Cold Shower?

One of the
most common issues with tankless water heaters is the failure to deliver water
at a comfortably warm temperature. This is almost always about the wrongful
decisions of consumers rather than some inherent weakness of tankless water
heaters. Learning about the reasons behind tankless water sizing mistakes is
the best way to avoid those mistakes yourself.

The penchant
for buying the cheapest available product is a strong factor in the mistaken
decisions about the water heater size. People get undersized tankless units
simply because they cost less than the larger, more powerful models. As a
result, the units they install do not have what it takes to raise temperature
of the incoming water to the temperatures needed for showering comfortably  and other purposes. Yet, thrift is not the
only reason behind installing undersized tankless water heaters.

Consumers
sometimes do not pay attention to water temperatures in their town when making
decisions about water heater models. This often happens when they get a
tankless for the first time to replace a storage water heater and they do that
without doing enough research or without seeking guidance from a professional.
Storage water heaters do not have a problem with heating capacity because they
have virtually unlimited time to heat the water. With a conventional hot water
heater, you wait for the thermostat to show 120°F and then take a shower. So,
even if the incoming water is nearly freezing, the water heater will eventually
heat it. A tankless water heater has no such long durations of time for doing
its job. Because it has no tank, the water must be heated instantly before it
flows through the heat exchanger and leaves the device. This means a lot of
heat must be generated in seconds if it is a city with cold water and that can
only be achieved with some of the largest tankless models in the market. People
who do not understand this instantaneous nature of tankless water heaters can
end up getting a small unit in a cold region and complain about cold showers.

It Is BTUs Not Gallons You Are Looking For

There is one
final and important reason behind wrong size choices when getting tankless
water heaters. It is about misleading information provided by manufacturers. Companies
often stress the water flow capacity of their products, which is misleading. A
tankless water heater can be equipped with a large enough pipe to let 8 gallons
of water per minute to run through it but this is by no means an indicator that
all of those 8 gallons will be at a decent temperature without regardless of
the incoming tap water temperatures. The real indicator that a tankless model
is able to heat cold water to whatever temperature you need is the power in
British Thermal Units or simply BTUs.