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Tankless Water Heater Buying Guide

Edwin Ruud’s eyeballs would be spinning in his long-dead head if he were to come back to life and witness the evolution of his invention. Ruud is generally credited with inventing the storage type hot water heater unit back around 1889. His creation allowed water to be heated and stored in a metal tank until a demand was placed on it. At the time, and until recent decades, nothing changed much. But today’s tankless water heater makes Ruud’s invention seem hopelessly bulky and inefficient. Let’s take a look at how the tankless water heater has revolutionized the simple act of taking a hot bath.

tankless-water-heater-buying-guide

SEE ALSO:  Water Heater Buying Guide – Tank Type

 

Undeniable Tankless Water Heater Benefits

  • Never Run Out of Hot Water – Probably the biggest disadvantage of traditional tank models is that you’re limited by the amount of hot water the tank will hold. While it may not be a problem if only one or two people live at home, it becomes a common problem for families. Sure you can get a larger tank but the price goes up exponentially once you go past the standard 50-60 gallon models. With a tankless model, you can have multiple people take consecutive showers and still have hot water to fill up a large soaking tub while running the dishwasher or washing machine.
  • Save Money – Hot water is hot water but it does make a difference in the ultimate price you pay in energy bills which type of hot water heater you choose. Tankless water heaters, while costing more upfront, allow some homeowners to realize as much as a 40 percent savings on the heating cost, as compared to a traditional storage unit.
  • Save Space – You also need less physical space to install a tankless water heater. With a size that resembles a small suitcase, you can mount one on the wall, in a crawl space, or even under a sink. These benefits alone should give you pause to at least consider upgrading to this technology next time you’re in the market for a water heater.

    how-tankless-water-heater-works

    (click to enlarge)

How does a tankless water heater work?

A tankless water heater is designed to heat water so incredibly fast that you don’t need a storage tank. Once demand is applied, say from someone taking a shower, it’s only then that water starts to flow through the unit. Some models provide a small reservoir tank so you have hot water for the few seconds it takes to heat incoming water on the fly. Cold water comes in from the house’s plumbing, where an igniter fires up a flame that heats the water as it passes through copper tubing. In less time than you would expect, hot water flows out ready to use just as if it came from a storage type heater.

Flow Rate Math

The critical number to consider with a tankless heater is temperature and flow rate. You also need to calculate how many appliances in your home need hot water and how much demand would be put on the system at max capacity. Here are some sample appliances with associated flow rates expressed in gallons per minute (GPM) and the normal temperature desired:

Appliance GPM Temperature
Tub 4.0 102° F
Shower 2.5 104° F
Washing Machine 2.0 120° F
Dishwasher 1.5 110° F
Kitchen Sink 1.5 110° F

Source

If you think you might have a shower, washing machine, and kitchen sink going at the same time, you’ll need a unit that can supply 6 GPM (2.5 + 2.0 + 1.5 = 6.0 GPM). Additionally it needs to be able to raise the water temperature from an average of 40 degrees up to 120 degrees for the washing machine – a rise of 80 degrees. When shopping for a tankless heater, refine your search to those that provide an adequate temperature rise and flow for your needs.

What types of tankless water heaters are there?

Tankless hot water heaters come in three different types: non-condensing, condensing, non-condensing hybrid. Non-condensing and condensing were the first two generations of tankless heaters that have been used in Europe for decades. The non-condensing design uses a primary heat exchanger to heat water, which creates hot exhaust and the necessity to install an expensive vent. A condensing unit employs a second heat exchanger which uses exhaust from the first to further heat the water – a much more efficient design. The hybrid model was created in the United States. By adding a small holding tank that overcomes the inefficiency of short draws, this model is able to develop a true efficiency rating close to .96 (1.00 is perfect).

For those that understand the benefits of a hot water recirculating system, a few tankless models now include an on-board recirculating pump such as the Rinnai RUR98iN (my favorite) and Navien NPE-240-A.

How much does a tankless water heater cost?

As with almost anything you buy, tankless water heaters run the gamut in price from under $1,000 to over $3,000. Some people may not care how much this type of heater actually saves over a storage model, but are only interested in the smaller footprint and “coolness” factor. According to the U.S. Department of Energy, a gas-fired tankless water heater will save you about $108 yearly, while an electric model about $44. You can expect the unit to last 20 years. With a new storage water heater costing in the vicinity of $400-$600, you have some math to do before you make a decision.

What’s the cost to install a tankless water heater?

If your house is already set up for tankless technology, installation costs might not be too bad and in the vicinity of $700-$1,000 (according to Homewyse), but a complete installation could cost $2,000 or more in addition to the cost of the heater. Proper installation requires the following:

  1. Dedicated gas line to handle the 200,000 BTU demand
  2. Category-3 venting; might require unit relocation to exterior wall or outdoors
  3. Additional piping if relocated
  4. Dedicated power supply with battery backup

unlimited-hot-waterAs you can see, installing a tankless water heater is no small feat. If you are planning on a new construction home, it’s usually highly recommended to go with a tankless system if you are even considering it and your budget allows. This is the best time to do so.

The bottom line is that, despite its undeniable efficiency and longer life, the increased cost of installing a tankless water heater might not make it financially feasible right now. Tankless models cost at least three times as much as a storage type. Energy savings might not make it a wise financial decision. Having said that, not all decisions have to be made strictly according to dollars and sense.

As with other new technology, prices of tankless water heaters can be expected to decline as time goes on, aided by deeper market penetration, and more widespread manufacturing. There’s no denying these little units have an aesthetic appeal that storage water heaters could never match. In addition, the efficiency requires less use of open flame and is probably environmentally friendlier to some extent. The bottom line is you just have to decide for yourself what kind of heater you want. There’s no wrong answer.