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  • Writer's pictureJohn@LiteHouse

Pros and cons of tankless water heaters

More and more, the inspectors at LiteHouse Inspect are finding tankless water heaters installed in our Cincinnati Home Inspections.


Tankless water heaters, also known as on-demand water heaters, are very popular among newer homeowners, and for good reason. A tankless water heater does not have a tank (which is fine). Instead of slowly heating the water in the tank to keep the water in the tank warm, the tankless water heater heats only the water it needs very quickly. Most water heaters manufactured today are very efficient direct valve units. Also, while all traditional tank water heaters are very similar, tankless water heaters are not. They are all so different that I have to discuss them in general in this blog post.



Advantages of a tankless water heater


One of the advantages of tankless water heaters is their small size. Instead of taking up a lot of floor space, tankless water heaters are wall mounted.


Another great advantage is the unlimited supply of hot water. You can shower for 5 hours and never run out of hot water. If you have a hot tub, you can fill the entire tub with hot water until it's ready to use.


Perhaps the biggest advantage that tankless water heaters offer is reduced energy consumption. Since there is no hot water tank that needs to be hot all the time, tankless water heaters do not experience as much standby energy waste as traditional water heaters.


Tankless water heaters also last longer, and the warranty on heat exchangers is usually 12 to 15 years. Powervent water heaters usually come with a 6 year warranty, while traditional tank water heaters usually come with a 6, 9 or 12 year warranty.


Disadvantages of tankless water heater


The most obvious drawback of tankless water heaters is the high cost of the device and its installation. Tankless water heaters are more expensive than traditional tank water heaters. Usually about double the price of the unit alone depending on the flow required. They are also more difficult to install because they have special ventilation requirements and often require larger gas lines due to their higher BTU rating. Of course, this means a higher price for installation.



Tankless water heaters can provide an unlimited amount of hot water, but there is a limit to how much water can be provided at one time. A conventional water heater can provide as much hot water as the pipe can handle at one time. On the other hand, tankless water heaters must heat the water as it passes through. It is important to get a tankless water heater that is large enough to ensure that an adequate hot water flow is available. In a cold climate like where the groundwater temperature is low, a small tankless water heater will only provide enough hot water for one shower. Time. As long as you have a large enough water heater installed you should be fine.


Tankless water heaters take a long time to get hot water. A conventional water heater has hot water at the top of the tank and is ready to use. In a tankless unit, cold water enters the heat exchanger tubes and begins to heat up. Any water in the pipes that has cooled since the last ignition of the appliance is delivered to the fixture first. This makes tankless water heaters take longer to deliver hot water. One solution to the long wait time is to install a small tank water heater after the tankless water heater to act as a temperature conditioning tank, but doing so would not be a true tankless system. Another solution is to install a circulation system to make hot water available during peak hours of the day.


Because of the way tankless water heaters heat water, if you turn the hot water on, turn it off, and turn it back on, you'll often end up with a pool of cold water. This does not happen in conventional water heaters.


One of the biggest disadvantages of tankless water heaters is that hard water damages them. Damage caused by lime, accumulation of minerals or sediment is not covered by the manufacturer's warranty.


To prevent premature damage, tankless water heaters must be flushed regularly.


Tankless water heaters are also supposed to be drained monthly and the filters cleaned.


Another drawback of tankless water heaters is the use of electricity. This will increase the installation cost if outlets need to be installed. This also means that there are more opportunities to make mistakes. Check the list of error codes for your specific tankless water heater.


Low flow = no hot water.


A tankless water heater needs a constant flow to keep the water heater running. For example, some units only operate with a water flow of 1/2 gallon per minute. I've heard this can be a big problem in older homes with galvanized water pipes that can't even handle a 1/2 gallon per minute flow rate.



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