at once. That covers 90 percent of households.

But for large homes with 4 or more bathrooms, high demand fixtures like rain showers and soaking tubs, or multiple generations living under one roof, two units in parallel start to make sense.

The parallel setup doubles your flow rate. Two mid size units giving you 6 GPM each means 12 GPM total. That is enough for a small hotel. Many brands like Navien and Rinnai are designed for easy parallel installation with built in communication between units.

The downside is cost. Two units, two sets of venting, two sets of gas connections, and more labor. You are looking at $6,000 to $10,000 or more installed. The other option is one large unit plus a point of use electric unit at a distant fixture like a guest bathroom. That is often cheaper and simpler than a full parallel setup.

Talk to your plumber about your actual peak demand before committing to two units. Sometimes the answer is better fixtures, not more heaters.

Commercial and multi unit sizing is different from residential because you have to plan for worst case simultaneous demand from multiple tenants. Nobody coordinates shower schedules in an apartment building.

Start by counting the total hot water fixtures across all units and applying a diversity factor. Not everyone uses hot water at the exact same moment, but in a 4 unit building you might have 2 to 3 showers running at peak times. That is 5 to 8 GPM of simultaneous demand.

For a small multi unit building, parallel tankless units are usually the way to go. Two or three 199,000 BTU gas units in parallel can deliver 20 plus GPM. Some brands offer commercial rack systems designed exactly for this.

Gas line sizing is critical on commercial jobs. You may need a dedicated one inch or larger gas line from the meter. The permit requirements are also stricter and the inspection process is more thorough.

Price these jobs with healthy margins because they take longer to scope, longer to install, and have more moving parts than residential work. Use a detailed estimating tool like Handoff to build accurate bids on complex jobs.

Probably. This is the single most common upgrade on a tank to gas tankless conversion and the one that surprises homeowners the most.

Your old tank water heater used about 30,000 to 50,000 BTUs. A gas tankless unit needs 150,000 to 199,000 BTUs. The half inch gas line that was fine for the old tank simply cannot deliver enough gas volume for the tankless unit at full demand.

The fix is upgrading to a three quarter inch line from the gas meter to the unit, or at least from the nearest adequately sized branch. If the meter is close, this might only cost $300 to $600. If the plumber has to run a new line 50 feet through the house or across the yard, you could be looking at $1,000 to $2,000.

Some homes have a three quarter inch main line already. In that case, you might just need a short section of three quarter inch from the branch to the unit. Your plumber should calculate the gas line capacity using the total BTU demand and pipe length. Skipping this step is one of the most common installation mistakes out there.

Maybe. It depends on what you already have and what else is pulling power in your home.

A whole house electric tankless draws 100 to 150 amps. If your home has a 200 amp panel and you are not running a bunch of other heavy loads like an electric dryer, electric stove, pool pump, and central AC all at once, you might have enough room. An electrician can do a load calculation to find out.

If your home has 100 or 150 amp service, a panel upgrade is almost certainly needed. That runs $250 to $1,500 depending on your area and the complexity. In some older homes, it also means upgrading the service entrance from the utility, which can add even more cost and time.

You also need 2 to 3 dedicated 240 volt circuits from the panel to the water heater. These need to be run with heavy gauge wire (usually 8 AWG or 6 AWG) on their own breakers. Budget $200 to $500 per circuit for the wiring work.

This is why many plumbers recommend gas over electric. The electrical infrastructure costs can eat up the savings from the cheaper electric unit.

If you have hard water, a softener is not required but it is strongly recommended. Hard water is the number one enemy of tankless water heaters.

Here is what happens. Hard water leaves mineral deposits (mostly calcium and magnesium) inside the heat exchanger. Over time, that scale builds up and reduces the unit’s efficiency. Eventually it can cause error codes, reduced flow, and even premature failure. The heat exchanger is the most expensive part to replace.

Most manufacturers like Navien and Noritz recommend water hardness below 11 grains per gallon for their units. If your water is harder than that, they strongly suggest a softener. Some warranty claims have been denied because of scale damage in hard water areas.

A water softener costs $500 to $2,500 installed. That is a chunk of money, but it protects a $1,000 to $2,500 unit and extends its life significantly. At minimum, you should be flushing the unit with vinegar once a year if you have any hardness at all. A softener just means you worry about it less.

If you want happy customers and zero callbacks about billing, put everything on paper from the start. Here are the items that catch homeowners off guard.

Gas line upgrade: $300 to $2,000. Most homes need this and most homeowners have no idea. Call it out clearly.

Venting: $200 to $800. New penetration through an exterior wall or roof is not optional on gas units.

Electrical work: Even gas units need an outlet. Electric units need heavy circuits. Get an electrician quote and include it.

Condensate drain: $100 to $300 for condensing units. Someone has to pipe that acidic water to a drain.

Permits and inspection: $50 to $300. Required in most areas. Do not skip it.

Old unit removal and disposal: $100 to $500. A 50 gallon tank full of water weighs over 400 pounds.

The best practice is a line item quote with every possible cost listed. If something turns out to not be needed, the customer feels like they saved money. If you lowball and then add charges later, trust is gone. A clean quoting process using a tool like QuoteIQ keeps everything transparent.

Think of it less like a water heater swap and more like a small remodel. Here is the reality checklist.

First, your gas line probably needs upgrading. This is the most common surprise. Budget $300 to $2,000 for this alone.

Second, you need entirely new venting. The old vent pipe from your tank cannot be reused. A new vent run through the wall or roof is required for any gas tankless unit.

Third, the unit goes on the wall instead of sitting on the floor. That means finding a good wall location near gas, water, electric, and an exterior wall for venting. Sometimes the best spot is not where the old tank was.

Fourth, permits are usually required. Skipping them can cause problems if you sell the house later.

Fifth, expect the total project to cost $3,500 to $6,000 for a straightforward gas conversion. Complex situations with long gas line runs or difficult venting can push that to $8,000 or more.

Get at least two quotes and make sure each one includes a full line item breakdown. Compare apples to apples, not lump sums.

You need new venting. This is non negotiable and here is why.

Traditional tank water heaters use natural draft B vent, which is double wall aluminum that relies on the heat of the exhaust to rise naturally. Tankless units use powered exhaust fans that push the combustion gases out under pressure. Those gases are also more acidic, especially on condensing models.

Non condensing tankless units require Category III stainless steel venting. This is a special sealed vent system that handles the positive pressure and higher temperatures. Using old B vent would be a code violation and a carbon monoxide risk.

Condensing tankless units use PVC or CPVC venting because their exhaust temperature is much lower (around 100 to 130 degrees). PVC is cheaper and easier to work with, which is one reason condensing units sometimes cost less to install even though the unit itself costs more.

The good news is that many tankless units can vent horizontally through a side wall instead of vertically through the roof. This is often easier and cheaper than running a new vertical vent, especially in a retrofit. Your contractor should evaluate both options and go with whatever makes the most sense for your home.

Half inch water lines will technically work with most tankless units since the connections are usually three quarter inch at the heater and then reduce to your existing plumbing. But “technically works” and “works well” are two different things.

Half inch lines restrict flow. If you are running multiple fixtures at the same time, the flow rate through those small pipes may not be enough to keep the tankless unit happy. Some units have minimum flow requirements to activate. If the flow drops below that threshold, the unit shuts off and you get a blast of cold water.

You probably do not need to re pipe the entire house. But upgrading the main supply line from the tankless unit to three quarter inch for the first 10 to 20 feet makes a noticeable difference. From there, the half inch branches to individual fixtures are usually fine.

If your house is old enough to have galvanized steel pipes, the interior of those pipes is likely corroded and the actual inside diameter is even smaller than half inch. In that case, re piping at least the main runs is worth considering as part of the project.

The key word here is transparency. These jobs have a lot of moving parts and the customer needs to see where every dollar goes.

Build your quote with clear line items. Unit cost. Labor for mounting and plumbing. Gas line upgrade as a separate line. Venting as a separate line. Electrical as a separate line. Removal of the old tank. Permits. Every item gets its own number.

For the gas line, measure the run and quote accordingly. A 10 foot run from an existing three quarter inch branch is very different from a 50 foot run back to the meter. Do not guess.

For venting, determine if you are going through the wall or through the roof. Wall vents are usually $200 to $500. Roof vents can be $400 to $800 depending on the height and obstacles.

If you are subbing out the electrical, get the electrician’s number before you present the quote. Rolling it all into one package is cleaner for the customer.

Tools like QuoteIQ and Handoff are built for exactly this type of multi trade quote. They help you look professional and make sure nothing gets left out.

This is one of the most confusing topics for homeowners, but it is actually straightforward once you know the basics.

A non condensing unit runs at about 80 to 85 percent efficiency. The exhaust gases come out hot (around 300 degrees) and need expensive stainless steel venting that can handle that heat. These units are cheaper to buy but the venting costs more.

A condensing unit runs at 90 to 98 percent efficiency. It has a secondary heat exchanger that pulls extra heat out of the exhaust. The result is cooler exhaust (around 100 to 130 degrees) that can be vented through regular PVC pipe. Much cheaper venting, but the unit costs $300 to $800 more.

The catch with condensing units is they produce acidic condensate water that needs to drain somewhere. You need a condensate drain line and sometimes a neutralizer kit to prevent the acid from eating through drain pipes. That adds $100 to $300 to the install.

When you add up unit cost plus venting cost plus drain cost, condensing and non condensing installations often end up costing about the same total. But condensing gives you better efficiency and lower monthly bills. For most new installs, condensing is the smarter long term choice.

Yes, and for many installations this is actually the preferred method. Most tankless water heaters use powered exhaust fans that push the combustion gases out, so they do not need to rely on the natural upward draft that a vertical vent provides.

Horizontal venting through a side wall is usually easier and cheaper than going through the roof. You cut one hole in an exterior wall, run the vent pipe a short distance, and you are done. No flashing on the roof, no long vertical pipe runs, no worrying about the vent getting blocked by snow or debris.

There are some rules though. The vent termination has to be a certain distance from windows, doors, air intakes, and property lines. Code requirements vary by area, but a common minimum is 4 feet from a window or door and 3 feet above any forced air intake. Your contractor needs to check local code.

The vent also cannot terminate in an enclosed area like a porch or under a deck where exhaust gases could build up. And some HOAs have rules about visible vent terminations on certain sides of the house. Check before you drill.

Clearance requirements are set by local building codes and the manufacturer’s installation manual. Both matter, and whichever is stricter wins.

General guidelines from most codes and manufacturers include keeping the vent termination at least 4 feet horizontally from any window, door, or opening that can be opened. It should be at least 12 inches above the ground and 3 feet above any forced air intake within 10 feet. Most codes also require 4 feet from any gas meter or regulator.

If the vent terminates near a sidewalk or area where people walk, it needs to be high enough that the hot exhaust does not hit anyone. Some codes require 7 feet of clearance above walkways.

The reason this matters is safety. Tankless exhaust contains carbon monoxide. If that exhaust gets pulled back into the house through a nearby window, it is dangerous. Inspectors take vent clearances seriously and a failed inspection means rework.

Pro tip for contractors: take a photo of the proposed vent location with a tape measure showing clearances before you start cutting. If there is ever a question during inspection, you have documentation. It takes 30 seconds and can save hours of headaches.

The vent material depends on the type of unit. Get this wrong and you are looking at a code violation, a safety hazard, or both.

Condensing tankless units produce cool exhaust (100 to 130 degrees) and use Schedule 40 PVC or CPVC venting. This is cheap, easy to work with, and widely available.

Non condensing tankless units produce hot exhaust (300 plus degrees) and require Category III stainless steel venting. This is more expensive and harder to find at your local hardware store, but it is the only material rated for those temperatures.

What happens if you use PVC on a non condensing unit? The heat melts and warps the PVC. At best, you get a vent failure and a red tag from the inspector. At worst, you get combustion gases leaking into the living space. There are documented cases on the NACHI inspector forum of exactly this happening.

What about using stainless on a condensing unit? It works, but you are wasting money. The acidic condensate in a condensing exhaust can actually corrode some stainless vent materials faster than PVC handles it. Always follow the manufacturer’s vent specification for the specific model you are installing.

In most cities and counties, yes. A water heater installation requires a plumbing permit, and if gas or electrical work is involved, you may need additional permits for those trades.

The permit itself usually costs $50 to $300. The process involves pulling the permit before the work starts, doing the installation, and then scheduling an inspection. The inspector checks that everything meets code, including venting clearances, gas line sizing, electrical connections, and the condensate drain.

What happens if you skip it? A few things, none of them good. If your insurance company finds out the water heater was installed without a permit and something goes wrong, they may deny the claim. If you sell the house, a home inspector will flag the unpermitted work. The buyer may demand you get it permitted or ask for a price reduction.

In some areas, the city can fine you for unpermitted work and require you to open up walls so an inspector can see the connections. That is way more expensive than just getting the permit in the first place.

Bottom line: get the permit. It costs a little bit and protects you a lot.

Code requirements vary by state and city, but here is what most jurisdictions are looking at during an inspection.

Gas line sizing: The gas line must be large enough to supply the unit’s maximum BTU rating at full flow. This means calculating the total length of the gas run and verifying the pipe diameter is adequate. Most codes reference the International Fuel Gas Code tables for this.

Venting: The vent must be the correct material and size per the manufacturer’s specs. Clearances from windows, doors, and air intakes must meet code minimums. The vent must terminate outside, never into an attic or crawl space.

Condensate drain: Condensing units need a drain for acidic condensate. Many codes require a neutralizer cartridge before the drain ties into the plumbing system.

Seismic strapping: Required in earthquake zones, particularly California. The unit must be strapped to the wall with approved seismic brackets.

Other items inspectors check include a sediment trap on the gas line, a shutoff valve on the gas and water lines, proper electrical connections, and adequate clearance from combustible materials. Check with your local building department before starting the job. Many jurisdictions publish checklists online that spell out exactly what they want to see.

Yes, and it happens more often than you would think. Home inspectors look for water heater installations that were done without permits, and they know the signs.

If the buyer’s inspector flags your tankless install as unpermitted, a few things can happen. The buyer might ask you to get it permitted and inspected before closing, which means hiring a contractor to bring everything up to current code. They might ask for a price reduction to cover the cost of fixing it. Or in some cases, they might walk away from the deal entirely.

There have been stories on Reddit about homeowners who had to spend thousands retroactively permitting a water heater install that would have cost a couple hundred dollars in permits originally. The worst cases involve opening up walls so the inspector can verify the gas line, venting, and connections.

The title company and the buyer’s lender may also flag unpermitted work. Some lenders will not finance a home with known unpermitted modifications. It is a headache you do not want at closing time. Spend the $100 to $300 on the permit and sleep easy.

The $100 per year number comes from ENERGY STAR, which estimates about $95 in annual savings for a gas tankless unit compared to a standard gas tank. That number is based on typical household usage of about 64 gallons per day.

Is it realistic? For an average family, yes. Some families save more, some save less. A family of five that burns through hot water will save more than a single person who takes short showers. Your local gas or electric rates matter too. If energy is expensive in your area, the dollar savings are higher.

The Department of Energy puts the efficiency improvement at 24 to 34 percent for homes that use 41 gallons or less per day. For homes using more than 86 gallons per day, the savings drop to about 8 to 14 percent because the unit runs so much that the “on demand” advantage shrinks.

The honest answer: expect to save somewhere between $50 and $150 per year. Over the 15 to 20 year life of the unit, that adds up to $750 to $3,000. Nice, but not life changing. The real benefit is endless hot water and a unit that lasts twice as long.

Good question, and the answer is yes, tankless is genuinely more efficient, but the savings are not as dramatic as some people claim.

The biggest efficiency advantage of tankless is eliminating standby heat loss. A tank water heater keeps 40 to 50 gallons of water hot 24 hours a day, even when nobody is home. That constant reheating accounts for about 20 to 30 percent of a tank’s energy use. Tankless units only fire when you open a hot water faucet, so that standby waste disappears.

Now about pilot lights. Older tankless models had standing pilot lights that burned gas continuously. Modern units use electronic ignition, so the pilot light issue is basically gone. There is a small amount of standby electricity for the control board (about 2 to 5 watts), but that costs maybe $5 to $10 per year. Not enough to worry about.

The one situation where efficiency gains shrink is if you use a lot of hot water. If the unit is running constantly during peak times, it is not much different from a tank that is always reheating. The biggest savings go to households with moderate usage and long idle periods between uses.

For pure energy savings, heat pump water heaters win. They are 2 to 3 times more efficient than any other type of water heater because they move heat from the surrounding air into the water instead of generating heat from scratch.

A heat pump water heater can cut your water heating costs by 50 to 70 percent compared to a standard electric tank. That is significantly more savings than the 24 to 34 percent you get from going tankless. The federal tax credit is also more generous for heat pumps, up to $2,000 versus $600 for tankless.

So why does anyone buy tankless? Because heat pumps have trade offs. They are big (they look like a tall tank with a unit on top), they need about 1,000 cubic feet of airflow, they cool the room they are in (great in summer, not great in a cold basement in winter), and they can be slow to recover during heavy use. They also produce some noise.

Tankless gives you unlimited hot water on demand in a compact wall mounted package with no airflow requirements. Heat pump gives you the lowest energy bills but with a bigger footprint and some quirks. It depends on what matters more to you.

Keep it simple or you will lose them. Here is a quick method that works for most residential conversations.

Step one: Find their current annual water heating cost. For gas, the average household spends about $250 to $420 per year heating water with a tank. For electric, it is about $400 to $600 per year. If they know their actual utility bill breakdown, even better.

Step two: Apply the savings percentage. Tankless saves roughly 25 to 30 percent on water heating for most homes. So if they spend $400 per year on gas water heating, tankless saves about $100 to $120 per year.

Step three: Multiply by the unit’s lifespan. A tankless unit lasts 15 to 20 years, so $100 per year times 15 years equals $1,500 in lifetime savings. Compare that to the extra cost over a tank replacement.

Add in the federal tax credit ($600 for qualifying models) and any local rebates, and the numbers start looking better. Present it on a simple one page estimate. The customer does not need a spreadsheet. They need to see: “This costs more today, but saves you this much over time.” A clean estimate from a tool like QuoteIQ makes this easy to present.

Once a year is the standard recommendation. If you have very hard water (above 11 grains per gallon), every 6 months is better. If you have a water softener, you can stretch it to every 12 to 18 months.

And yes, you can absolutely do it yourself. It is one of the easier home maintenance tasks once you know the steps. You need a small submersible pump, two hoses, a 5 gallon bucket, and about 2 to 3 gallons of white vinegar. That is it.

Close the isolation valves on the hot and cold water lines. Connect the pump and hoses to the service ports. Pour the vinegar in the bucket, turn on the pump, and let it circulate through the unit for 45 to 60 minutes. The vinegar dissolves the mineral scale inside the heat exchanger. Flush with clean water when done. The whole process takes about an hour.

If your unit does not have isolation valves and service ports, you should have those added. They cost about $100 to $200 to install and make flushing possible without calling a plumber every time. Most good installers include them as standard.

It will not explode or anything dramatic. But it will slowly get worse and eventually cost you a lot of money.

Here is what happens. Mineral scale builds up inside the heat exchanger, which is the part that actually heats the water. As the scale gets thicker, the unit has to work harder to heat the same amount of water. Your energy bills creep up. The water temperature becomes inconsistent. You might notice the unit cycling on and off or throwing error codes.

After a few years of zero maintenance in hard water, the heat exchanger can get so clogged that the unit shuts itself down with a scale detection error. At that point, a professional descaling might fix it. Or the heat exchanger might be damaged beyond cleaning and need replacement. A new heat exchanger costs $400 to $800 plus labor. That is almost as much as a new unit.

There are plenty of cautionary tales on r/HomeImprovement from homeowners who skipped flushing for 5 years and ended up replacing a $1,500 unit. One hour of maintenance per year is cheap insurance. Do not skip it.

This is one of the strongest selling points for tankless. The Department of Energy says tankless water heaters last 20 years or more with proper maintenance. Traditional tank models last about 8 to 12 years before the tank rusts out.

That means over a 20 year window, you will probably replace a tank water heater at least once, maybe twice. A tankless unit bought today could still be running in 2046. That is a long time for a household appliance.

The key phrase is “with proper maintenance.” A tankless unit that never gets flushed in hard water might only last 10 to 12 years, which is not much better than a tank. Annual descaling keeps the heat exchanger clean and extends the life dramatically.

Most parts on a tankless unit are replaceable too. If the igniter, flame sensor, or flow sensor fails after 10 years, a plumber can swap it for $100 to $300 in parts and labor. On a tank water heater, once the tank starts leaking, the whole thing goes to the dump.

When you factor in the longer lifespan, the higher upfront cost of tankless starts to look more reasonable on a per year basis.

Service agreements are great recurring revenue for plumbing companies. Here is what a solid annual tankless maintenance visit should include.

Descale the heat exchanger using a vinegar or commercial descaling solution. This is the core of the visit and takes about 45 minutes to an hour.

Clean or replace the inlet water filter. Most tankless units have a small screen filter that catches sediment. It takes 2 minutes to clean and makes a big difference.

Inspect the burner and flame rod (gas units). Look for soot, corrosion, or discoloration that indicates combustion problems.

Check the vent system for blockages, corrosion, or loose connections. Make sure the termination cap is clear of debris, nests, or ice buildup.

Test the water temperature at the nearest fixture to make sure it matches the set point. Check for error codes in the unit’s history log.

Inspect the condensate drain (condensing units) for clogs or leaks. Check the neutralizer cartridge and replace if needed.

Most plumbing companies charge $100 to $200 per annual visit. Offering a service plan at $150 per year is easy to sell and builds long term customer relationships. Track your service agreements in a CRM like GoHighLevel to automate reminders and never miss a renewal.

This is the question that starts arguments on plumbing forums. Everyone has a favorite and they will defend it like a football team. Here is what the consensus looks like across r/askaplumber and trade forums.

Rinnai is the old reliable. They have been in the tankless game longer than most and their units are known for durability. Parts are widely available and most plumbers know how to work on them. They are also the most expensive. A Rinnai RU199 runs about $1,500 to $2,000 for the unit alone.

Navien is the value champion. Their NPE series condensing units are priced lower than comparable Rinnai models and they offer the best warranty in the business at 15 years on the heat exchanger. Navien also includes a built in recirculation pump on many models, which saves you $200 to $700 on a separate pump. Many plumbers say Navien has the best technology for the price.

Rheem is the budget friendly option. Their units are solid and widely available at big box stores. They are a good choice for straightforward replacements. The downside is some plumbers find the tech support and parts availability slightly behind Rinnai and Navien.

All three brands make reliable units. You will not go wrong with any of them.

Warranties vary a lot between brands, and what they cover matters more than how long they last. Here is the breakdown.

Navien leads with a 15 year warranty on the heat exchanger, 5 years on parts, and 1 year on labor. That 15 year heat exchanger coverage is the longest in the industry and a big reason plumbers recommend them.

Rinnai offers a 12 year heat exchanger warranty (residential), 5 years on parts, and 1 year on labor. Solid coverage for a premium brand.

Rheem sits at about 12 years on the heat exchanger for their higher end models and 5 years on parts. Their entry level models have shorter coverage.

Here is the fine print that matters. Most warranties require professional installation by a licensed contractor. DIY installs can void the warranty. Most also require annual maintenance, and some require proof of maintenance to honor a claim. Hard water damage is often excluded, which is why a water softener or regular descaling is important.

Labor coverage is almost always limited to the first year. After that, you pay for the plumber’s time even if the part itself is covered. When comparing brands, look at the heat exchanger coverage first since that is the most expensive part to replace.

This is the kind of question that gets honest answers on trade forums because contractors have nothing to gain from brand loyalty except fewer headaches.

For ease of service, Rinnai and Navien are the most commonly praised. Both have clear diagnostic codes, well documented service manuals, and straightforward access to internal components. If something goes wrong, you can usually diagnose and fix it on the first visit.

For parts availability, Rinnai has a slight edge because they have been in the US market longer and have a wider distribution network. Most plumbing supply houses stock Rinnai parts. Navien parts are catching up fast but some contractors in rural areas report longer wait times.

For fewest callbacks, the consensus on r/askaplumber leans toward Navien and Rinnai in roughly equal measure. Both brands are well engineered and reliable when installed correctly. Rheem gets more mixed reviews, though their newer models have improved significantly.

Whatever brand you choose, standardize on it. Stocking parts for one or two brands instead of five simplifies your truck inventory and speeds up service calls. Track your callbacks and parts usage in a field management tool like Contractor Plus to see which units actually perform best in your market.

The cold water sandwich is one of the most common complaints from tankless owners, and it is not a defect. It is just how tankless units work.

Here is what happens. Someone finishes a shower and turns off the hot water. The tankless unit shuts off. But there is still hot water sitting in the pipes. A few minutes later, someone else turns on the hot water. They get that leftover hot water first, then a slug of cold water (the water that was sitting between the unit and the faucet), and then fresh hot water once the tankless fires up and heats it. Hot, cold, hot. That is the sandwich.

It usually only lasts 10 to 30 seconds, but it is annoying. There are a few ways to deal with it.

A recirculation pump ($200 to $700 installed) keeps hot water moving through the pipes so there is no cold slug waiting. Some tankless models like certain Navien units have a built in recirculation pump, which is a nice bonus.

A small buffer tank (2 to 5 gallons) installed after the tankless unit absorbs those temperature swings and delivers consistent hot water. This adds $200 to $400 to the project.

Or you can just wait 15 seconds. It is mildly annoying but not a deal breaker for most people.