Tankless Advantage
THE KELTECH TANKLESS ADVANTAGE: EXECUTIVE SUMMARY
Energy Efficient Water Heating
Tankless water heaters are energy
efficient solutions for many commercial applications. Because
they perform on demand, there is no energy draw when they are
not in use. That makes tankless water heaters an ideal solution
for most businesses that don’t
need to run hot water continuously 24/7/365.
Precise Temperature
Control
Not all tankless water heaters are created
equal. All tankless water heaters quickly increase water temperature.
Keltech’s
tankless water heater control system can heat water accurately to within
+/- 1ºF for applications that demand precision. The
controller can also maintain a steady temperature range for
applications that require it.
Correctly Specifying or Sizing a
Tankless Water Heater
Rightsizing your tankless water heating
solution is critical. There are many variables that affect the
correct sizing of a tankless water heater but the three most
common are flow rate, temperature rise and your local utility’s
power options and capacity. Exceed the unit’s flow capacity
and temperature output decreases.
The Keltech Tankless Advantage: Efficiency
Defined
Dieter Lutz — Marketing
Director, Keltech, Inc.
There are many reasons to consider specifying
a tankless water heater for an initial build or retrofit in a
commercial or industrial application but there is one over riding
reason: efficiency.
Tankless water heaters operate efficiently
because they only draw energy when needed.
Temperature controlled
units heat directly to a set-point temperature and expend only
the energy needed to reach and maintain it.
By comparison, boilers
expend a lot of energy to heat water above usage temperature,
continuously serving recirculation loops or boosting storage
tanks. Often the hot water must be overheated then cooled through
a mixing valve to reach the desired temperature.
Simply put, tankless
water heaters are energy efficient. Energy is only drawn when
hot water is needed, and then only the energy required to reach
the desired temperature is consumed.
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HOT WATER ON DEMAND
To truly understand why
a tankless water heater is so efficient, one must understand
how it functions.
When hot water is needed, a flow sensor registers
the demand. It activates the temperature controller that takes
water temperature readings inside the heat exchanger as the water
is flowing through it.
If the temperature of the water is lower
than the set-point temperature the heating elements energize.
In
all of our models this process happens within 2 seconds or less.
The
energized elements begin to rapidly increase the water temperature
driving the outlet temperature quickly toward set-point.
Up to
this stage, most electric tankless water heaters on the market
are nearly identical in function. From this point forward, control
theories and design vary greatly and sometimes performance follows
suit.
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KELTECH’S TANKLESS ADVANTAGE TO
THE NTH DEGREE:
PRECISE TEMPERATURE CONTROL
Keltech’s tankless water heater control process
works as follows: As the temperature increases from startup,
the controller monitors the output temperature and weighs the
energy available and requirements against the set-point temperature.
This
temperature rise is controlled, and curves to set-point are predicted,
evaluated and changed based on speed of temperature increase.
This
data is then used to predict time-to-temperature and stabilize
the temperature rise through a modulated duty cycle that provides
the exact amount of energy required to meet your temperature
setting.
Many Keltech tankless water heater models can reach
set-point and stabilize within +/- 1ºF, and maintain that
temperature for the duration of the process.
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CONTINUOUS TEMPERATURE
CONTROL THROUGHOUT THE HEATING PROCESS
Once set-point temperature is reached, the
controller constantly monitors output temperature against the
set-point and can vary amperage to the elements, sometimes as
fast as 120 times a second. Other factors are sometimes monitored
in control systems to calculate the energy needed. Should the
incoming water temperature vary or flow change drastically, the
controller must quickly recalculate this energy need and deliver
the proper amperage to the heating elements. The speed at which
this calculation happens plays a great role in customer satisfaction
and output temperature stability.
As flow rate through a tankless
water heater increases, so does the duty cycle commanded by the
controller. The unit can accommodate this increase in flow until
energy demands exceed the capacity of the unit. Once the controller
reaches 100% duty cycle at set-point temperature, any further
increase in flow will have a corresponding decrease in output
temperature. This is why correctly sizing a tankless water heater
is critical.
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HOW TO SPECIFY OR RIGHTSIZE YOUR TANKLESS WATER
HEATER
Correctly sizing a tankless water heater requires
three variables common to any project:
- Flow rate
- Temperature rise
- Available local utilities
When calculating the flow rate, all aspects
of the project must be considered. A unit dedicated to a single
process or fixture simplifies the process greatly.
However, when
specing multiple fixtures or processes, total flow becomes slightly
more complicated. In these instances, maximum potential flow
rates should be dictated by the sum of connected fixtures if
simultaneously in use.
Desired temperature rise should not be
confused with process or set-point temperature. Temperature
rise, commonly referred to as delta “T,” is the
difference between incoming water temperature and desired set-point
temperature.
This difference can vary greatly due
to variance in regional ground water temperature, storage,
or the possibility of a “boosted” supply.
For sizing purposes, the lowest potential incoming water temperature
should be factored.
When calculating necessary set-point temperature,
be sure to factor in heat losses within the delivery to the process
or fixture if precise temperature is required.
Once these numbers
are established, the difference is the maximum delta “T” for
your project.
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Properly Sizing or Specing Your Tankless Water
Heater
- Flow rate (GPM)
- Temperature rise ( T ºF)
To determine the size and kilowatt
rating you need, apply this formula:
The result of this formula
is the maximum kW needed to accomplish your project requirements
for on-demand heated water. Other media will vary slightly. This
formula is a nearly universal method of calculation for energy
input to yield temperature at required water flow.
Your kW requirements
in conjunction with your local electric utility’s power
capacity provide the foundation for sizing and specifying a tankless
water heater. Your local utility’s
ability to support peak needs must also be taken into consideration.
Keltech’s trained sales engineers are ready to work with
specifying engineers at any point during this process.
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A Quick
Note on Utilities:
Keltech manufactures electric tankless water
heaters. The following calculations will be based on results
yielding a kW requirement. This can be easily converted to Btu/h
if sizing for a gas tankless water heater.
Voltage availability
should be considered in the final application. Keltech tankless
water heaters accommodate the most common service voltages in
the world. Our product line voltage range extends from 208V single
phase to 600V 3-phase delta.
Once flow rate and temperature rise
are established, these variables can be added to the sizing formula
below to determine the maximum kW output required for the project.
Achieving maximum kW can be accomplished with a single unit
or by pairing multiple units together. Keltech’s single
unit product line ranges from 3kW to 144kW.
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THE TRUTH ABOUT TANKLESS:
WHAT CAN YOU BELIEVE?
Can Tankless Hot Water Heaters Provide Instantaneous
Hot Water?
No. The use of the word “instantaneous” is
a misnomer and should be discontinued. A more appropriate phrase
is “on-demand.” Tankless
water heaters perform on-demand and can deliver hot water within
seconds – not instantaneously.
The water still has to be heated within the
unit (time-to-temperature) and then there is the distance of
plumbing runs. The truth: tankless water heaters perform on-demand
and deliver hot water within seconds not instantaneously.
Can
Tankless Water Heaters Provide an Unlimited Flow of Hot Water?
Only
if the project is specified correctly. With correct sizing, you
could have an unlimited and continuous flow of hot water. If
realistic consumption requirements are considered and factored
into the specification, the end result is a water heating solution
with enough capacity to meet the needs of most projects. To properly
specify a tankless water heater, please refer to our sizing formula.
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What
is More Energy Efficient: A Boiler or a Tankless Water Heater?
There
is no universal ratings system or standard established or adopted
for testing and comparing energy efficiency between boilers and
tankless solutions. Many rating systems with sound engineering
calculations and solid test criteria currently exist. Unfortunately,
measurable attributes vary, as do conclusions. In our opinion,
the inherent advantage of on-demand water heating in a direct-heat
electric configuration makes a compelling argument. Power on.
Power off.
Is There a Tankless Disadvantage When it Comes
to Applications?
Tankless systems may yield less than desirable
results where pulsed flow process cycles are fed directly from
the unit in 3-15 second intervals and precise temperature delivery
is required. Pulsed flow cycles are common in sporadic spray
wash processes.
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The quick timing intervals do not permit the
control to raise and fully stabilize the water temperature before
the cycle terminates. Subsequent activations may allow the control
to erroneously factor latent heat from the heating elements into
its next duty cycle. The probability of variable temperature
output would likely be less than desirable in this type of application.
Is
There a Workaround for a Sporadic Spray Wash Process?
Yes. While
not impossible to meet this need utilizing today’s
technology and direct plumbing from a tankless unit (the process
would need to be carefully evaluated and control programming
specific to its application would be required), a more reasonable
solution would be to install a recirculation loop with an appropriately
sized tankless unit, or provide the process with another (secondary)
source of hot water.
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THE KELTECH TANKLESS ADVANTAGE:
ENERGY EFFICIENCY. PRECISE TEMPERATURE CONTROL.
The advantages
of heating water on-demand with a Keltech tankless solution are
clear. Energy is only consumed when demand necessitates it. The
amount of energy expended is equal to the requirement of the
need. The energy is released, timed to requirement, and waste
is minimized as the water is consumed immediately after the expenditure.
The next time your engineering firm specifies
a water or fluid heating process, consider a Keltech tankless
solution.
ABOUT KELTECH TANKLESS WATER HEATERS
Keltech,
Inc. engineers and manufactures tankless water heaters that perform
on demand.
Custom built to meet temperature and flow rate
specifications, Keltech process heaters provide continuous hot
water with precise temperature control for commercial as
well as large and light
industrial applications.
Keltech also produces sporadic water heating
solutions for safety shower and emergency
eyewash applications,
hot water delivery systems for the IntegriFill™ market, and other
commercial applications.
Keltech manufactures water heating solutions
for the following applications: de-ionized water, reverse osmosis
processing, corrosive fluid heating protection, and non-flammable
fluid heating.
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TANKLESS APPLICATIONS
Tankless water heaters
seamlessly integrate into many diverse applications and provide
reliable, efficient service. Continuous duty heating applications
yield great efficiency, especially in direct-heat electric configurations.
Examples of tankless water heating solutions for continuous
duty or process heating applications:
- Parts washing
- De-ionized (pure)
water heating
- Consumables requiring FDA approval
- Heating
corrosive or caustic non-flammable liquids
- Reverse osmosis
(R/O) heating applications requiring precise temperature
- Rinsing
printed circuit boards
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Examples of Sporadic Applications
The measure
of tankless energy efficiency increases greatly in applications
that require sporadic use. Power on. Power off. Down time has
no utility cost. Providing ANSI compliant tepid water for a safety
shower application is one example of a sporadic process where
on-demand heating can save a great deal on utilities. Aside from
the possibility of a chemical injury incident and ANSI mandated
testing, tankless safety shower heater utility costs are minimized.
The
tankless advantage with sporadic heating applications is clear.
Power on. Power off. Continuously heating water, storing heated
water and the associated costs of standby heat losses are not
necessary when tankless water heaters are specified. Boiler fed
recirculation loops to mixing valves are not necessary to install
or maintain.
Examples of other tankless water heating solutions
for sporadic applications:
- Booster heaters to sterilize medical
equipment
- Point-of-use heaters for commercial dishwashers
- Utility
closets or janitorial closets
- Scientific, chemistry, pharmaceutical
laboratories
- Chemical heating jackets
- Fluid heating
solutions
- Radiant heating systems
Download Dieter Lutz's whitepaper on Tankless Advantages now!
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