Operation; General; Turning It On; Turning It Off - Takagi T-KD20 Installation Manual And Owner's Manual

Operation

General

The Flash Water Heater is an instantaneous, tankless
water heater designed to efficiently supply domestic or
commercial hot water and space heating applications.
The principle behind the Flash water heater is simple:
Once a hot water tap is opened, the Flash's flow sensor
detects that hot water is needed, and automatically
commands the computer to electronically ignite the
burners, and heat water. During operation, the
computer monitors the water temperature and flow rate,
and controls the gas flow and fan speed to maintain a
constant output temperature. After the burners are
ignited the "fire on" lamp will be lit.
0.75 gallons per minute is required to turn the burner on,
but after the burner are ignited, the flow rate can drop to
0.6 gallons per minute without the burner turning off.
As long as water, gas and electricity are connected,
there will be an endless flow of hot water. To turn on
your water heater, just open a tap. To turn the heater off,
just close the tap.

Turning It On

To turn on the Flash water heater
1. Open a hot water tap, or turn on water demanding
appliance.
2. Unit will detect flow, burners will ignite, "Fire On"
lamp will light up.
3. If necessary, mix in cold water to get a comfortable

temperature.

Turning It Off

To turn off the Flash water heater
1. Close the hot water tap, or turn appliance off.
2. Flow will diminish, unit will shut off.
3. "Fire On" lamp will go out.
Temperature
The output temperature of the T-KD20 has been factory
set for a maximum 120° F (50° C). This is electronically
controlled by the computer and can be adjusted with a
TK-RE01 temperature controller, or with the dipswitches
on the computer board (See pgs. 21-22 for dipswitch
settings). Further adjustment may be made by mixing in
cold water with the hot to obtain the ideal water
temperature.
The flow rate possible out of the unit is dependent on
the temperature setting chosen. Consult the flow charts
on the last page of this unit to determine the possible
outlet temperature and flow rate combinations.
WARNING: Temperatures above 125º F (52º C) can
cause severe burns or death from scalding. Children,
the disabled and the elderly are at a high risk of being
injured. Feel the water temperature before bathing or
showering. Do not leave children, disabled persons, or
the elderly unsupervised.

Flow

The flow rate through the T-KD20 is limited to a
maximum of 6.9 GPM. The temperature setting, along
with the supply temperature of the water will determine
the flow rate the unit puts out. Consult the flow charts
on the last page of this manual to determine the
possible outlet temperature and flow rate combinations.
Based on the United States Department of Energy
method of testing water heater output, the T-KD20 is
rated for 250 gallons per hour, or 4.2 GPM, at a 77° F
rise above the inlet temperature. Refer to the following
chart of typical household flow rates to determine what
the T-KD20 can do in a household application.
Remember that for bathing, cold water will be mixed for
a comfortable temperature, increasing the flow output
rate.
Household Flow Rates
Appliance / Use
Lavatory Faucet
Bath Tub
Shower
Kitchen Sink
Dishwasher
Washing Machine
Taken from UPC 1997
Flow Rate
(GPM)
1.0
4.0
2.0
1.5
1.5
2.0