Choosing the right tankless water heater

Choosing the right tankless water heater

Tankless water heaters are proving themselves to be the wave of the future in water heating with benefits such as never ending hot water, reduced utility bills, and longer, more useful lives than conventional storage tank heaters. Choosing the correct tankless water heater for your application does require some research and planning. Our goal here is to help you determine the best strategy for “going tankless” which will take many factors into account.

Proper Sizing

To properly size a tankless water heater you need to determine your maximum momentary water requirement. In other words, you need to think about when you will be demanding the most hot water. Maybe in the morning there could be a shower running and a bathroom faucet. Tankless water heaters will provide continuous hot water, but they can only provide so much at one time. Each product page on our site will provide you with all the information needed to make the right decision.

  1. Flow Rate Performance: The flow rate performance (FRP) of tankless water heaters are rated by measuring the gallons of hot water that can be output per minute while raising the temperature of your ground water by X° F. Typical high volume tankless water heaters have a FRP of up to six gallons per minute at a 60 degree rise. Smaller heaters have an FRP of around three gallons per minute at a 60 degree rise.
  2. What are My Hot Water Requirements? We have built a tool into our site to help you determine how much hot water you need. Select your maximum momentary usage by inputting how many of each plumbing fixture would commonly be running at the same time. Select your state (the calculator knows the average ground water temperature in your state) and hit calculate to learn how many gallons of hot water you need. The calculator assumes that the tankless water heater is set to 120° F to give you this calculation. Compare your hot water requirements with what each tankless water heater can provide. This is how you size your tankless water heater.

Gas or Electric

Gas powered tankless water heaters run off liquid propane or natural gas. Every model is available in either configuration. You must have a gas line running to your point of installation. Electric tankless water heaters most often will be hardwired into your electric system and have specific circuit breaker requirements. You need to consider convenience and your hot water demands when making a decision.

Most customers considering going tankless are replacing a current storage tank water heater; some are incorporating a tankless unit into a new construction. For those replacing a storage tank, you already have an energy source and the plumbing in place to power a tankless water heater whether it ran on gas or electricity. It would be easier overall to replace a gas storage tank with a gas tankless; and an electric for an electric. Do not consider this a “rule”, however; there are circumstances where it would make sense to switch from one to the other. For example, maybe there are no single electric units that will meet your needs; you would need to seriously consider getting a gas powered unit.

For those installing a tankless water heater into a new construction, you have fewer restrictions. Cost and water requirements will be your main considerations. Electric tankless water heaters are generally less expensive but they also have less capacity than their gas powered counterparts. Also think about your locate energy rates for gas and electricity, one might be less expensive.

Heater Placement Strategies

Deciding where to install your tankless water heater is a very important consideration. There are different strategies to consider; each has benefits and shortcomings. The floor plan of your home and your hot water requirements will dictate the best course of action.

  1. Central Installation
    • Installing your tankless water heater centrally is great because your hot water will not have to travel too far to reach any application. However, central installation can sometimes get you in the position where you have to vent your heater vertically. Vertical installations are usually more expensive that horizontal installations because they require more pipe.
  2. Primary Application Installation
    • You may want to consider installing your heater nearest to your application that will require the most hot water. This would probably be your primary bathroom since the shower is quite often the largest consumer of hot water.
  3. Regional Installation
    • Some consumers with large homes and high hot water demands may want to consider purchasing multiple units to run different regions of their home. This strategy will usually allow you to vent each heater horizontally which will save you money.
  4. Combination Strategy
    • Some consumers may want to consider using a whole-house tankless water in conjunction with electric point-of-use tankless water heaters. The theory behind this strategy is that you would use your whole-house heater to supply you shower(s), and possibly appliances depending on your shower and the output of the heater you have selected. Smaller electric point-of-use tankless water heaters would be used to provide your kitchen sink, laundry sink, and possibly appliances depending on your specific configuration. Although this type of configuration would have a higher startup cost than purchasing a whole-house unit by itself, it does have some decided benefits. (1) Other applications will not draw hot water when you are showering. Depending on your shower and the max output of your water heater; if 1-3 other applications were drawing hot water while the shower is running; the shower will cool down and the other applications probably won’t be as hot as desired. (2) You will reduce heat loss from the water traveling long distance through your plumbing since your hot water heaters will be installed near the application.
  5. Outdoor Installation
    • Installing your tankless water heater outdoors can be appealing since you will not have to purchase a vent system. If you live in a warm climate; this definitely is an option you should consider. However, if you live in a cold climate, where the temperature can regularly get below freezing, this probably is not the ideal application. Water inside the heat exchanger can damage the heat exchanger when freezing occurs. Manufacturers will not warranty a product that is damaged by freezing

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