Tankless Water Heaters

The Homeowner’s Guide to Tankless Water Heaters

Did you know the modern water heater was invented in Pittsburgh, PA, during the 1800s?

Before the invention of the water heater, people heated water on the stove and poured it into a bath. The evolution of the water heater continues with manufacturers working continuously to build better, more efficient appliances. With an average lifespan of 6-12 years, a new water heater may be a purchase you’ll make soon.

While conventional tank water heaters are the most common, tankless water heaters are growing in popularity. In this guide, you’ll find all the information you need to decide which type of water heater best suits your needs.

How Does a Tankless Water Heater Work?

If you’ve only used the conventional tank water heaters, you’ll find the tankless water heater operates much differently. First, tankless water heaters don’t hold water in a tank. They also don’t heat water 24/7 (conventional tank water heaters do), which is one of their energy-saving features. Instead, the water heater works on demand when someone turns on the tap, the shower, or a water-using appliance.

Here’s a step-by-step example of how a tankless water heater works:

Turn the hot water tap on
Cold water enters the water heater
Water flow sensors detect water flow
Sensors trigger an internal computer
Computer ignites the burner or electric heating element
Water circulates through the heat exchanger
Water reaches the designated temperature
Hot water exits the water heater and travels through your pipes
Once the demand for hot water no longer exists, the water heater shuts down.

Does a Tankless Water Heater Take Up More Space?

Those 40–60-gallon conventional tank water heaters have a large footprint. They take up a lot of space, and these water heaters must also be installed in a secure area with proper ventilation. Imagine the extra space you could enjoy if you didn’t need to set aside a dedicated area in the basement or a utility closet. If you go tankless, you can hang the water heater on the wall. You might even hang it in the garage if you live in a warm climate.

Say “good-bye” to the bulky tank and “hello” to the sleek, compact design of the tankless water heater. How does a water heater the size of a suitcase sound? These water heaters are so compact you can even mount them in a cabinet under the kitchen or bathroom sink. However, they’re not designed to sit on the floor like a tank water heater.

Is a Tankless Water Heater More Energy Efficient?

American households average $114.44 per month for electricity and $63.34 for natural gas. In the current economy, utility costs are expected to continue rising. Tank and tankless water heaters operate on either gas or electricity, but one uses energy more efficiently.

A tankless water heater uses up to 34% less energy than a tank storage water heater. Gas-fired tank water heaters are more efficient than electric tank units. There is a caveat. For your tankless water heater to use 34% less energy, your household must use 41 gallons or less of hot water daily. If your hot water use is closer to 86 gallons a day, efficiency drops to 14% less energy.

But there’s more.

When comparing gas-powered vs. electric tankless water heaters, the electric unit will operate more efficiently. It’s because the gas water heater uses a continuously burning pilot light, which may waste energy. This cancels out any energy savings. A better energy-saving solution is to install a tankless unit with an intermittent ignition device (IID). The IID only switched on when needed. If you’re intent on maximizing your energy savings, consider installing one tankless water heater at each water point. You may reduce your energy use by up to 50%.

Are Tankless Water Heaters Environmentally Friendly?

In 2019, the United States emitted 5,130 million metric tons of energy-related carbon dioxide. The rest of the world released a combined 33,621.5 million metric tons. To be fair, most of the emissions in the U.S. come from corporations, power plants, and non-renewable energy use. The average person can do nothing about that, but you can reduce your carbon footprint by being more conscious of how you use energy. If you evaluate whether a water heater puts a strain on the environment by its energy use, a storage water heater isn’t the most eco-friendly solution. Due to standby heat loss, an electric tank unit powered uses two times more electricity than a tankless water heater.

Here’s how it works:

You turn on the hot water tap. The system heats the water. If you don’t use it, the water sits in the tank and slowly loses heat. When you need hot water again, the water heater uses even more energy. It’s like double-dipping.

An electric tankless water heater eliminates the problem of excessive energy use. There’s no storage tank full of water that needs constant energy to heat and re-heat water. Instead, thermal optic sensors heat the water. They only activate when they sense water passing through—hot water on demand. Any appliance that needs less energy to operate is good for the environment, but you should consider another feature of tankless water heaters.

They’re nearly 100% recyclable. They also last longer than conventional storage tank units. Less waste in landfills—where old water heaters go to die—makes them an excellent environmentally-friendly solution to providing hot water for your household.

Does a Tankless Water Heater Last Longer Than a Conventional Water Heater?

Above, you read that tankless water heaters last longer than storage tank units. Let’s explore that more. At the beginning of this article, we noted that conventional tank water heaters last around 6-12 years. Tankless water heaters last 20-30 years. Because they have replaceable parts, you can usually extend their service life by several more years than you could with a conventional tank model. The primary reason they last longer is they don’t store mineral-filled water. Over time, and especially if you have hard water, mineral buildup in a tank unit can corrode the interior. Storage water heaters also bake scaly buildup on the bottom of the unit, which reduces efficiency and eventually causes the unit to rust.

You’ll still need to take steps to prevent issues caused by minerals in your water, but with proper maintenance, a tankless water heater will likely be the last one you ever buy.

To maximize longevity for a water heater, it’s a good idea to schedule regular maintenance with your plumbing company.

Does a Tankless Water Heater Have a Better Flow Rate?

With a tank water heater, the size of the tank limits how much hot water you have available at any given time. Regardless of tank size—and type of water heater— there’s no such thing as limitless hot water. A tankless water heater relies on flow rate to maximize hot water availability. Flow rate is the gallons per minute (GPM) of hot water the unit can deliver. Tankless units heat water as you use it, so there is a limit to how much water it can heat at any one time. It would be best to consider the flow rate when buying a tankless model for your home. To gain some perspective, let’s look at how much water you use for showering and washing dishes and clothes.

Standard shower heads – 2.5 GPM
Sinks – 2.5 GPM.

Not many people limit shower time to a few minutes unless they’ve learned to enjoy military showers. Most people shower for roughly 8 minutes and use 17 gallons of water at 2.1 GPM (with a water-saving showerhead). Your washing machine uses between 20-40 gallons per load. Top loading machines use more water than front loaders. Dishwashers use 7-10 gallons per load. The maximum flow rate for tankless water heaters ranges between 2-5 GPM. Gas units offer a better flow rate than electric models. If your household uses several different fixtures or water-using appliances at the same time, you’ll want a unit with a GPM higher than 2.

FYI: If you compare tank and tankless water heaters, it’s almost like comparing apples and oranges. The concern when buying a tank water heater is the first-hour rating (FHR). FHR refers to how much hot water the tank produces in one hour when fully heated.

Are There Common Issues or Fixes Needed with a Tankless Water Heater?

All water heater types come with potential issues; tankless units included. Here are the most common problems people face after installing a tankless water heater:

Mineral Buildup

Calcium and Magnesium can cause scaly buildup. Debris can also build up quickly if you have well water. To avoid mineral buildup, flush your water heater every six months. Installing a home water softener will also help slow mineral buildup. Check the water filter often to prevent debris buildup.

Ignition Failure

A problem with your natural gas supply is often the cause of ignition failure. Partially opened gas valves or water valves can also cause failure. Check your propane supply. Make sure you’ve paid your gas bill. Ensure valves are open. If you still have ignition problems, you may need a replacement part.

Flame Failure

A problem with gas pressure or an electrical issue can cause flame failure. Insufficiently sized gas lines, combustion issues, or regulator failure are other possible causes.

Air Supply or Exhaust Blockage

You’ll likely know when you have a blocked air supply or exhaust. Tankless water heaters have a display that shows error codes. Air or exhaust blockage is a problem with combustion or venting. You can troubleshoot by inspecting vent pipes. Look for holes or loose connections.

Tip: Rodents, birds, and wasps love to make nests in vent pipes.

System Overload

You’ll know you have an issue with system overload if your water heater struggles to deliver hot water or completely shuts down. Try reducing demand. If system overload becomes a consistent problem, you may need to upgrade to a larger unit. There is one more issue some people face when using tankless water heaters. It’s called a cold-water sandwich. Read on to learn more.

What Is a Cold-Water Sandwich?

If you’ve ever started your shower with warm water only to get a cold blast for several seconds followed by a gradual warm-up, you’ve tasted a cold-water sandwich. Here’s what happened:

Someone else in your household took their shower first. When they finished, a small amount of hot water remained in the pipes between the water heater and the shower. When you began your shower, you got the leftover or trapped water, so it was still warm. The cold-water blast usually lasts a few seconds before you start feeling warm water again. You can do nothing to prevent the cold-water sandwich other than wait to jump in the shower until the water heater has time to deliver more heated water.

Tankless Water Heater Types

When you’re ready to install a new water heater, you’ll find several different types of hot water tanks. Tankless water heaters come in gas, electric, or solar-powered models. You can also choose between a condensing or non-condensing unit.

Non-Condensing

Most gas-fired tankless water heaters are non-condensing models. Usually, people new to using tankless water heaters go with a non-condensing unit because they can use existing ventilation. Here are few key features to consider:

Uses heat exchangers to heat water

Vents the exhaust outdoors

Requires stainless steel flue pipes

Condensing

Condensing water heaters use less energy and waste less water. Installing a condensing unit may qualify you for a federal tax credit. Features also include:

Extracts heat from the exhaust and then releases it into the venting system
No need for flue pipes or venting materials
Use extracted heat as an additional resource to heat water

Generally, condensing tankless water heaters cost more upfront than non-condensing units. Their lower installation costs and higher energy efficiency mean you pay less overall.

Pros and Cons of Tankless Water Heaters

Each type of tankless water heater has pros and cons you’ll want to consider before committing. Here are a few things to consider when deciding between gas and electric tankless units.

Gas Model Pros

Gas-fueled tankless water heaters heat water more quickly than electric models. They make a sensible choice if you live in an area where natural gas and propane cost less than electricity.

Gas Model Cons

You may pay less for a gas model, but the cost to install it will be higher than an electric model. Gas units require more maintenance. The control panel relies on electricity, so in a power outage, you won’t have hot water.

Electric Pros

You can installed an electric tankless water heater just about anywhere. Because there’s no combustion, you won’t need a ventilation system. Electric models also cost less to install.

Electric Cons

Electric tankless water heaters have a slower heat and recovery rate, so they take longer to deliver hot water. Electric tankless models draw a lot of power—120 to 160 amps—so, you may need to upgrade your electrical panel.

Your plumber can share more information on the pros and cons of each type of water heater. They can also talk about new water heater regulations.

Is a Tankless Water Heater More Expensive?

There are many different tankless water heater types, and each one has features and benefits that affect the price. The cost of demand water heaters varies based on this and several other factors, including:

Fuel type
System size
Additional wiring or piping
Upgrades

The initial cost may seem high compared to a conventional tank storage water heater. However, the energy savings will translate into saving money over the long term. Most people feel the savings benefits of installing a tankless water heater more than justify the cost.

What Is the Average Installation Cost for a Tankless Water Heater?

The average cost to install a tankless water heater is $2,500 to $4,500. Gas-fired models cost around $6,000 for equipment and installation. If you go with the electric model, you’ll pay about $4,000. If you need to install more than one unit—you may need a separate unit at each hot water point—plan on paying about $2,000 for each electric model. Gas models run about $800.  Electric tankless water heaters have a lower installation cost because they can go just about anywhere and don’t need an additional fuel line. Generally, electric models are less complicated to install. Gas water heaters require more work to install. Unless you have a line in a place where you plan to install a gas model, you’ll need to run a gas line. This adds to your costs. Remember, these are average costs. Prices may be different in your area.

A Few More Benefits of Tankless Water Heaters

We’ve already pointed out several advantages to installing a tankless water heater. They take up less space and help save money on energy costs, and they’re an excellent option if you’re passionate about using environmentally friendly appliances. Besides energy and cost savings, there are other benefits when you choose a tankless water heater over a conventional tank-style unit. Tankless water heaters provide an endless supply of hot water. You may need to wait a few minutes for the water to heat up, but you’ll never run out. With a tankless unit, there’s a lower risk of leaking. One in 50 homeowners files claims with homeowners’ insurance providers due to water damage. At least some of those claims come from damages caused by leaky water heaters. Tankless water heaters can be safer than tank models. The absence of a storage tank lessens the risk of leaks or ruptures. You’ll also avoid unpleasant odors that sometimes develop in tank water heaters due to bacteria growth.

Is a Tankless Water Heater Right for Me?

When your water heater goes south, it can feel overwhelming to decide which type of water heater is the right one for you. While your plumber can help you make your final decision, here are a few questions to ask yourself:

Are energy savings a top priority? Go with a tankless water heater because it doesn’t need to work continuously to deliver enough gallons of hot water to satisfy the demand of your household.

Are you looking for long-term savings? Choose a tankless model because the long-term savings can offset the higher initial costs.

Do you use less than 40-50 gallons of hot water per day? The limited flow rates of a tankless unit won’t affect you as much as they would if you use more than 50 gallons. Even if you use a lot of hot water, you can buy a larger unit or install multiple water heaters.

These are just a few questions that may help you determine whether a tankless water heater will be a purchase you’ll feel happy making.

How to Buy a Water Heater

If this is your first water heater purchase, you’re likely wondering what to do first. Do you go to a local home improvement store and pick out the cheapest model? Or do you call a plumber?

Visiting your local big box home improvement or hardware store is an excellent place to start. You can view the different types of water heaters and ask questions. Often retail stores offer special pricing, so why not save a few dollars and buy it from the store? You’ll still need to pay for installation.

On the other hand, when you have a plumbing company order your new water heater, you may also save some money. Sometimes, plumbers extend discounts that aren’t available from stores. They usually offer maintenance plans, which help you extend the life of your water heater.

Another advantage to purchasing a water heater through a plumbing company is that you’ll have a chance to have your questions answered by the expert who will install the unit. Plumbers usually have favorite brands and can help you decide which suits your needs better. Plumbers will often offer better warranties if they provide the heater.

Do All Plumbing Companies Install Tankless Water Heaters?

You might not always think about it, but you rely on your water heater daily. It’s the one appliance that helps keep you and your household clean. If you need a replacement and you’re considering a tankless model, you want a qualified professional to install it. That means calling the right plumbing company. While many plumbers install tankless water heaters, not all are qualified for this type of plumbing work. The expert plumbers at Atomic Plumbing have taken care of plumbing needs—including tankless water heater installation—for Hampton Roads residents since 1968. Contact us today for service.