Herz H7990-08 Series Manual

items: working states (cool, heat or ventilation), the speed of fan coil, room

temperature,

set-point.

There

are

following

keys on

the

panel: On/Off “ ”, Exchange

mode (cool, heat or

ventilation) “ ”, Select fan speed (high, medium, low or auto) “ ”,

set-

point temperature “

” and “”.

H7990 adopt digital control technology with large LCD display, It shows the

following

BASIC FEATURES STATUS DISPLAY



Room temperature setting



Manual or Auto 3-speed changeover



Defrost (low temperature protection)



IR remote control (Option)



Blue Backlight (Option)



Working Status: Cool , Heat

, Ventilation



Fan Speeds: Low

, Medium

, High





and Auto.
Room temperature display
Temperature setting display

SPECIFICATIONS



Sensing element: NTC



Accuracy : ± 1℃



Set-point range: 5℃ to 35℃



Display range: 0～50℃



Operation environment: 0～45℃



Operating Humidity: 5～90%RH (non-condensing)



Power supply: AC 85～260V, 50/60Hz



Switch current rating: Resistive: 2A, Inductive: 1A



Rated Power:  2 W



Wirings: Screw-in terminals, each terminal capable of

accepting 2 x 1.5 mm2 or 1 x 2.5 mm2 wires



Housing: ABS + PC Flame Retardant



Dimensions: 86 × 86 × 13 mm ( W × H × D )



Hole pitch: 60 mm ( Standard )



Protection Class: IP30



Display: LCD

OPERATION

 On/Off: Press “ ” to turn on, press “ ” again to turn off thermostat and its output.
 Setting temperature: Press

“” to reduce set-point, press “” to raise set-point, and 0.5℃ changed once.

 Mode Selection: Press “ ” to change system working in cooling “ ”, heating “ ” or ventilation “ ” mode, the related

icon will flash, and it will be confirmed automatically after 5 seconds. The ventilation function is invalid for H7990 08.

 Fan Speed Selection H7990 08

:Press “ ” to change fan speed among “ (Hi)”, “ (Med)”, “ (Low)”

or “Auto”.

Under

auto fan speed “Auto”, the fan-speed will be changed automatically. Auto LOW-speed When the difference

MODEL DENOMINATIONS

H7990 08 –

R: IR remote function. Blank is invalid. (Remote controller should be ordered additionally)
L: Backlight available. Blank is invalid.

Y: Control damper to open or close.
DA/DA2: Control Motorized Valve (DA: Control 2-wire N.C. FCU valve; DA2: Control 3-wire FCU valve) and 3-speed

fan; When the temperature reaches the set-point, it will close the Motorized Valve with the fan still running.

DB/DB2: Control Motorized Valve (DB: Control 2-wire N.C. FCU valve; DB2: Control 3-wire FCU valve) and 3-speed

fan; When the temperature reaches the set-point, it will close the Motorized Valve and Fan both.

FCV2: Control 4 pipe fan coil units, Control two Motorized Valves and 3-speed fan, when the temperature reaches

the set-point, it will close the Motorized Valves with the fan still running.

Data sheet for H7990 08, Issue 0916

HERZ Armaturen Gws.m.b.H
Richard-Strauss-Strasse 22,1230 Vienna, Austria.

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HERZ H7990-08 Series Thermostat

H7990 Series thermostats are available for individual room temperature control

in residential, industrial and business premises. Suitable for 2-pipe or 4-pipe Fan Coil
configuration.

between room-temperature and set-point exceed 1℃, Auto MED-speed When exceed 2℃

, Auto HI-speed When exceed 3℃.

 Control Damper (H7990 Y): The damper will be

open when (1) room temperature is higher than set-point in cooling;(2)

room temperature is lower than set-point in heating, Otherwise the damper will be closed.

 Control Motorized Valve under 2-pipe configuration (H7990 08 DA/DB/DA2/DB2): If the

difference between room
temperature and set-point exceed 1℃, FCU valve will be open; if room temperature and set-point are equal, H7990 08 DA/DA2
will close the FCU valve with the fan still running, H7990 08 DB/DB2 will close the FCU valve and Fan both.

 Control FCU Valve under 4-pipe configuration (H7990 08 FCV2): In cooling, when the room temperature is higher than
set-point, the cooling Valve will be opened. Otherwise it will be closed. Heating valve is always closed. In heating, When the
room temperature is lower than set-point, the heating valve will be opened. Otherwise it will be closed. Cooling valve is always
closed.

DEF

ROST (LOW TEMPERATURE PROTECTION)

 Description: when the thermostat turns off and the room temperature is lower than 5˚c, it will be turned on
automatically in heating mode with “ ” showing, under H7990 08 DA/DB/DA2/DB2/FCV2 models, the system will be in heat
mode and fan runs in high speed. Under H7990 08 Y model, the motorized damper will be open. The thermostat will turn off
when room temperature is higher than 7˚c

 Set low temperature protection: Turn off the thermostat, press “ ” and “” buttons simultaneously and hold for 3
seconds, it will display “00” or “01”, press “” or “” key to adjust. “00” indicates low temperature protection invalid, “01”
indicates low temperature protection function valid. The default is “00”.

WIRING DIAGRAMS

MOUNTING

1. Open the main control
panel: put the screwdriver
(3.5mm) into the block
4mm along the bevel.
Prize up, open the clips.

2. Take off the wires. 3. As per wiring diagram,
connect it with terminals,
fixed by the screwdriver.

4. Put the connected
thermostat onto the back
panel in the wall, then fix it
with the two screws in the
packing box.

5. Put the cover with 30
degree angle, then fix the
up two clips.

6. Push the places of the
two down clips, fix the
cover, and finish the
installation.

H7990 08 DA/DB

L

N

Val

Med

Low

Fan

Valve

AC85～260V 50/60Hz

N L

Hi

H7990 08Y

N

L

Damper

VC
VO

AC85～260V 50/60Hz

N L

H7990 08 DA2/DB2

L

N

VO

Med

Low

Fan

Valve

VC

AC85～260V 50/60Hz

N L

Hi

H7990 08 FCV2

L

Cooling

N

Med

Low

Fan

Val 1

Val 2

Heating

AC85～260V 50/60Hz

N L

Hi

HERZ Armaturen Gws.m.b.H
Richard-Strauss-Strasse 22,1230 Vienna, Austria.

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