We’ve all had occasion to curse the hot water heater, right? A hot shower suddenly goes cold. A relaxing bubble bath goes awry when the hot water runs out before the tub is half full. Having to remember to coordinate showers and other hot-water applications to make sure nobody suffers can be a pain. You may have heard that tankless water heaters provide an uninterrupted and endless supply of hot water. Additionally, tankless water heaters can save money on your energy bill by eliminating the constant heating and reheating of water waiting to be used. If you’re thinking of replacing your old hot water heater with a newer tankless model, take a few moments to understand the basic functions and potential drawbacks before you go shopping.
Traditional water heaters store water in a tank. Your electricity or gas kicks on to heat this water to your desired temperature. Once this temperature is reached, the heating process stops, which causes the stored water to cool slowly until the electricity or gas comes back on and starts the process all over again, which results in energy (and money) being wasted to constantly heat and reheat unused water. When you turn on the hot water in your house, this preheated water flows to your faucet. The tank then refills, and the heating and cooling cycle begins again. If you’re trying to use more hot water than your tank can keep up with, you run out of hot water and have to wait for the tank to refill and get reheated.
Most tankless water heaters do not store water, eliminating the wasted energy required to keep a full tank of water hot. The lack of a tank also means there’s no running out of water midway through a shower.
In theory, tankless hot water heaters seem like a great alternative to the older tank models. In actuality, though, they do present challenges that you need to consider before taking the plunge and spending the extra cash that one of these will cost in comparison to a tank model.
One thing worth noting is that instant heating doesn’t mean instant delivery. How long it takes for hot water to come out of the faucet depends on how far away it is from the source, no matter what kind of water heater you have.
If your goal is to be able to run unlimited hot water applications simultaneously, you might be surprised to learn that the average tankless heater won’t solve that problem. Tankless units are small enough that they generally can’t handle enough water flow to power too many hot water jobs at once. Hot water might flow to all areas, but water pressure is likely to be greatly reduced. Make sure you understand how well any models you contemplate handle multitasking. It is possible to use multiple units running parallel to one another, but the cost of multiple units can be considerable.
The biggest drawback to a tankless system is something called the “cold water sandwich.” This occurs when you get the residual hot water in the line first, then a patch of cold, then the heated water. Some models have developed a recirculation system or mini-tank that helps eliminate this problem.
Another thing to research when comparing tankless models is how much maintenance is required, and how well the models handle sediment.
Original tankless models could be quite difficult and costly to install since they did not work with any of your original hot water tank connections. They also were more expensive to maintain, with replacement parts being expensive and hard to get. Newer models, though, are easier to retrofit and maintain, but still generally are a little more work than upright tank models.
In terms of energy efficiency, tankless models do perform better than their older counterparts, especially in homes with lower water usage. Regardless of the amount of household water usage, spending the extra money to have a tankless water heater at each water outlet can save you 50% over tanked models, but will definitely get pricey enough on the front end that it will take years to see equal energy savings