Introduction of Constant Temperature Water Heater Control System
 
 

I. Company profile
Please read this Manual carefully before installation and use of product to ensure its best performance.
The control system of DMD series intelligent digital constant-temperature gas water heater (hereinafter referred to as the control system) is composed of four parts, namely a rotor gas governor valve, a display, a controller (including an igniter) and an electric water valve, wherein the rotor gas governor valve and the electric valve have applied many patented and proprietary technologies newly developed, and the control mode has adopted the steam-water-power fuzzy control technology.
Unlike those with ordinary fully automatic control mode, gas water heaters equipped with such intelligent digital constant-temperature gas water heater control system have created favorable conditions for the development of instantaneous gas water heaters towards safety, reliability, comfort, convenience, energy conservation and cheapness.
Safety: By providing multiple protections, the control system performs patrol inspection of the water heater during stand-by and running states, and will activate protection whenever necessary to secure safety of users.
Reliability: After years of development and production, the control system has acquired certain degree of reliability: Strong adaptability to supply voltage and the applied electronic regulation technology makes gas fluctuation more adaptable; the electric water valve makes the control system adaptable to a wider scope of water pressure, greatly improving the environmental suitability and reliability of water heaters.
Comfort: Extreme low temperature rise when water is off, short heating time, short convergence time and small temperature fluctuation.
Convenience: All users have to do is to turn on the tap and set the desired temperature, and hot water will come out, in any season and at anywhere.
Energy conservation: Apart from the marvelous performance of the control system which helps minimize the consumption of water and gas during the standby time, the small power dissipation and standby dissipation of the control system during working can also save users a lot of electric energy.
Cheapness: The control system in itself is cheaper than other systems; besides, its small size also enables smaller and more conservative design of water heaters.

II. Work principle and functions

  1. Hot bath instructions (constant temperature)
    1. Connect power supply and press “ON/OFF” once, and the control system enters into standby state.
    2. Turn on the water switch, various state indicators will turn on; water, gas and wind go to the water heater; and the controller is automatically ignited.
    3. Temperature preset: When the water heater is connected to power supply for the first time, the preset temperature is automatically set at 42℃; press ▲ or ▼ to change the preset temperature of hot water. When the water heater is turned on next time, the automatic preset temperature shall that set last time.
  2. Cold bath instructions

When the water heater is in OFF state, turn on the water switch to have cold bath

  1. Timing shutdown

After 20min working on end, the system will be automatically shutdown.

  1. Protection device

The system performs automatic inspection before startup and during operation, and will automatically shutdown in case of any occasions that may harm users.

  1. Auto-control over staged combustion

If the minimum thermal load when combustor of the water heater becomes stable in combustion still fails to meet operating requirements, staged combustion control can be applied, i.e. when thermal load decreases to certain degree, the system will automatically reduce the number of burners; when thermal load rises to certain degree, the system will automatically increase the number of burners, in order to realize automatic switching of staged combustion, enabling a minimum temperature rise of 4℃.
III. Safety performance
This system has following safety functions:

        1. Safe shutdown in case of ignition failure;
        2. Safe shutdown in case of unexpected stall;
        3. Safe shutdown in case of open-circuit of wind pressure switch;
        4. Safe shutdown in case of open-circuit or short-circuit of sensor;
        5. Safe shutdown in case of open-circuit or short-circuit of coil of rotor solenoid valve;
        6. Safe shutdown in case water temperature is detected over 75℃;
        7. Safe shutdown in case of failure of controller program;
        8. Normal operation or safe shutdown in case of sharp decrease power voltage.

Error codes:


E1:

Ignition failure

E2:

Unexpected stall

E3:

Switch of gas rotor valve fails

E4:

Governor of gas rotor valve fails

E5:

Over temperature (≥75℃)

E6:

Open circuit, short circuit or failure of temperature sensor

E7:

Ventilation failure

 

 

IV. Technical indexes of control system

  1. Service conditions:

1)Gas type: Liquefied petroleum gas, natural gas, manufactured gas;
2)Applicable water pressure: ≤0.5Mpa

  1. Rated working voltage: AC220V
  2. Operating voltage range: AC180V ~ AC250V
  3. Standby dissipation of control system: ≤8W
  4. Temperature of storage environment: -20℃~75℃
  5. Temperature of service environment: 0℃~75℃
  6. Maximum RH: 95%
  7. Pulse delay time: 3S+3S
  8. Pulse discharge frequency: ≥8Hz
  9. Pulse discharge distance: ≥5.0mm
  10. Pulse output voltage: ≥12KV
  11. Cleaning time before draught fan: 1S±0.5S
  12. Cleaning time after draught fan: 10S±1S
  13. Temperature regulation range: 32℃~55℃
  14. Temperature display error: ±1.0℃
  15. Electronic regulation error: -7%~+7%
  16. Constant temperature characteristics:
      1. Heating time or temperature-adjusting time: ≤15S; overshooting temperature: ≤2℃
      2. Anti-jamming overshooting temperature: ≤3.5℃; stable time: ≤15S
      3. Accuracy of water temperature: ±1.0℃
      4. Temperature rise when water if off: ≤6℃

V. Debugging method
1. Display of rated quantity of hot water (Q)
When the state is switched from ON to OFF and the ON/OFF button is held for over 2sec, X value will be displayed on the digital display tube of preset temperature (press the ON/OFF button to cancel the display of X value). Relation between X value and Q is:
X
Q = ——
4 Q: Rated quantity of hot water (L/min); X: Display value of digital tube (hot water quantity can be as accurate as 0.25L/min).
The maximum thermal load of water heaters is determined indirectly by water yield. Considering the possible errors with thermal efficiency of the water heater or the control system itself, accuracy of hot water yield can be ensured through adjustment of X value before delivery of water heaters. For example:
Set the water heater to HH state and the maximum water yield can be converted after the water heater runs stably. For example, the hot water yield of a 10L (theoretically, X=40) water heater within an acceptable range of thermal load is 10L/min, but the measured maximum hot water yield during production is 10.25L/min, 0.25L/min higher than the predetermined value; therefore the X value can be changed to 39 by turning corresponding knob on the controller. On the contrary, if the measured maximum hot water yield during production is 9.75L/min, 0.25L/min lower than the predetermined value, the X value can be changed to 41 by turning corresponding knob on the controller.
Range of X value: 28-91 (i.e. 7L-22L), and each change by 1 to X value will cause a change of 0.25L/min to Q.

小火调节旋钮:Small fire adjustment knob
X值调节旋钮:X value adjustment knob
2. High volume operation
Where a higher water volume is needed, larger than normal volume, as during inspection or on special occasions, the high volume program can be activated:
When the state is switched from OFF to ON and the ON/OFF button is held for over 2sec, the buzzer will make two long “Dee” sound and then the system will enter high volume state. Press ON/OFF button and shut down the machine to exit high volume state.
3. HH operation
HH program can be activated in order to perform inspection over maximum thermal load, smoke index and electronic regulation etc:
Press and hole Up and Down keys for over 1.5sec, the preset temperature is set in “HH” state to enter HH program. Press any key to exit HH state.
4. The aperture of burner nozzles should be enlarged to 1.2 times that of the originally rated hot water yield during installation.

VI. Performance features
1. Process of water change
Water flow can be automatically adjusted during operation: When the water heater is turned on, the control system will shall automatically adjust the water volume to a proper value as indicated in following curve; under special circumstances, however, the control system will automatically increase water flow to reduce discharge temperature to preset value if the discharge temperature cannot fall to the preset temperature due to temperature rise of cold water in summer; on the contrary, the control system will automatically reduce water flow to increase discharge temperature to preset value if the discharge temperature cannot rise to the preset temperature due to temperature drop of hot water in winter. Therefore, users do not have to adjust the water volume, and the system can automatically ensure proper discharge temperature both in summer and in winter.

Note: Q is the rated hot water yield of the water heater; this water volume curve is measured where the pressure of input water is sufficient to overcome water flow resistance of the water heater.

2. Gas pressure change
In normal use, when gas pressure varies within the rated range of -40%~+100%, constant-temperature characteristics of the water heater will not be affected; when working under maximum thermal load, the control system can control the gas flow by detecting the maximum hot water produced by the water heater to stabilize the maximum hot water yield as much as possible, which can prevent increase in maximum hot water yield as a result of increase in gas pressure and decrease in maximum hot water yield as a result of decrease in gas pressure, and this is the electronic regulation function of the control system.
VII. Configuration


Name

Model

Quantity

Remarks

Main controller

DMD-01QH2
DMD-01FH2
DMD-01QD
DMD-01FD

1

DMD-01QH2: Ordinary two-speed fan
DMD-01FH2: Staged two-speed fan
DMD-01QD: Ordinary DC fan
DMD-01FD: Staged DC fan

Display

DMD-02

1

The display can be customized

Rotor gas governor solenoid valve

QTZ-A-×

1

A: 7~16L
X: Gas type(T: Natural gas Y: LPG R: Manufactured gas)

Temperature sensor of water inlet and outlet

 

1 for each type

NTC parameters: R25℃=100K B25/50℃=3950K

Connecting wire

 

1 set

 

Electric water valve

DHLF-A

1

 

Water valve joint

 

1

G1/2

External joint of gas valve

 

2

G1/2 or G3/4

Model and functions of main controller:
DMD-01QH2: Ordinary AC fan control,driving AC220V two-speed fan.
DMD-01FH2: Ordinary AC fan control,staged combustion, driving AC220V two-speed fan.
DMD-01QD: Ordinary DC fan control, driving DC24V DC fan.
DMD-01FD: Ordinary DC fan control, staged combustion, driving DC24V DC fan.
5R added to the end of the model shall indicate that the gas governor valve is 5R manual gas valve.
Since perfect performance of the control system is based on rational coordination with the whole machine, it is recommended that users perform complete functional test during selection of control system to ensure the best application effect, especially test of environmental suitability. Take LPG AC fan as an example:
Under conditions of: temperature of inlet water: 5~30℃; working voltage: AC160~260V; water pressure: 0.02~0.7Mpa; gas pressure: 1600~4500Pa; temperature of outlet water: 32~55℃, if the environmental suitability is tested under the most unfavorable conditions, i.e. with a working voltage of AC160V or AC260V and a gas pressure of 1600Pa or 4500Pa, and the water heater still can work stably under the minimum thermal load without stalling, staged combustion control can be saved, or staged combustion control should be applied.

VIII. Precautions

  1. Thermal radiation protection measures should be taken during installation of the control system, and it is recommended that the control system is separated by iron plates from burners.
  2. During installation of ignition needle, the discharge distance should be 4-5mm.
  3. The control system must be reliably earthed.
  4. The control system should be protected from rain and sun exposure.
  5. The control system should be protected from strenuous vibration and impact during operation.
  6. When debugging is completed, shut down the system (turn off water supply or shut down the machine) first and then disconnect power supply.

IX. Exhibits

    1. See Fig. 1 for functions of control panel (for reference only, shape and appearance can be customized);
    2. See Fig. 2 for the sketch-map of controller appearance;
    3. See Fig. 3 for the installation dimensions of controller;
    4. See Fig. 4 for the reference chart of technical requirements of installation structure of temperature sensor;
    5. See Fig. 5 for work flow chart;
    6. See Fig. 6 for installation dimensions of solenoid valve;
    7. See Fig. 7 for wiring chart of the system;
    8. See Fig. 8 for installation dimensions of electric water valve;
    9. See Fig. 9 for installation dimensions of various joints;
    10. See Fig. 10 for reference installation chart.

 

 

开/关:ON/OFF
客户商标:Customer trademark
设置温度:Set temperature
故障代码:Error code
Fig. 1 (Panel function chart)

 

Fig. 2 (Sketch-map of controller appearance)
 

Fig. 3 (Chart of installation dimensions of controller)

 

Fig. 4A: (Method 1 for installation of input and output water temperature sensor)
传感头:Sensing head
水管:Water tube
保证传感器至水管壁间隙不小于2mm:Gap between the sensor and the water tube wall should be no smaller than 2mm
O形密封圈(径向密封):O gasket ring (radial seal)
此处孔径不小于:Aperture here no less than
输出线:Output line
 

Fig. 4B: (Method 2 for installation of input and output water temperature sensor)

传感头:Sensing head
水管:Water tube
保证传感器至水管壁间隙不小于2mm:Gap between the sensor and the water tube wall should be no smaller than 2mm
O形密封圈(径向密封):O gasket ring (radial seal)
此处孔径不小于:Aperture here no less than
输出线:Output line

Notes:

    1. Radial seal: Make sure dimensions of the gasket ring are coordinated for sealing purpose, and the sealing effect is not realized by radial deformation under the axial compression from the gasket ring under axial forces.
    2. The sensing head should be well positioned, without direct contact with the water tube wall from any direction.
    3. The sensor should be protected against strong impact.
    4. The outlet water temperature sensor should be installed near the uppermost water outlet of the heat exchanger.

Fig. 4(Sketch-map for installation and technical requirement of temperature sensor)


 

接通电源,CPU上电复位,数码管闪动预置温度3次,然后显示实际温度:Connect power supply, CPU power on reset, digital tube flashes the preset temperature 3 times and then display the actual temperature
断电:Disconnect power supply
检测气阀是否开路:Check whether or not the gas valve is open-circuited
是:Yes
开关阀开路显示错误代码“E3”; 调节阀开路显示错误代码“E4”: Error code “E3” will be displayed for open-circuit of switch valve; Error code “E4” will be displayed for open-circuit of governor valve
报警:Warning
检测温度传感器是否开路,短路:Check whether or not the temperature sensor is open-circuited or short-circuited
是:Yes
显示错误代码“E6”:Display error code “E6”
关闭水挚开关关闭系统:Shutdown the water switch and the system
进入待机状态:Entering standby state
关闭水挚开关关闭系统:Shutdown the water switch and the system
打开水挚开关,启动系统:Turn on the water switch and the system
气阀安全关闭,10秒后风机停止:Safe shutdown of gas valve and the fan ceases to work 10sec later
自动调整水量为正常值:Water volume automatically adjusted to proper value
气阀安全关闭,10秒后风机停止:Safe shutdown of gas valve and the fan ceases to work 10sec later
风机工作: Fan starts to work
1秒后:1sec later
风压开关是否接通:Whether or not the air pressure switch is turned on
否(7秒后):No (7sec later)
显示错误代码“E7”:Display error code “E7”
是:Yes
脉冲点火气阀打开:Impulse ignition gas valve opened
否:No
是:Yes
是否有火焰:Flame
否:No
安全时间(3秒+3秒)是否到达:Safety time (3s+3s) reached
是:Yes
是:Yes
定时时间(20分)是否到达:Set time (20min) reached
否:No
燃烧器正常燃烧,风机正常工作:Combustor and fan work normally
显示错误代码“E1”:Display error code “E1”
数秒后:Several seconds later
温度是否达到预置温度:Temperature comes to present value
否:No
水量自动增大或减少:Automatic increase or decrease of water volume
是:Yes
检测温度传感器是否超温(75℃):Temperature sensor over temperature (75℃)
是:Yes
显示错误代码“E5”:Display error code “E5”
否:No
风压开关是否开路:Air pressure switch open-circuited or not
是(5秒后):Yes (5sec later)
显示错误代码“E7”:Display error code “E7”
否:No
是:Yes
是否有火焰:Flame
否:No
显示错误代码“E2”:Display error code “E2”

Fig. 5 (Work flow chart)

Model instructions:
E.g.: QTZ—A--T
Gas type Natural gas
Applicable rated hot water yield A: 7-16L, B: 16-32L
Valve type Rotor gas governor valve

Model and specifications

Model

Applicable to

Minimum flow

Maximum flow

Model

Applicable to

Minimum flow

Maximum flow

QTZ-A-Y

7-16L

m2/h

m2/h

 

 

 

 

QTZ-A-T

7-16L

m2/h

m2/h

 

 

 

 

QTZ-A-XR
(X: to be determined by type of manufactured gas)

7-16L

m2/h

m2/h

 

 

 

 

 

 

 

 

Notes:

  1. The test shall refer to the current parameter of the electric test station (size);
  2. Repeat three times, and the minimum relative error of flow shall be less than 10%;
  3. Pay attention of error of gag flow measuring apparatuses in dry air;
  4. Manufactured gas is not indicated due to complicity.

Performance indexes

Items

Parameters

Remarks

Air tightness

External leakage

<0.03L/h

4.2Kpa
Dry air

Internal leakage

<0.03L/h

Insulation resistance

>100MΩ

DC 500V

Service lift

≥3*106 times

Repeated open and close

Fig. 6 (Installation and performance chart of solenoid valve)

 

 

探火线:Fire detecting line
打火线1:Ignition line 1
打火线2:Ignition line 2
主控器:Main controller
接地线:Earthing line
DC12或DC16V分段阀:DC12V or DC 16V sectional valve
接电控阀电机线:Connected to motor line of electric valve
接电控阀信号线:Connected to signal line of electric valve
接AC220V电源:Connected to AC220V power supply
进水温度传感器(100K):Input water temperature sensor (100k)
公共(白色线):Public (white line)
高速(红色线):High speed (red line)
接高低速风机:Connected to high-and low-speed fan
出水温度传感器(100K):Output water temperature sensor (100k)
低速(蓝色线):Low speed (blue line)
风压开关:Air pressure switch
接调节阀:Connected to governor valve
接开关阀:Connected to switch valve
显示器:Display
开/关:ON/OFF
温控器:Temperature controller

Fig. 7A (Wiring chart of AC fan system)

 

AC200V 电源输入:AC200V power input
红红:Red and red
Φ4.2 地环:Φ4.2 ground ring
黑:Black
调速电压:Variable-speed voltage
温度信号:Temperature signal
探火线:Fire detecting line
打火线1:Ignition line 1
打火线2:Ignition line 2
主控器:Main controller
接地线:Earthing line
DC12或DC16V分段阀:DC12V or DC 16V sectional valve
接电控阀电机线:Connected to motor line of electric valve
接电控阀信号线:Connected to signal line of electric valve
接AC220V电源:Connected to AC220V power supply
进水温度传感器(100K):Input water temperature sensor (100k)
公共(白色线):Public (white line)
高速(红色线):High speed (red line)
接高低速风机:Connected to high-and low-speed fan
出水温度传感器(100K):Output water temperature sensor (100k)
低速(蓝色线):Low speed (blue line)
风压开关:Air pressure switch
接调节阀:Connected to governor valve
接开关阀:Connected to switch valve
显示器:Display
开/关:ON/OFF
温控器:Temperature controller

Fig. 7B (Wiring chart of DC fan system)

出水口: Water outlet
进水口:Water inlet
接G1/2接头:Connected to G1/2 joint
信号插件:Signal plug-in
电机信号输入:Motor signal input

Product model: DHLF-A

No.

Items

Enterprise index

1

Applicable water pressure

≤0.5Mpa

2

Discharge pressure

0.8-0.9Mpa

3

Pressure withstanding

1.2Mpa

4

Flow range

4-20L/Min

Remarks

Maximum measured flow with an input pressure of 0.1Mpa and without resistance at outlet is ≥20L/min.

Fig. 8 (Chart of installation dimensions of electric water valve)

3/4气阀进气接头:3/4 gas valve inlet joint
1/2气阀进气接头:1/2 gas valve inlet joint
1/2 水阀进水接头:1/2 water valve inlet joint
说明:
  1. 以上接头均配O型密封圈20*2.65GB/T3452.1-1992

Notes:
1. All joints mentioned above are equipped with O gasket rings 20*2.65GB/T3452.1-1992
图9 热水器各接头安装尺寸图
Fig. 9 Chart of installation dimensions of each joint of water heater


出水温度传感器安装位置尽量靠近吸热翘片出口:The output water temperature sensor should be positioned as close as to the output of absorber flake.
进气管:Gas feed tube
进水温度传感器:Input water temperature sensor
电控水阀:Electric water valve
水信号线:Water signal line
电机控制线:Motor control line
出水口:Water outlet
燃气入口: Gas inlet
进水口:Water inlet
Fig. 10 (Reference installation chart)



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