Energy-saving Waterheaters

Aaron Golden

09/01/2009

Water Heaters

Obviously there is a lot of detail that goes into building a home from scratch.  Habitat houses feature a tankless water heater; below you will find the pros and cons, along with an evaluation of efficiency of the tankless water heaters.

How tankless heaters work is a fairly simple process.  When a hot water tap is turned on, the water enters the heater; there is then a water flow sensor that will detect the water flow.  The computer, within the heater, automatically ignites the burner.  Water Circulates through the heat exchanger which in turn heats the water to the designated temperature.  When the tap is turned off the unit shuts down.  Since it is a process to heat the water, a little bit of time needs to be allowed from the time a tap is turned on until hot water is produced, however only a small amount of time is needed, and once the hot water comes through, you can expect for hot water to remain.  Habitat houses in McLean County feature these tankless water heaters.  We advertise them as a benefit; they are cost efficient in new houses, but can also be beneficial when converting older homes.

Through various sources, information regarding price estimates, as to how much it would cost for the water heater itself, installation cost, as well as how much it would cost to drain the system was attained.  The first source for information that was obtained was D & R Plumbing.  We sent in a pseudo client, who acted as a buyer, in order to obtain information.  The representative from D & R plumbing, as a good sales representative should do, spent some time trying to convince our client to purchase a “Vortex” water heater, which was twice the price of the tankless water heaters used by Habitat.  Since other sources have already confirmed the water heaters used by Habitat to be very efficient for the size of families that would be dwelling in the homes, this proposal was ignored.  The D & R representative did inform our client it is important to have the tankless water heaters drained once a year, and the cost to drain is roughly $85.00.

There are pros and cons to every decision and purchase that can be made, but given what Habitat for Humanity aims to do, evidence supports that tankless water heaters is the way to go.  The representative from D & R plumbing recommended the “Vortex” water heater because he didn’t quite understand the conditions of the home that is being worked on.  The problem with tankless water heaters is in the longevity of supply; if multiple water appliances are being run at the same time, hot water will not last very long.  For a larger home consisting of 3 bathrooms or more and a family of 5 or more, a tankless water heater probably wouldn’t be as efficient.  Therefore, it may be more beneficial for that family to spend the extra money on a water heater to better fit their personal needs.  However in the cast of a Habitat home, the tankless water heater is the logical approach.  There may be times where hot water starts to run a little short, for instance, if everyone in the house takes back to back showers while someone else is running the sink.  It is well worth using tankless water heaters in Habitat Homes, and save the extra few bucks. 

It is important to locate your tankless heaters as close as possible to the faucets. The extra time it takes the tankless unit to start heating water will be noticeable and perhaps annoying. The large amount of water stored in the pipes also causes a larger "cold water sandwich."

If you are replacing a tanked water heater with a tankless and leaving the piping the same, then you'll notice an increased delay for hot water to reach your faucet. In a tanked system, the water leaving the heater is already hot, so you only have to suffer the delay caused by the piping. In a tankless system, however, the water in the heater is cold, so the heater has to turn on and get itself up to temperature before the water flowing out is hot or even warm. So, where it used to take about 40 seconds for hot water to reach our master bathroom shower, it now takes about a minute with the tankless heater.  Tankless heaters are more expensive than tanked heaters because they are more complex, but the gas-fired units are more efficient and cost less to run.  According to the Payback Calculator at Mattox.com, it costs roughly $1250 to install a Tanked water heater versus $2400 for a tankless water heater.  Although tankless heaters are more expensive, they also will be saving just over $75 a year in total energy savings a year, thus in just under 15 years, the tankless heater will recover the extra cost.

When you put all of the figures together: the water heater itself runs $2400 (which includes installation), and it costs an additional $85 to drain it once a year.  The Higher efficiency and lower long term costs makes this price well worth the cause.  Not to mention, unlike the tanked water heater, the tankless water heater does not have a continuous pilot light, which results in no wasted gas.  Furthermore, the tankless water heaters only run when water is flowing, which makes it a much quieter and more peaceful machine.

When considering all the factors that we are working with for this project, it is clear that tankless water heaters are the most efficient option.  The only negative argument for tankless water heaters is if the family does not intend to live in the home year round, which in a Habitat development is not the case.  Tankless may not even be the cheapest option; however it certainly is not the most expensive either.  With just 1 bath and an average sized household, the family that will dwell in this home will incur very little issues in hot water output.