The Tempra 24 is a top tankless water heater and one of the most technologically advanced on the market right now. It is an electrically operated unit with an incredibly sleek and compact design and cutting edge digital temperature controls, though what really sets this product apart from others is the Steibel Eltron Advanced Flow Control System. 

During periods of low and medium hot water demand most models will cope given that they are of a high enough capacity. However having said that though this is not always the case. Some are simply not capable of delivering a continuous flow of hot water from multiple sources when required. The Advanced Flow Control System identifies periods of high demand and automatically adjusts the flow rate to ensure you can have continuous hot water from every outlet in your home simultaneously.

The Tempra 24 can operate on a 208 or 240 volt input and requires 2x 60 amp breakers on 6/3 and 6/2 gauge cables as it can at times pull as much as 115amps. Flow rates are excellent - 3GPM (Gallons Per Minute) at 55 degrees F, 5GPM at 33 degrees F and 8GPM at 20 degrees F, also the plumbing fitting sizes are 3/4" which accommodate for a much faster flow rate than that of 1/2" fittings.

The standout feature of this water heater however is the money it will save you, many buyers claim to have slashed as much as 20-30% a month off of their utility bills. It is very reasonably priced and in line with competitors which is great, especially when you take into account that this is a superior product, depending on how much you save you could even recoup your investment on the Tempra 24 within 12 months. 

It comes with a 3 year warranty, which while still respectable is not as long as other brands offer so this is something to consider, also the warranty is only valid if you have your unit installed by licensed personnel which is typical of most manufacturers.

Overall this is one of the most impressive units that money can buy right now, the Tempra 24 is extremely reliable and proven, as are all of Stiebel Eltron's products and this is what makes them such an impressive brand. They are a very well respected company with countless positive reviews of their products, in fact there are few companies that can boast the excellent consumer ratings they do, which really is a testament to their transparency with customers and the fact that they are synonymous with producing first class products. The Tempra 24 Plus is Tankless Heater Guide's highest recommendation.

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Best For:

• Familes of 4-5 or more with high demand

Specifications:

• 240 Volts
• 24 KW
• 99% Energy Efficiency
• Digital Interface
• 92 Degrees F Temperature Increase
• Weight: 15.4 lbs
• Dims: 16 5/8 x 14 1/2 x 4 5/8 
• 3 Year Warranty

Advantages:

Japanese manufacturer Takagi are a leading brand and are well known for producing highly reliable and long lasting units with a number of consumers citing them as "rock-solid" and working faultlessly for families of even 5 or 6 people. In fact this combined with its very reasonable price makes the Takagi T-KJR2 our value for money recommendation, with many consumers saying it is a market leader.

The unit is gas fired with inputs of 140,000 BTU and boasts a flow rate of 6.6GPM at 35 degrees F and 3.3GPM at 70 degrees F, these are very respectable output capacities with Takagi themselves claiming it can support up to 2 bathrooms in warmer climates and even underfloor heating systems. Required fittings are 3/4", although 1/2" are available for similar models in the range which you may want to look into should these be necessary for you in particular.

The T-KJR2 also sports some very impressive safety features such as an automatic shut off and transfer in to a safe mode should temperatures rise to potentially dangerous levels. It also has preventative measures to protect against frost and water surges.

One thing we must note with this unit though is the fact that it is an indoor, natural gas fired unit, meaning it requires ventilation to the exterior of your home. This can be a concern for some potential buyers who may think this sounds costly and/or complicated however in reality it actually is not. The T-KJR2 can support both horizontal or vertical ventilation and Takagi carry an abundance of parts to ensure customers can configure their ventilation system to the requirements of their particular home.

The only real downside with this product we can see is that consumer reports on the difficulty of installation vary considerably with some claiming it was a simple process to others who were completely unable to install it themselves and everything in between. In the interest of safety and also as is the case with other water heaters, the warranty on the T-KJR2 is only valid should you have this installed by a professional so we do recommend this as the course of action you should take.

Overall this is a top tankless water heater and one of the best that money can buy right now. Takagi's reputation for manufacturing extremely reliable long-life units combined with the excellent pricing makes the T-KJR2 Tankless Heater Guide's value for money recommendation. If you are on the lookout for a powerful and reliable unit then this unit should be a serious consideration.

Best For:

• Large families with preference towards a gas operated system
• Outdoor natural gas model available
• Indoor and outdoor propane powered units of this model also available

Specifications:

• BTU: 140,000
• Max Flow Rate: 6.6GPM
• Constant temperature monitoring via inlet/outlet thermostats
• Weight: 37 pounds
• Dims: 6.7 x 13.8 x 20.3
• 10 year warranty on heat exchanger
• 5 year warranty on parts

Advantages:

This unit is wall mounted and is a very good choice for those of you who have larger families as it boasts a maximum flow rate of 6GPM, meaning it can support 4 showers simultaneously with no detrimental effect to hot water output whatsoever.

One of the most impressive features we found with this unit is it's digital temperature control, it is so powerful that it allows you to set water temperature by as little as 1 degree between 80 to 140 degrees F, this means you can be ultra vigilant with hot water and energy output to ensure a maximum saving on your monthly bills. EcoSmart claim the unit can save you as much as 50% per month, we did not independently verify this ourselves however considering the accuracy of the digital controls it is more than likely true.

The unit has an output of 27KW at 240 volts and fittings are 3/4" to support the large flow rates, yet it has a very sleek and compact, space-saving design. It is electrically operated which means it is typically much easier to install than a traditional gas tankless water heater. Also many consumers we spoke to were able to install it themselves although we recommend having a licensed professional do this for you, especially as the Eco 27 comes with an excellent life-time warranty so you want to ensure you qualify for this.

All in all the Eco 27 is an excellent unit and is our best energy saving recommendation. In fact if you are in search of the best electric tankless water heater then this is a strong contender. It's digital temperature control accuracy, money saving potential, life-time warranty and low price make it the best rated tankless water heater as it mixes high functionality with affordability. A real consumer favourite.

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Best For:

• Medium to large residences with high hot water demand

Specifications:

• 240V
• 27KW
• Dims: 17 x 17 x 3.75
• Weight: 13.75 pounds
• Copper Exchanger
• Digital temperature interface
• 99.8% energy efficiency rating
• Lifetime warranty (if installed by licensed professional)

Advantages:

Rinnai are the largest gas product manufacturer in the world and are well known for their high engineering standards. Rinnai units are among the few who are certified Energy Star holders, meaning they are recognised by government backed organisations for excellence in energy efficiency and safety.

If you require an ultra high demand unit then you should definitely consider this Rinnai tankless water heater, in terms of flow rate it is by a considerable margin the most powerful product on our list. It is a gas operated water heater and carries 3/4" fittings which is no surprise considering the sizeable flow rate.

Prior to our research and Rinnai RUC98IN review we were quite concerned that it would be extremely noisy due to how powerful it is, however as it turns out it is almost completely silent, even quieter than other smaller units with lower outputs, there are also countless consumer reports and reviews citing the same pleasantly surprising finding.

BTU output maxes out at 199,000 and temperature ranges can reach as high as 140 degrees F and 160 degrees F for household and commercial installations respectively. Due to the power of the unit it can support countless showers and sinks making it ideal for ultra high demand properties. Like any gas or propane tankless water heater however it does require ventilation which can be either horizontal or vertical. 

Warranty periods are very respectable. For residential installs there is a 12 year warranty on the heat exchanger, 5 years on parts and 1 year for labor while for commercial installations the heat exchanger carries a 5 year warranty, 5 years for parts and 1 year for labor. Like other products on the list you must have your unit installed by a professional to qualify for warranty.

One thing that must be noted regarding the RUC98IN is that some consumers have reported it sometimes does not fire unless there is high demand. However it seems that this is only when the temperature control is set to higher ranges (140 degrees F) and the problem can be solved easily by dropping the temperature to around the 125 degrees F region.

Overall if you require an ultra high demand model capable of supporting a number of bathrooms simultaneously then you should seriously consider the RUC98IN.

Best For:

• Large, high demand residences

Specifications:

• Max BTU: 199,000
• Space saving design
• 120 Volts
• Weight: 82 pounds
• Dims: 10 x 18.5 x 26
• Flow Rate: 9.8GPM
• 12 year warrant on heat exchanger
• 5 year warranty on parts
• 1 year warranty on labor

Advantages:

The last unit on our list is one that is quite unique and has turned out to be a massive best seller at many outlets including Amazon. The Ecotemp L5 is compact, portable and cheap and can be used in your home, however with it weighing just 13 pounds it is ideal for camping, trailers, RV's and any situation where "off-the-grid" hot water is a requirement. 

It is the number 1 best selling portable water heater available right now and even comes with a shower attachment. It is powered by 2x D Cell batteries with an optimum operational pressure range of around 20-80 psi, it is also worth noting that many consumers used the unit in conjunction with a 12 volt pump.

All attachments and parts are included with the Ecotemp L5 so set up is very straightforward and many consumers confirm this. The units automatic ignition means burners should activate immediately upon water flow and all that is required for operation is to connect the unit to a standard garden hose nozzle and to hook it up to a propane tank.

Flow rate ranges from 0.5 to 1.4GPM, while this is obviously low in comparison to the other water heaters on this list one has to bare in mind that this is a small, lightweight portable unit so with all things considered this is actually quite respectable. As previously mentioned the Ecotemp L5 is battery operated so can be used anywhere regardless of whether you have access to electricity or not.

Temperature ranges from 80-150 degrees F and it has a minimum operational pressure of 20psi and a maximum of 100psi. One of the things we liked most about this unit is that after 20 minutes it automatically shuts off, a great reassurance for safety and water saving reasons. The Ecotemp L5 is supported by a 1 year warranty.

Overall this is a very impressive little portable unit, the reviews of this product speak for themselves with some consumers having purchased more than one of these. The multi-functioning nature of this model combined with it's very reasonable price mean it really is an exceptional product and an excellent portable option.

Best For:

• Small residences with only 1 or 2 people or for portable requirements

Specifications:

• Flow rate: 5L per minute
• Weight: 13.23 pounds
• Dims: 14.5 x 11.5 x 4.5
• BTU: 37,500
• 20 minute automatic safety reset
• 3 Volts
• 11 KW

Advantages:

WHAT IS A TANKLESS WATER HEATER?

They work in much the same way traditional tank heaters do in private residences and commercial and public properties around the world. They act to heat water on demand and are usually operated using either gas/propane or electricity.

They are installed between the water source and the demand application with a pipe running through the tankless heaters internal system. So for example when you turn on your hot water tap it will draw (demand) water from the source. This water will then travel through the internal pipework via your tankless system, in turn heating the water before arriving at the application i.e the tap you just switched on.

WHAT ARE THE DIFFERENT TYPES OF TANKLESS WATER HEATER AVAILABLE?

As mentioned above the 2 main types are gas/propane operated units and electric units. The differences are fairly self explanatory with the former utilising gas or propane to heat the incoming water supply and the latter using electricity. 

Gas models are usually the best option for those in need of a product that can support high demand due to their power and very large flow rates and capacities. Also the fact that gas is often cheaper than electricity makes them more efficient if being used very often. One thing that must be kept in mind with a gas heater is that they require ventilation access to the exterior of your building.

An electric unit may be a better option if you live alone or in a smaller residence. This is due to their conveniently compact designs and the fact that electric models require a lot of energy when engaged. However one large upside is that they do not need to be ventilated.

HOW TO SELECT THE BEST UNIT FOR YOU 

Selection all comes down to you and/or your families specific requirements and circumstances. There are a number of factors to consider such as your hot water demand, the climate where you live, your budget and many more.

An ideal place to start is to take a look at your hot water demand and the amount of people and applications the tankless heater will need to service. Should you be a large family that can be running multiple applications simultaneously then you should be researching units that can handle such a demand. Vice versa if you live alone in a small residence then you will not need to splash out on an extremely powerful unit.

Another thing to consider is your budget. Many people just look at the cost of the unit however the cost of installation is also important as it will be a noteworthy sum of money. Speak with multiple local contractors and get many quote to ensure you are getting the best deal possible. Add unit and install cost together along with other factors such as gas or electricity prices and this should narrow down your search considerably.

Other factors are things like your water density (hard of soft) and the climate in which you live. Should you live in a very cold area then this means your incoming water temperature will be naturally very cold meaning your unit will have to work that much harder.

Taking all of these factors into consideration, along with our helpful reviews above should put you well on your way to finding the best rated water heater you possibly can for your specific circumstances.