Posted on: October 27, 2016
By: Alan O'Neill
Posted in: Plumbing
Water heating is the second largest energy use in residential homes in the USA. It is also a very inefficient use of energy, with typical equipment efficiencies around 60%. A whole-house tankless water heater can reduce your water-heating bill by 5 percent to 50 percent or more.
Water heaters are something you probably don’t think about until you need to replace one. Depending on how old your water heater is, you may not be able to get the same model you had—or even want to. Upgrades in design and energy efficiency have changed the options on the water heating market. A tankless water heater may be a good option for facilities who want a more energy efficient way to heat their water, and take up less space.
Here’s how to decide whether making the switch makes sense for your household and, if so, how to shop for such an important upgrade.
Will you save enough energy by installing a tankless water heater to justify the high cost of the equipment? According to Minnesota researchers, the answer is: probably not.
Although tankless water heaters are, on average, more efficient than traditional tank-style water heaters, they’re also more expensive — so expensive, in fact, that many potential customers wonder whether their high cost can ever be justified by likely energy savings.
Before you can decide whether to buy a tankless water heater, you’ll need to know how much energy you’ll save. Can you trust the information provided by tankless water heater manufacturers — for example, the estimate from Rinnai’s online calculator that you’ll save $178 per year?
Before I get around to answering that question in detail, suffice it to say: probably not.
To figure out the payback period for the incremental cost of a tankless water heater, it would be useful to know:
To find the answers to all of these questions, a group of researchers in Minnesota undertook a monitoring study to measure the performance of tank-type and tankless water heaters in actual homes. The researchers concluded that most tankless water heaters will fall apart from old age before they save enough energy to justify their high cost.
The researchers — Dave Bohac, Ben Schoenbauer, and Martha Hewett of the Center for Energy and Environment in Minneapolis, along with Tom Butcher of Brookhaven National Laboratory and Mary Sue Lobenstein of Lobenstein Consulting — monitored water heaters in ten homes for over a year. Their data have been published in a report, “Actual Savings and Performance of Natural Gas Tankless Water Heaters”.
The ten families enrolled in the study were chosen based on household size. The number of people in these families matched the household size distribution shown in the census data for the Minnesota in 2000: two homes had 1 resident each, three homes had 2 residents, two homes had 3 residents, two homes had 4 residents, and one home had 5 residents.
A total of twenty-four water heaters were installed in the ten homes; each home got at least two water heaters. Eight homes got a tank-type water heater (an A.O. Smith GCV40 40-gallon natural gas water heater with atmospheric venting). In addition, each home got at least one natural gas tankless water heater. Ten tankless water heaters were tested; a variety of models were chosen from among those sold by five manufacturers (Bosch, Noritz, Rheem, Rinnai, and Takagi). The researchers did not test any electric tankless models.
Monitoring equipment for each test set-up included a dedicated gas meter, a dedicated water meter, and temperature sensors that measured the temperature of the incoming water as well as the temperature of the hot water. (The incoming water temperatures varied seasonally by about 30°F to 35°F.)
At each house, researchers adjusted gas and water valves to alternate between the tank-type water heater and the tankless water heater at monthly intervals. Only one water heater was used at a time. The changeover schedule was adjusted at each site so that every tested heater operated over the full seasonal spectrum of incoming water temperatures and outdoor air temperatures. An average of 363 days of useful data were collected from each home. Read more here.
Pick the water heater that best fits your water usage, lifestyle situation, and budget. So if you can handle the high initial costs, you can save more money in the long run by switching to tankless. Tankless can also be a good choice for large families because you have more people consistently using more hot water. If you need to upgrade or replace your old water heater, going tankless might be a good option for you.
It can be complicated removing old water heaters because they can weigh over 150 pounds and can release scalding hot water if handled improperly. Our service professionals are trained and experienced in installing tankless water heaters. We will take care of all your electrical demands so that your tankless water heater will be seamlessly installed. Call (713) 812-7070 us for your home service and repair needs.
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