Boiler vs Water Heater: propane gas vs electric water heater comparison

Everyone needs the most reliable and energy efficient set up with the lowest possible upfront cost when it comes to heating for family needs. If you are not a plumbing professional, it is a good idea to get some advice on boiler vs water heater problem. What is better, propane or hot water heater, tankless or boiler? We’ll help you to make the right choice.


Boiler vs water heater: domestic water heating for showering, bathing and washing

When it comes to heating water for washing, bathing and showering, tank heaters (both electric and gas) are commonly referred to as boilers.

Electric boiler vs water heater (potable water systems)

Electric tankless water heaters are very  compact and efficient devices. They are high power devices, so you do need sufficient power. The main advantage is that tankless heater only makes heated water when you need it. And since it’s compact, you can install it next to the tap and get hot water right away and reduce heat loss in the pipes. There are even models of heaters located directly on the tap.

electric vs gas tankless water heater
EcoSmart Electric Tankless Water Heater

So, electric tankless (also known as point-of-use) WH are small, durable and quick. Their bad is that they need THICK wires with a dedicated breaker. To install the device you need worker with electrical permits and with plumbing permits (2 workers or one expensive certified in both). Tankless units may be very durable, but it depends on the quality of the water. If it’s hard, you have to descale the heater as much as 2x a year.

boiler vs water heater
A.O. Smith electric 40 gal boiler vs water heater

Electric boilers (tank water heaters) consume the same power to heat 1 gallon of water per 1F degree, but they do it slowly and store heated water. Since hot water is stored in the tank, despite the thermal insulation, some thermal energy is lost to heat the air. And due to its large size, you cannot install a tank near each tap. Therefore, the length of the pipes from the heater to the faucets is longer, hot water does not come immediately and additional losses arise in a pipeline. If your boiler isn’t large enough, and you’re showering for a long time, you need to blend hot and cold water few times to get constant temperature. With a tankless water heater you just set the temperature and have no need to blend it.

The advantages of electric boilers are:

  • If the water in your area is hard, they will last way more than the tankless will
  • Typical electric power of boiler is 1-2kW, therefore no special wiring is required
  • Boiler installation will require at least 3-4 hours less working time and $200-300 less in additional material costs

Boiler vs hot water heater: conclusions

If you have space to install a large electric boiler, this is the cheapest and hassle-free solution. Otherwise, install an on-demand heater, the higher cost will pay off over time due to the higher efficiency.

NG or propane tankless water heater vs boiler

Tankless heaters

On-demand (tankless) natural gas or propane water heaters are pretty convenient and reliable. I really like it for several reasons. Similar to electric, gas tankless water heaters make hot water only when you need it. If it is close to the tap, you get hot water almost instantly only having to wait for it to travel through the plumbing.

boiler vs hot water heater
Eccotemp Natural Gas Tankless Water Heater

Gas tankless heaters may be very powerful and work flawlessly for decades. All you need is to flush it annually if your water is hard. For this purpose you can set bypass valves at the outlet and inlet. When you need to flush mineral scale deposits out, you turn off the water in and out, and open bypass valves to flash the heat exchanger with vinegar.

With an on-demand gas heater you have endless hot water. Simpler models don’t modulate the flame and come with a low to high dial so you need to mix the water by the faucets.

propane vs electric water heater
Ridgeyard LPG Heater

The only con is the initial cost. It may be high and depending on the gas service provided, gas tubing may require up-sizing.


electric vs propane tankless water heater
A.O. Smith Gas Water Heater, 40 gal

If the space for placement of a water heater is not a problem and hot water consumption is small, a tank unit may be more economical. They are not dependent on the incoming water temperature, need less maintenance. Usually all you need is to flush out the bottom with a garden hose sometimes.

A boiler heats the water slowly, so it doesn’t have to use a huge flame and doesn’t need big gas pipe. The disadvantages are similar to electric tank units: large size and weight, heat losses, the temperature gradually drops when you use 50% and more of the tank volume, and the hot water volume is limited by the size of the tank.

Tankless water heater vs boiler combo

New combo units have their advantages, and they are efficient, save space and like tankless water heaters can heat water on demand. The only negative is that if it breaks, you have no hot water and radiators are cold too.

So where possible I think you should consider a system with separate devices. For example, am currently dealing with a case with a broken ventor motor on boiler and the customer hasn’t both hot water and heat for two weeks due to poor parts availability. It’s scary to even imagine how unpleasant it would be in the midst of cold weather.

Propane vs electric water heater

For Propane vs electric water heater, it depends largely on relative fuel costs. For example, in Ohio there is no government-subsidized electricity and propane prices vary with time and volumes.

Electric heating is usually more expensive and less desirable unless it comes from the low environmental source as wind or solar. Sometimes consumer don’t consume all the electricity and electric heating can make sense.

Nevertheless, in some areas the electric power is cheap. Considering that the efficiency of electric heaters is very good and heat does not escape through the vents, this might be a good choice. Some electric company even offer a rebate to customers who switch to an electric water heater from a propane unit and it pretty much cover the cost of the water heater. Cost of operation may be about the same when propane prices are high (see also Bradford White vs Rheem Water Heaters Review).


In my opinion, when it comes to gas heaters, the tankless is better than tank. If you are primarily are home beginning and end of day, they help to avoid major standby losses. Gas on-demand units are reliable, long-lasting and inexpensive to maintain. Even if you need need a boiler for space heating, gas tankless heater near the tap is better than combo unit. The distance from where the tank installed usually is too far away from the use points (sinks, etc).

Radiant heating systems – boiler vs water heater

In the context of space heating, a boiler is a device for heating water in closed-loop systems. And some plumbers use domestic water heaters as a boilers.

Water heater advantages

Using a high-quality domestic water heater instead of a boiler helps to save money because it is cheaper. However, there are many other benefits as well.

Boilers are designed to make a lot of hot water for radiators and use large amounts of gas. Heater firebox, chimney and water temperatures are high. On lower temperatures boilers work worse and can even be damaged due to “cold shocking”.

tankless water heater vs boiler
Rinnai Natural Gas Heater

Water heaters are simpler devices with a less heating power. A condensing water heaters, are around 95% to 98% eff. and it is usually much higher than boilers efficiency.

Although water heaters are cheaper and more efficient,you shouldn’t use cheap water heater as a boiler. The heater should have high efficiency, enough heat power and be made of reliable and long lasting materials. High efficiency water heaters doesn’t heed chimney and work with plastic vents. They are also direct vent devices and draw air from the outside of your home for combustion, and this saves money.

Why boilers are still used for heating?

Boilers are high-power devices for space heating. They are designed to be used for this task. For example, Rinnai Tankless Water Heaters are certified to the Standard for Gas Water Heaters ANSI Z21.10.3/CSA 4.3 that includes heaters for use with applications commonly referred to as open loop systems.

Units for use in closed loop systems are certified to the Standard for Gas-Fired Low Pressure Steam and Hot Water Boilers ANSI Z21.13/CSA 4.9 – space heating only (closed loop) systems (see also Rheem vs AO Smith Water Heaters.

These are two different standards and the requirements for these devices are different. For this reason, Rinnai does not recommend the use of its Tankless Heaters for closed loop heating applications and will not honor warranties for units.

Therefore, the using a boiler is a versatile and reliable solution. The use of water heaters for closed loop radiant heating tasks is possible, but requires an understanding of the physics of the process and engineering calculations.

Rinnai RUC98iN Condensing Tankless Water Heater Review

The Rinnai RUC98iN Condensing Tankless Water Heater is designed to not only be an effective alternative to a traditional water heater but is also designed with the understanding that the aesthetics of a home appliance is also important. The Rinnai RUC98iN is one of the most popular models on the tank winning the praise of both customers and plumbing professionals.

What You Should Know About the Rinnai RUC98iN NG Condensing Tankless Water Heater

The Rinnai RUC98iN Condensing Tankless Water Heater offers consumers up to 95% thermal efficiency which also means it also qualifies for Federal Tax Credit. It weighs 71 pounds and can be used with either natural gas or propane.

The Rinnai RUC98iN Condensing Tankless Water Heater allows you to easily get a continuous supply of hot water that can reach temperatures between 98 and 140 degrees Fahrenheit. The unit also comes with a standard digital controller.

The Rinnai RUC98iN is also considered to be among the most durable and sturdy models on the market which is just one ore reason why it is so popular amongst consumers and professionals alike.

Who Should Consider the Rinnai RUC98iN Condensing Tankless Water Heater

The Rinnai RUC98iN Condensing Tankless Water Heater is perfect for anyone who wants to save on their energy bill and make their home more environmentally friendly. This model is one of the most energy efficient models on the market because it employs condensing technology while many of the competing models do not.

The Rinnai RUC98iN NG is also an excellent option if you are looking for a tankless water heater than is able to meet a variety of plumbing demands. This model offers the capacity to be truly versatile while still remaining efficient.

The Benefits of the Rinnai RUC98iN Condensing Tankless Water Heater

The biggest benefit of the Rinnai RUC98iN Condensing Tankless Water Heater is certainly the unique condensing technology it utilizes to make it more efficient. This model also offers adjustable temperature control to better serve your needs.

The Disadvantages of the Rinnai RUC98iN Condensing Tankless Water Heater

The Rinnai RUC98iN Condensing Tankless Water Heater is a bit more difficult to install than other models so you may need a little help getting the water heater in place.

Important Final Words on the Rinnai RUC98iN Condensing Tankless Water Heater

The Rinnai RUC98iN Condensing Tankless Water Heater is one of the most trusted and popular models of tankless water heater available today. Although this model may be a little more difficult to install than some of its contemporaries it is well worth it when you consider the benefits.


Takagi Tankless Water Heaters Review

The Takagi tankless water heaters supply you with an endless supply of hot water, since there is no tank to fill. Depending on the model, these tankless water heaters deliver between 200 and 500 gallons of fresh, hot water every hour, when you need it. The Takagi tankless water heaters are ideal for the home, commercial space or anywhere that you require a source of hot water.

The TK4 model is for light residential use and can be used for special projects. It weighs just 40 pounds and is only 13.8 inches wide, so the ultra-compact design lets you mount it on a wall. This unit begins heating water at 1/2 gallon per minute and keeps the endless supply of hot water running to a maximum flow rate of 7 gallons per minute.

The T-KJr2 is the smallest unit offered by Takagi in the tankless water heaters. It is perfect for the small apartment and radiant heating applications. The T-KJr2 can meet all of the hot water needs for a small home or an apartment that has one or two bathrooms as well as for a small office space. It can be wall mounted and it has an efficiency rating of 81% using natural gas and 83% with natural gas.

For installing outdoors, the T-K4-OS model has a built-in power venting system and it does no require any additional Category III venting or vent caps. This model has a thermal rating of 83% for natural and propane gas so it is extremely efficient and environmentally friendly. It only burns gas when you need hot water, so installing this water heater can help you save up to a whopping 45% off your monthly home gas bill. You are offered four temperature settings that range from 113 to 167 degrees.

The Mobius T-M50 or “The Monster” as it is called, is designed for commercial applications. This unit features a dual-combustion system for added redundancy. In the case of an emergency, if one system fails, the other systems continues to run. You can easily link up to four units together with the T-M50 and you can connect up to 10 units and generate over 14.5 GPM. The T-M50 uses HRS copper-the highest grade copper in the industry, so it is very resistant to erosion and leakage.

The Takagi tankless water heaters are efficient, reliable and the logical way to get hot water to your home, business or commercial space, as you will save both money and space.

Best 5 Point-Of-Use Tankless Water Heaters

Tankless water heaters are valuable when it comes to providing hot water for your home’s use. And that is especially true now that the winter season is fast approaching. Here’s our list of the best 5 point-of-use water heaters.

1. InSinkErator SST-FLTR 2/3-Gallon Stainless Tank and Filtration System

The InSinkErator devices are revolutionary tankless water heaters which deliver hot water for your household applications ’round the clock. They are durable, convenient, and work with minimal supervision. There’s nothing more you can ask for from this home improvement gadget.

Showcasing a whopping capacity, it gives you more water than the previous models. Along with that, they come with guns blazing boasting a patented top mounted expansion chamber as well as special aspiration system. With it, this tank delivers on demand flow of hot water as well as unrivaled performance.

Together with a thermal protection system hand in hand with a stainless steel core, you are guaranteed that this tankless water heater is protected from overheating and will serve you for the years to come without slowing down.

Let’s check out some features that you will LOVE! Some devices come with Filtration System which gives you fresher tasting water Plastic fittings A temperature control that is ABC-easy to adjust Comes with tool-free tank connections as well as dry start protection which make it easier to install Showcases 60 cups/hour of near-boiling water…all ready for your personal use! Backed up with 3-Year Manufacturer Warranty…and this is no ordinary warranty, this is HOME service warranty we are talking about.
-115 volts, 750 watts, 6.25 amps
-NSF and UL listed

2. Bosch GL4S Ariston 4-Gallon Point-of-Use Indoor Electric Mini-Tank Water Heater

This Ariston 4 Gallon Point Of Use Water Heater this unit from Bosch virtually gets rid of the need to wait for your hot water to come from the sink faucet! You see, you can easily install the heater independently or have it attached in line with a much bigger water heating source.

Hard wiring your water heater? Forget about it! There’s no need for that. All you have to do is plug it into any standard outlet and that’s about it. This tankless water heater is good to go. The glass lined tank makes sure it has a long life. Along with that, the superior insulation gives you quick recovery as well as better energy efficiency rating.

This 120-volt and 1500-watt tankless water heater weighs at 17 pounds and comes with the dimensions of 14-by-14 by-12-1/4 inches.
And to make the deal even sweeter, the manufacturers Ariston, backs it up with a 6 year limited warranty for your heat exchanger and 1 year limited warranty for the parts of the unit.

3. Rinnai R94LSi Natural Gas or Propane Indoor Tankless Water Heater, 9.4 GPM

Made for indoor installation use, the Rinnai R94LSi-N Natural Gas (or Propan Rinnai R94LSi-P) Indoor Tankless Water Heater allows you to enjoy non-stop and flowing hot water for up to 5 plumbing as well as appliance outlets all at the same time. Not to mention it’s always at a consistent and pre-set temperature.

Coming with a capacity of up to 9.4 gallons of hot water for every single minute (GPM), you are guaranteed that this water heater can still give you up to 40 percent energy savings…as well as savings in space too as this unit is very compact.

Compact and powerful, this Rinnai interior-mount unit vents straight to the outside with a concentric venting system. If you are living in a mobile home, no problem! This comes with certification for installation in manufactured and mobile households Showcases a commercial-grade heat exchanger which is good both for home and commercial applications Comes with its guns blazing…boasting a MC-91-1US Digital Controller with Error Code Indicator This unit comes pre set at 120 Fahrenheit Safe! It meets the strict California and Texas NOx Emissions Standards
What more could you ask for?!

4. Rinnai R75LSi Indoor Tankless Water Heater, 7.5 GPM

Built from the ground up for indoor installations, with the Rinnai R75LSi, you no longer have to plan your mornings and evenings around your water heater. All you have to do is set your own schedule and that it it’s all up to the R75LSi to get the job done.

This tankless water heater is ideal for 2 to 3 bathroom homes. It’s more than enough to deliver 7.5 gallons of hot premium water (GPM). And here’s the better part, it saves you energy and money in the process!

To get started, you just have to mount this water heating unit in practically any room! After that, vent it outside with a single wall or through roof penetration. Get that done and you are well on your way to getting hot water consistently.

Other Niceties You Will LOVE! So you’re living in a mobile home? That’s NOT a problem! This has certification for installation in manufactured and mobile households Comes with a commercial-class heat exchanger. Whether for home and commercial applications, this is more than good enough! You will definitely love the MC-91-1US Digital Controller with Error Code Indicator that the package includes. This water heating unit comes pre set at 120 Fahrenheit You are guaranteed that this is safe. You see, it meets the strict California and Texas NOx Emissions Standards

5. Eccotemp Systems Portable Tankless Water Heater with Shower Head

So you need endless hot water delivered to a bathroom or sink without skipping a beat? Yeah? NO PROBLEM! This Eccotemp point-of-use tankless water heater is here to get the job done for you. You get hot water EXACTLY where you need and EXACTLY when you need it. This makes this water heating unit perfect for camping, cabin use, washing your boats and cars, and those are just to name a few.

Just switch this heater on and intense flame heats the water that passes through it RIGHT AWAY! Yes, this heater doesn’t fumble around no reservoir to deplete. As long as you feed water in, you are guaranteed to have hot water coming out.

And here’s the good part, it only starts flame when there is water running through it. That means you don’t run the risk of overheating this point-of-use unit. Gives 1 gallon of hot water per minute CONSISTENTLY! Easily adjustable water temperature control 80 to 150 degrees F The adapter easily attaches to your regular garden hose style nozzle The package comes with a hose as well as a regulator which makes attaching to an LP tank a piece of cake

Green Hot Water: Installing on Demand Water Heaters

While many of today’s modern water heaters can be as energy-efficient as or more energy-efficient than a tankless model, many older models are essentially outdated compared to today’s modern on demand water heaters. Typically wasting about 20 percent of the energy they consume through heat loss-AKA standby loss, an outdated water heater can easily be replaced with a tankless model or on demand water heater.
In older water heaters, the water is heated up as it fills the tank. Heat loss occurs through the sides of the tank and is lost. The water needs to be constantly reheated-especially in colder climates-and accounts for 20 percent of the energy they consume.

An instant, on demand or tankless water heater will consume no electricity or gas until they are needed. As cold water flows into the on demand water heater, a check valve alerts the heating device that water needs to be heated. Water can be heated to 120 degrees or more in as little as a second or two. This provides the ultimate in green water heating technology.

The real amount of energy savings is dictated by the amount of hot water your home and families use. For instance a smaller household of two or less people use roughly 40 gallons of hot water daily with a conventional water storage heater. This can be reduced to half the water use and a 25%+ in energy savings daily.

A larger household uses more water-let’s say double the amount. AT an 80 gallon a day rate, savings calculate to about 10%+- each day. Why such a big difference? Because a constantly used water heater has less standby loss due to the constant recycling of water through the heater.

Know your peak use and GPM rate before you buy any water heater. This can help gauge what model water heater is best for you and your family. Check out Consumer Reports Website to calculate your homes GPM and get more information on choosing the greenest water heater available.

Tankless Water Heaters

The first experience I had with a tankless water heater was in Singapore, many, many years ago. There were three: One for each bedroom and one for the kitchen. Many things seemed strange to me since it was my first time out of the states, but these tankless water heaters were some of the strangest. They were not new by any means but they immediately supplied as much hot water as we needed whenever we needed it. They were not as small as the units made now, but they were a lot smaller than the hot water tanks we’d been used to.
Now, you can find tankless water heaters that are made powerful enough to heat an entire house instead of just one bathroom or the kitchen, so you only need one. The sizes run from small enough to install under the sink in an RV or large enough to heat water for a commercial operation. They’ve come a long way!

The only difference you’ll notice (besides having an endless supply of hot water) is that you will have to turn the water up to a certain flow before the heater will come on. If the heater is adjusted well and the filter is clean, you will hardly notice. With our three units, we had to turn the water up quite a bit before the heater would turn on. The technology for both gas and electric tankless heaters has progressed tremendously since those days in Singapore.

Tankless water heaters cost more to purchase than traditional tank heaters, but they will save money over time and are a good investment with utility prices going up and up everywhere. If you’re interested in buying one, be sure to look for the Energy Star label to save even more gas or electricity over the life of the heater, which, by the way, is much longer than a tank heater – twenty years, easily. That’s twice the life expectancy of a traditional tank heater. When you figure the length of use and the savings on gas or electricity, a tank heater can be quite a bit cheaper to operate and much more convenient. No more cold showers or waiting for the water to heat up again.

Another great advantage is the space saved. Tankless water heaters by definition take up less room than a tank and since they’re installed on the wall, they free up what little floor space they would take. That makes them an excellent choice for apartments, recreational vehicles and anywhere else space is needed.

Both electric and gas tankless water heaters are practically maintenance free other than cleaning a small filter occasionally. There is a downside to this though. You must be sure that the plumber chosen to install the tankless heater is familiar with them and knows how and where to put the filter as well as other minor differences.

A tankless water heater can replace all conventional heaters and work with solar and other alternative types to ensure that you always have enough hot water for anything you do.