Best Gas Tankless Water Heater – Buying guide
Selecting the right size tankless water heater
Most tankless heaters are available in various sizes and powers, to accommodate different sized homes. Larger heaters have higher BTU capacities and higher flow rates, meaning that they’re able to supply hot water to a great number of appliances at the same time.
To find the right size heater for your home, you need to find your total required gallons per minute (GPM). Check your faucets, showerhead, and appliances for their listed GPM, either by checking labels or looking up their specs online.
We recommend heaters that can handle a minimum of 4 GPM for families with more than two people.
Understanding flow rate
It’s important to remember that nobody runs all of their faucets and appliances simultaneously, so there’s no need to seek out a heater that can handle an astronomical flow rate.
Most homes are able to operate comfortably with a heater that’s capable of providing water for 1-3 simultaneous showers and appliances, depending upon the number of people in the home.
This tends to work out at a daily maximum flow rate of between 4-10 GPM. However, point-of-use heaters designed for a single appliance, such as the Furrion above, can get away with much lower GPMs.
Another thing to remember when deciding upon capacity and flow rate is that the temperature of incoming water has a large effect on heater performance. In colder climates, heaters have to spend more energy bringing water up to temperature, so likely need a higher BTU and GPM rating.
How much should a tankless gas heater cost?
With more internal components and safety features, gas heaters tend to be more expensive than electric units. The average price for a gas heater is around $750, with point-of-use models available for less than $500, and large whole-house heaters going for +$1500.
You should also take into account the price of installing a gas heater, as it’s far more likely that you’ll need professional help than when fitting an electric model.
Most gas tankless units require gas pipes to be upsized, which isn’t a task you should take on without prior experience.
Despite these significant extra costs, many gas heater owners say that their machines were able to pay for themselves within a few years of use. In the majority of areas, the cost of natural gas heater beats electric, meaning that you’ll slowly recoup your upfront investment over time.
Tankless heater efficiency
Gas tankless water heaters are less efficient than electric tankless units, but they far surpass tanked heaters, with average energy factor ratings of 80-90%.
Some gas heaters contain condensing technology, which allows them to capture unused heat from the exhaust system and redeploy it to heating the water. This can boost efficiency above 90%.
The higher the altitude of your area, the more energy your gas heater will lose as it heats your water. As a general rule, heaters in homes over 4000 feet lose 4% of their BTU and another 4% for each additional 1000 feet.
What is a condensing heater?
Condensing gas tankless water heaters are designed to increase heating efficiency to an equal level with electric heaters. All gas heaters have an exhaust system, which emits air and heat that wasn’t used to increase the water temperature. Condensing heaters capture this residual heat and re-use it to heater water.
To do this, condensing heaters contain a second heat exchanger that pre-heats incoming water before it reaches the main heating component. This also means that the main component needs to spend less energy to bring water to temperature.
Non-condensing gas water heaters are also far more efficient than rational models. They’re also lighter, smaller, and less expensive, making them more suitable for some homes.
How to clean a tankless heater
Most heaters are designed with sediment screen filters, which ensure that the heating element isn’t damaged by small pieces of dirt and particulate matter in the water supply. These screens should be removed and cleaned on a regular basis, depending upon the purity of your water.
Dissolved minerals, commonly referred to as water hardness, are the most common contaminant in water heaters and can build up on copper heating elements to the point where heater performance is severely affected.
Because of this, if you live in an area with hard water, it’s important to flush or “de-lime” your heater on an annual or 6-monthly basis. Flushing a heater involves running an acid solution (some people use vinegar or bleach) through the unit to remove the scale.
Installing a whole-house water filter on the mains water line before the water reaches your heater is a great way to increase the performance and lifespan of your new heater. This is especially true if you use well water, or live in an area with very hard water.
Gas tankless water heater vs electric tankless heater
For many people, the choice between a gas and electric heating system will already be made for you, depending upon the way your home is set up.
If you are trying to choose between the two fuel types, whoever, there are some pros and cons worth considering.
Electric heater pros
- Electric tankless units are cheaper to purchase and install than gas models.
- Electric heaters don’t require venting.
- The cost of electricity is less volatile than gas.
Electric heater cons
- Powerful electric heaters require several large circuit breakers, meaning you’ll need to make changes to your home’s wiring and service panel
Gas heater pros
- The cost of natural gas is likely to be lower than electricity in your area, meaning monthly savings.
- Gas tankless heaters are generally more powerful than electric heaters, able to operate in colder climates.
Gas heater cons
- Installation costs for gas tankless water heaters may be double those for electric tankless heaters.
- Fitting the correct ventilation system for your heater can take up more wall space compared to an electric heating unit.
Tankless vs tank heaters
These days, most new homes are fitted with tankless heaters rather than traditional tank models. This is for a few main reasons:
- A typical gas-fired tank wastes 40 to 50 percent of the fuel it burns, whereas tankless heaters can operate at 80-99% efficiency.
- The best tankless water heaters provide hot water in less than 10 seconds.
- Most reputable tankless heater manufacturers make units that last for decades, with some Rinnai owners reporting 30-year lifespans!
- Because they don’t store large amounts of water, tankless heaters won’t flood your basement or harbor dangerous bacteria.