Factors To Consider When Purchasing a Tankless Water Heater
 1. Flow rate –
While tankless water heaters can provide an endless supply of hot water, they
have a limitation as to how much hot water can be produced at any given time.
There is also a relationship between the amount of hot water produced in
gpm (gallons per minute) and the temperature rise which is listed in our product
comparisons link at the bottom of this page. The
temperature rise refers to the number of degrees the inlet water temperature is
increased. For example, in the US
the average inlet water temperature is 55 degrees, so to raise the water to 115
degrees in this case would require a 60 degree temperature rise.
2.Your
simultaneous water usage needs.
Do you need to run 2 showers at the same time or maybe a shower and a
couple sinks? The chart below shows
the range of water usage range and average water temperatures for various
fixtures. We suggest using 2.5 gpm for a shower and 1.0  gpm for a bathroom
as a reference point in determining your total simultaneous water needs.
For example, if you are running 2
showers at the same time, you will be requesting5 gallons per minute from the
tankless water heater. If you were
running a shower and the washing machine at the same time, you would be
requesting 5 ½ gallons per minute from the water heater.
In either of these situations, you would need something that produces at
least 5-5 ½ gallons per minute (250SX).
|
Fixture |
Average Flow GPM |
Avg. Temp. |
| Tub |
2.5 – 4.0 |
102 F |
|
Shower |
2.5 |
104 F |
|
Washing Machine |
2.0 – 3.0 |
120 F |
|
Bathroom Sink |
1.0 – 2.0 |
110 F |
|
Kitchen
Sink |
1.0 – 2.0 |
110 F |
Note:
tankless water heaters are intended to heat potable (drinking) water only and the
inlet water to a tankless unit should not be pre-heated.
The Bosch 125/250 series (gas) and PowerStar AE125(electric) tankless
units are meant to be installed as a whole house water heater.
If you are wanting to have instant hot water at a sink while using a
tank, we suggest installing a small electric tank such as an Ariston GL series
or a Grundfos UP15 instant hot water pump.
 3. Gas
vs. Electric – if you have
a choice between gas and electric, we suggest the gas units as they are
typically more powerful than the electric units and are more energy efficient.
The most important elements for a gas installation have to do with the
venting, proper gas line sizing and combustion air requirements.
The electric tankless water
heaters are hard wired and typically have high amperage requirements, however
there are no combustion air or venting requirements with an electric unit.
How do I find the right tankless water heater? We've
created a simple shopping consultant to match you with the best products to take
care of your needs. Simply answer the each question as best as you can and we'll
provide you with a listing of products that best fit your needs.
Click here to start
What do others have to say?
Department of Energy Study: Water heating accounts for 20% or more
of an average household’s annual energy expenditures.
Read More
Additional Information on Tankless Water
Heaters?
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