When to Buy an Instantaneous Water Heater (and When Not To)
In many ways, we are living in the future. We have wireless internet, artificial intelligence and holographic KISS concerts . Technology moves so quickly that it is often difficult to keep up with it: once you have mastered one new paradigm, a dozen others appear while you are not paying attention.
But not everything in our lives has gotten better or even changed that much. Your standard water heater , for example, is fairly primitive: a tank of water with a fire underneath it or electric heating elements inside the tank. It’s not that difficult and it’s not that far from a bucket hanging over a fire.
There is a more advanced, modern option: instantaneous water heater , also known as an on-demand water heater. These devices eliminate the need for a tank altogether, heating water on demand. Not only are they up to 34% more energy efficient, but they also offer the enticing option of endless hot water and endless hot showers. However, despite these advantages, a tankless water heater is not suitable for everyone or in every living situation.
Capacity
Tankless water heaters can supply endless hot water in the sense that they do not rely on a specific amount of stored heated water. But they are not magicians – they can only heat a certain amount of water so quickly. Every tankless water heater has a flow rate , measured in gallons per minute (gpm), and every appliance that provides hot water (faucets, showers, dishwashers, laundry) also has a flow rate . Your tankless water heater must have a flow rate that is sufficient to supply hot water to all appliances at the same time.
For example, if someone in your household showers frequently (2 GPM) while the washing machine (3 GPM) and dishwasher (2 GPM) are running, your tankless water heater should be able to produce at least 7 GPM. minute. A heater with a higher flow rate will cost more, and if you have times when your hot water usage is higher than normal, your tankless water heater may not be up to the task.
Another factor affecting the performance of an instantaneous water heater is the increase in temperature. This is the difference between the temperature of the water when it enters your home through the pipes and the desired temperature of the hot water. If the groundwater temperature is 50 ºF (10 ºC) and you want the hot water temperature to be 120 ºF (49 ºC), you need a temperature increase of 70 ºF (39 ºC). If for any reason the incoming water temperature drops a few degrees, your tankless water heater may struggle to provide hot enough water for your needs, especially if you use many appliances and fixtures at once.
This means that if you have a large family or a lot of hot water in your home, a tankless water heater may not be the best choice, even if you carefully calculate its capacity. And since tankless models have no water reserve and rely on a constant water intake, any buildup of minerals in the pipes or drop in water pressure in your home can result in lukewarm water or not having hot enough water. A storage water heater will fill over time even with low water pressure and will eventually heat any temperature water to your desired temperature. But if your hot water usage increases infrequently and the temperature rise is manageable, a tankless unit is fine.
Space
While tankless water heaters are smaller than traditional water heaters (and you can buy compact units designed for smaller spaces), that doesn’t mean you can necessarily fit them into your existing mechanical space. Depending on the power you need, if you have a tight mechanical room or room, you may not be able to squeeze it in and you will have the option of installing it outside the house or in plain sight elsewhere in the house. I personally know someone who had to install it in their living room, so now they have a huge unit with pipes running all over the place, right in the middle of their house. And choosing a smaller unit may mean sacrificing performance, leaving you with chronically warm water.
It’s best to check with your plumber or contractor to make sure they can install a tankless water heater in your home before you decide to purchase one. If not, but you can tolerate having it on display for guests or installed outdoors, then a tankless unit is still a good option for you.
return on investment
The final consideration when choosing tankless water heaters is the return on investment. Because of their superior energy efficiency, tankless water heaters are often touted as a smart investment that will get you your money back in the long run. Tankless water heaters can last 20 years or more (more than twice as long as a conventional storage water heater), and they can save the average family of four about $100 a year on their energy bills. If your tankless water heater lasts 20 years, you’ll save $2,000 over its lifespan. The cost to install one of these units ranges from $1,500 to $3,200 (including labor), so you could get all or at least most of your money back.
But if you don’t plan to stay in your home that long, the investment may not be worth it. If you plan to sell your home in a few years, a tankless water heater may appeal to some potential buyers, but there is no data to support the idea that a tankless water heater makes a significant difference to a home’s value one way or the other. On the other hand, if you’re living in your forever home or don’t plan on moving anytime soon, the combination of endless hot water and energy efficiency will pay off.