For any household considering investing in a tankless gas water heater, or for those who wonder what it is all about, it is important to understand what it is, the pros and cons of having one and which ones on the market are the best to go for. Let\u2019s start with what these are \u2013 in essence, it is a water heater that uses gas to heat water but doesn\u2019t have a storage tank for the water. It will heat the water when you run the tap or turn the water on, taking away the problem of having to wait for the water tank to fill before having access to hot water. Perhaps the biggest benefit of choosing a tankless water heater is its energy efficiency when compared to other products. You\u2019re not going to have a system constantly heating and re-heating a tank of water, even when you don\u2019t need it, instantly reducing costs to your energy bills and helping reduce the environmental impact. Our Top Picks Best Gas Tankless Heaters of 2020 Gas Tankless Heaters that are worth mentioning: Our Top 10 Gas Tankless Heaters We\u2019ve spent time reviewing the latest and best gas tankless water heaters on the market and put together ten of our favourites, to help you understand what is out there and guide you to the best one for your property. Should you prefer natural gas or propane for your water heating needs, we've got you covered. 1. Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater The first on our list is this tankless water heater from Rinnai, a sleek, stylish designed product which has been given a metallic design to make it fit with many modern properties. Size: The designers have not only thought about looks but function as well, with it being designed to save space and fit in far smaller areas when compared to some of the alternatives. Efficiency: In terms of energy efficiency, this is a concentric model with the possibility of PVC venting should you require it, all leading to one of the best efficiency levels of up to 0.96 Energy Factor, as well as claiming to have ultra-low NOx emissions. Installation: The only real downside to this product is the concentric exhaust requiring some additional parts and so this adds to the cost. Pros Cons \tVery low NOx emissions \tCompact design \tThermal efficiency rating of 95% \tIt\u2019s concentric exhaust requires additional parts 2. Rheem RTGH-95DVLN Indoor Direct Vent Tankless Natural Gas Water Heater Let\u2019s start with the most important feedback \u2013 the energy efficiency and we are really impressed with this water heater. It certainly makes it one of the best tankless water heaters on the market. Efficiency: The efficiency is a fantastic 95% on this model and that is why it\u2019s one of our favourites. It has been built with efficiency in mind, with its heat exchanger being made out of stainless steel to add to the energy efficiency. Features: It also has some other interesting features that we feel make this tankless heater from Rheem stand out. Firstly, it has electronic controls which are easy to use and effective, helping with safety and energy efficiency. On top of that, it has been built to utilise a PVC two-pipe direct vent system and the manufacturers state it has freeze protection and low NOx emission. Limitations: That is all sounding great so far but we do need to inform everyone that our tankless water heater reviews have shown it to be a bit on the noisy side and the maximum temperature isn\u2019t as high as some of the other models, though still good enough for most households at 120. Pros Cons \tIt features a helpful digital display \tIt has a two-pipe direct vent system \tIt has an energy efficiency rating of 94% \tIt features freeze protection \tThis model is one of the noisier options \tThe maximum temperature is 120 3. Rinnai RUC98iP Ultra Series Propane Tankless Water Heater We head back to Rinnai as we continue our best tankless water heater list and the primary difference here is that it uses propane, as opposed to natural gas. Design: It has been designed with the same metallic finish as the previous model so it will fit in nicely with most properties. Furthermore, it comes with a similar energy factor of up to 0.96 and as a result of the technology within, offers barely any NOx emissions, great news for all households. Maintenance:: This system offers both options for venting \u2013 PVC and concentric, as well as a generous manufacturers warranty ranging from 1 year for labour, up to 12 years on the heat exchanger. Performance: This long-lasting product will repay your initial investment but we have found customers report that it can take up to one minute for hot water to appear, after turning on the tap, which could be frustrating for many. Pros Cons \tIt has a 9.8 GPM flow rate \tIt has an energy efficiency rating os 96% \tThis system emits very low NOx emissions \tFlow rate for hot water can be slow, with some reports of up to one minute for hot water to reach faucets. 4. Eccotemp i12-NG Tankless Water Heater This gas hot water heater from Eccotemp truly is one of our favourites, particularly in terms of design and effortless makes it onto our best tankless gas heater reviews. Design: It has a modern, sleek design combining silver with a black glass front which incorporates a fantastic LED display and control system. Of all the products on the market, we think this one fits into almost any modern kitchen the best. Efficiency: The modern approach to design is mirrored in its energy efficiency and energy savings, starting up when required, so it is not constantly running and costing you money. Features: Throw in some child-lock technology and automatic temperature controls and you\u2019ve got a great water heater. Installation Sadly, the exhaust on this model can get quite hot, so you need to think about the correct installation and protection but whilst we are on the subject, it isn\u2019t the easiest to install anyway, so you may want to get help with it from a professional. Pros Cons \tA helpful LED display and control system \tA reasonable water flow rate of 3GPM \tIt is an energy efficiency system \tInstallation can be difficult and may require additional support. 5. Gasland BE158 1.58GPM 6L Outdoor Portable Gas Water Heater The next product we recommend for you is a little different from the rest and that is because it is a portable water heater. Despite being portable, it is still one of the best tankless gas water systems around. Safety: Due to the fact it\u2019s an outdoor portable device, the guys at Gasland have thrown in a whole host of safety features that give you true peace of mind, including antifreeze, overheating protection and automatic controls on the water pressure. Features: They have thought about what people want from a portable device and this meets the criteria, being a nice compact design and relatively lightweight, so transporting and mounting the heater isn\u2019t a problem, particularly with handy mounting brackets. It doesn\u2019t let you down on the energy efficiency front either, carefully designed to minimise fas consumption. Instructions: One downside we did find was that the supporting instructions are somewhat lacking, so you may need to go with some trial and error before getting the right shower. Pros Cons \tImpressive safety features to protect you and your home \tA water flow rate of 1.58GPM is enough to provide hot water for an RV or single point of use \tIt has been designed to be compact and lightweight, particularly when compared to a tank water heater \tInstructions provided don\u2019t cover all features of the system, such as the dials on the front of the unit. 6. Bosch Greentherm C 1050 ES Propane Tankless Water Heater We turn to an electronics powerhouse in Bosch, who has delivered another propane gas tankless water heater. Features: Firstly, you will notice this comes with a mobile app to help with controlling the unit and monitoring it. A high-tech feature that is a nice extra but we aren't sure how useful yet. Alongside that, you will get a bypass line to keep the hot water and cold water separate from each other. Performance: Depending on the temperature, you will get an impressive water flow rate ranging from 6.8 gallons per minute (GPM) for temperature rises of over 50 degrees and 10.7 GPM for lower temperature increases. One of the stand out gas-powered performers on our list and compares well to these and electric tankless water heaters. Efficiency: Not content with just having an impressive flow rate no matter the temperature outside, Bosch claim this tankless water heater has a 96% thermal efficiency and 0.95 energy factor. Fantastic news for your energy bills! Pros Cons \tImpressive water flow rates of between 6.8GPM and 10.7GPM \tHighly energy efficient thanks to a thermal efficiency of 96% \tItUseful technology include a bypass for keeping water lines separate and a mobile app for controls \tThe only real downside we can find is the aluminium heat exchanger. \tOther materials would have offered a better performance 7. Takagi T-KJr2-IN-NG Natural Gas Tankless Water Heater Another of our budget-friendly gas tankless water heaters now and you will certainly get plenty of hot water. Performance: Despite its price, you will get a more than a reasonable flow rate of 6.6 gallons of water per minute (GPM) with the Takagi T-KJR2, performing well enough for the whole house when multiple faucets on at the same time. It also has monitors built-in to keep an eye on temperature fluctuations when demands are high. Maintenance: It comes with a good 10-year warranty on the heat exchanger, so you know it's built to last a long time and at this price, marks a very good investment for your household. Ventilation: The guidelines are pretty strict with this Takagi tankless water heater and you must use a 4" stainless-steel ventilation system. Not the end of the world but it may frustrate some customers. Pros Cons \tA good flow rate for a cheaper unit at 6.6GPM \tA well-designed unit that is compact and relatively light \tTemperature fluctuations are minimal thanks to its internal monitors \tThe ventilation can be expensive and may add to the overall cost \t 8. Rinnai RUC80iP Ultra Series Propane Tankless Water Heater A strong performer is next on our list of the best gas tankless water heaters and it is a new model from Rinnai, another well-known manufacturer. Features: It comes with a raft of useful features to make life easier for you and your family and that starts off with being wifi-ready. This means you can control it from your smartphone or tablet, as well as getting maintenance notifications. Flow rate: Back to the more conventional aspects of gas-powered tankless water heaters and its flow rate is a strong 8.0GPM. Despite this, it still manages to keep NOx emissions low so you don't have to be concerned about the impact on the environment compared to some of the other models. Efficiency: Just like many of the hot water systems on here, it has a high energy efficiency rating of 96%. Pros Cons \tIt has ultra-low NOx emissions to reduce your carbon footprint \tImpressive range of wifi features \tA great flow rate of 8GPM \tThis tankless water heater must be installed outside \t 9. Rinnai V75iN Natural Gas Indoor Tankless Water Heater Another from Rinnai to make it onto our best tankless water heaters (gas) now and it is this Natural Gas version. Flow Rate: The manufacturer states you will get up to 7.5 gallons per minute (GPM) for this hot water heater, which is pretty reasonable and should be more than enough for the average-sized household. Efficiency: Despite the fact you can run multiple showers and faucets with this model, it is still a highly energy-efficient unit with an energy factor of 0.82. This does depend on certain things like the incoming water temperature but it is still one of the most efficient for the price. Features: It has settings that range from 98 to 140 degrees Fahrenheit, a temperature lock to secure the settings and a smart safety system. You even get a leak detection system within which is a massive plus for those who worry about the safety of gas water heaters. Pros Cons \tAn impressive range of features including a leak detection system for maximum safety \tA highly energy efficient unit with an energy factor of 0.82 \tA flow rate of 7.5 gallons per minute (GPM) \tThere is a delay from when you turn the water on at the faucet to getting hot water. \tSomewhere in the region of 30 seconds which may frustrate some people \t 10. Rheem RTGH-84XLN We've decided to finish our list of the best gas tankless water heaters with this Rheem RTGH-84XLN tankless water heater. Performance: Perfect for larger households and bigger families, this gas-powered system has a flow rate of 8 gallons per minute (GPM) and will offer hot water at a mere 0.4GPM, meaning no matter the demand it will provide hot water to the whole house. Aside from that, it allows you to control the flow of water to the unit, potentially saving thousands of gallons of water per annum. Installation: As we'd expect from Rheem unit this is fairly easy to install and comes with fantastic instructions and support so you won't need to worry too much. Maintenance: One of our favourite benefits from buying this unit, despite it being on the larger side, is its maintenance support. A clear, informative LCD screen will provide warnings and notifications and you get a remote control to help operate and check the various systems. Pros Cons \tIt comes with a remote control and internal features such as built-in blower \tA good flow rate of 8.0GPM \tEasy to install and good maintenance support features including an LCD screen \tIt is a big unit so you need to make sure you have the space for this hot water system \t Summary We hope this article has provided you with a strong overview of what a tankless gas water heater is and how they can be a fantastic addition to your household or even camper van for those travelling the country. As always with any water heater, filter or another kind of system, make sure you consider the usage, quality of water and infrastructure in place, before making a purchase. Once you\u2019ve done that, then check out our favourites and see whether they are the right fit for your property. Types of Tankless Gas Water Heaters Now that we\u2019ve briefly touched on what a tankless gas water heater is, we want to tell you about the three main types on the market and the differences between them, to help you make an informed decision. Condensing This type of tankless heater utilises a second heat exchanger that comes into play after the primary one, reuses the heat generated from the exhaust to heat more water. As a result, this increases the efficiency of the product, up to a potential 94%, as well as offering safer ventilation options. However, this model can cost more than other types so it is a delicate balance between cost and improvements in efficiency levels. One final consideration here is that it isn\u2019t the most efficient solution for short water draws and by this, we mean short bursts of water for washing your hands. So again, think about your water usage and whether this is important. Non-condensing The non-condensing heaters use a single heat exchanger to heat water when you run a tap or request it to do so, a technology that has long been used in Europe and parts of Asia. As such, they are known to be very reliable sources of water heating, with minimal issues and an efficiency of up to 85%. The main problem with this type of tankless gas water heater is that you will likely need to install additional vents due to the temperature levels of the exhaust, losing energy efficiency. Hybrid The hybrid condensing units are a newer system and so lack the availability of the other models, but they do have some very interesting advantages. Firstly, this unit utilises a small water container, using it as a reservoir of hot water and as a result, increasing energy efficiency, even when using them for short draws, such as washing your hands. They don\u2019t need as extensive ventilation as non-condensing, reducing the cost to purchase and install.The hybrid condensing units are a newer system and so lack the availability of the other models, but they do have some very interesting advantages. Firstly, this unit utilises a small water container, using it as a reservoir of hot water and as a result, increasing energy efficiency, even when using them for short draws, such as washing your hands. They don\u2019t need as extensive ventilation as non-condensing, reducing the cost to purchase and install. Due to the relatively small group of companies producing these, you may find your choice limited and even then, you will generally have to go to a less well-known company, so make sure you check their build quality and warranty support. The Pros and Cons No matter what problem you\u2019re trying to resolve, the different solutions open to you will have both pros and cons. Gas tankless water heaters are no different and it is important to understand all of the implications before making a purchase. Pros There are plenty of pros to choosing these tankless water heaters for your property, whether that is a house, office or mobile home and we\u2019ve listed a few of them below for you: Instant hot water The purpose of tankless water heaters is that they offer hot water without waiting for a water tank to fill up or refill if you\u2019re using a lot of water. So you can say hello to on-demand hot water whenever you need it. Energy-efficient systems No matter which type of tankless heater you go for, they offer great energy savings and depending on the design, they offer energy-efficient units up to 96% efficiency, leading to great saving on your gas bills. Long-lasting It is our expectation that well maintained tankless units can potentially last up to 20 years, compared to roughly half that for tank units. So, despite the higher initial costs, these really do win in the long run. Reduced costs You will no longer have a water tank being heated up repeatedly to ensure there is hot water on standby, reducing the costs of your energy bills. Not only that, but they also offer a reduced impact on the environment, savings for you and the world. Size The tankless gas water heaters are far small than the tank equivalent because you are obviously ditching the water tank part. This means they are suitable for smaller homes, alternative properties and far easier to implement into your home water systems. Cons Despite the clear benefits of purchasing a tankless gas water heater, there are some cons that people should be aware of, as they may alter your plans: Initial cost The biggest setback to choosing this type of water heater is the initial cost of buying one. When we compare it with traditional heating options, you are looking at potentially double the price, if not more. Consider also the potential need for professional installation services and retrofitting and you can see the prices rise. Home modifications If your home is not set up for a tankless gas water heater, then you will potentially need to modify the gas systems, as well as making sure you have the appropriate ventilation. The vast majority will require work completed by a professional and some extra equipment fitted. Temperature fluctuations As a result of not having a tank of water pre-heated, customers who buy these products may notice fluctuations in the water temperature, particularly if you have multiple taps running at the same time or are in a high-usage property. However, you will come across different issues with water tanks for high-usage properties, so either way, you will see some issues. More equipment It is important to think about the type of water supply you have in your household and should it be hard water, then you will need to consider adding a softener into the system, which will add to your initial cost and affect the space needed for the entire system. Make sure you\u2019ve budgeted for this and it all fits. Key Considerations There are some important considerations to be aware of and incorporate into your buying decision and we have put the most important ones together into a helpful list on this gas tankless water heater list. Flow Rate One of the most important considerations for any type of tankless water heaters, whether that is a gas one or an electric tankless water heater. This will determine whether the hot water system can cope with the supply of hot water that your household needs and how frustrated you get by a lack of hot water or delay in the hot water arriving. The majority will come with a more than reasonable flow rate but you should do some reading on the flow rates required for different house sizes. A single faucet would cope with 1 gallon per minute (GPM) heaters but clearly, that won't suffice most normal households hot water needs. Energy Factor The energy factor is what you need to look at to understand how much it will cost to use gas tankless water heaters. It is used to calculate the hot water systems energy efficiency and will often be written in 0.xx (e.g. 0.85). It is calculated by the fuel cost you pay being multiplied by 41045 and then 365. Once you have this number, you divide it by the units energy factor and then multiple it by 100,000. This is quite confusing but there are helpful tools online too! The majority of the best tankless water heater systems on here will have a good energy factor or energy star. Budget Not a fun consideration but an important one. You will likely have an idea of budget but it is important to think about what heaters that budget will get. If you do a quick check of the hot water systems in your price range, you will have an idea of the performance levels. If they don't offer what you need, then you may want to re-think your budget or go for an alternative solution. Obviously, the best gas tankless water systems will demand higher prices. Equally, keep in mind that you don't necessarily have to spend a fortune to get one that will suit your households hot water needs. Take your time to think about what exactly you need. Ventilation As a result of you choosing to go for one of these gas tankless water heaters instead of an electric hot water heater, you need to think about ventilation. A ventilation system will remove any harmful gases generated by the hot water heater and is particularly important if the unit is inside your property. You will traditionally have two options when buying one of these tankless water heaters. Firstly, you can go for power venting which using an exhaust pipe. Alternatively, you can go for direct venting which requires both an exhaust pipe and intake pipe. The main difference is that direct venting has an intake pipe to ensure there is enough air intake for the system. Brand Some of us prefer to go for the safety and security of a well-known brand. For gas-powered tankless water heaters, there are some manufacturers that appear on many best hot water heater lists and these include Rheem, Rinnai and Bosch. You can't go too far wrong with any of these and they have the benefits of a fantastic reputation, long-term support and safety records. If you search our tankless water heater reviews you will spot these manufacturers time and again. That doesn't mean you can't go for another brand, just make sure they have all the relevant safety certification and look at customer reviews for added peace of mind. Frequently Asked Questions Will one gas tankless water heater deliver enough hot water for my household? \t\t \t\t\tThe short answer is yes but it does depend on the model you go for and its performance. Gas tankless water heaters are efficient, powerful units so as long as you select one that meets your requirements, you will be fine. \t\t \t \tWhat if I live at a high altitude? \t\t \t\t\tThis does have an impact of gas tankless water heaters, unfortunately, as they lose efficiency as the altitude increases. It is good to do some research on this before choosing to buy, or it may be worth going for an electric model. \t\t \t \tAre gas tankless water heaters better than electric ones? \t\t \t\t\tBoth models have very different benefits and so it isn't as simple as yes or no. You should make a comparison between the two by checking customer reviews and guidance information on our websites first. \t\t \t\t\tCertainly, gas is normally more powerful units and gas energy prices are often cheaper from your supplier, so this sways many people into buying a gas tankless water heater. However, electric has its benefits such as being smaller and often cheaper.