Ventilation - Optima Controller

Ventilation - Optima Controller

Genvex Optima Controller


This page describes the Genvex Optima 300 Controller. 

Please remember that the ventilation system will work perfectly well in the state it is set up when the unit is commissioned by the installers, but there are features and facilities available that can make your life easier.

Besides, if you are like me, you will always want to know how something works, and get the very best from it.


Using the Genvex Optima 300 Controller

You may scroll through this section, to locate the following sub-sections:

  • Mounting the Genvex Optima 300 Controller
  • Genvex Optima 300 Controller Key Pads
  • Main Menu - Options
  • Main Menu - Date and time
  • Main Menu - Calendar
  • Main Menu - User menu
  • Main Menu - Display
  • Main Menu - Info operation
  • Main Menu - Service menu
  • Recommended and our system parameters
  • Want to know more?

Once you have viewed this page, please also view the related pages:

Mounting the Genvex Optima 300 Controller

The Genvex Optima 300 controller is 110mm x 110mm square and 30mm deep. It is mounted on a wall to allow the on-board thermostat, light sensor and proximity detector to operate. The installation instructions warn about keeping the controller mounted away from heat and light sources, and this is very important.

Underneath the bottom of the controller is an SD card on which is recorded performance data on the operation of the system. Next to the SD Card is a micro-USB socket from which you can connect the controller to your computer.

The SD card can be removed and replaced; and a standard micro USB cable can be connected to the Genvex Optima 300 controller while it is switched on and attached to the wall.

Connection of a computer to the USB socket allows you to easily program the Genvex Optima 300 controller; however, you are supplied with a very comprehensive manual that allows you to perform the same programming functions by using the 7 Keys on the controller.

Genvex Optima 300 Controller Key Pads

Genvex Optima Controller

The Genvex Optima 300 controller has 7 key pads which are used to set the current mode and to perform programming functions.

These key pads are hardly noticeable and initially I had a tendency to press the LCD display in error.

You will find that the most useful keypad is K6 which displays the temperatures of the sensors and the fan speeds.

K2 is also very useful to give the system a one-hour boost when having a shower or bath.



K1 - Fan speed

The unit has four fan speeds of which the lower 3 are programmable and the 4th is 100%. Each press of K1 steps upwards through the speeds, and after 100%, it reverts

to the lowest speed. Prolonged depression of the key turns off the fans and this is useful if neighbours are having bonfires. This facility is very useful especially since you can easily program the fan speeds to what you want (the defaults are 40%, 70%, 100% and the fixed 100%).

K2 - Extended operation

This button makes the setting of fan speeds 3 and 4 using K1 permanent, or temporary for x hours, where x can be changed in the service menu. You may want to use the temporary feature to boost the fan speed during extended cooking or bathing periods.

K3 - Heat pump

The heat pump can be used to heat your property in winter or cool it in the summer. When a "-" is showing, the heat pump is disabled; when a '+' is showing, the heat pump will operate provided the room temperature is outside the thermostat setting parameters. Don't be afraid to use the heat pump as it only uses 250W and provides useful heating or cooling.

K4 - Main menu

The main menu lets you set the date, programmable calendar operations, and gives access to the User Menu, the Information Menu and the Service Menu.

K5 - Filter change

The ventilation unit uses filters and it is wise to keep a spare set in stock. The filter life can be programmed for up to 6 months, and when that time has expired, the filter warning light comes on to remind you to change the filters.

K6 - Information menu

This is perhaps the most useful menu of the whole unit. It shows the temperature of up to 9 points, including the air coming in from outside, the air exhausted to the outside, the extracted air from the rooms and the supply air to the rooms. You can also see the fan speeds (they may be over-ridden when necessary) and the status of various alarm settings.

K7 - Thermostat temperature

This button is used to set the thermostat temperature which can determine whether or not the heat pump cuts in to provide either heating or cooling. Don't forget to press enter afterwards, else your new setting will not be accepted. 20C is a good choice of temperature here.

For a comprehensive review of the Genvex Optima 300 Controller, click here.

For a comprehensive review of the Genvex data logging software, click here.

Main Menu - Options

The main menu lets you select one of these options:

  • Main Menu - Date and Time
  • Main Menu - Calendar
  • Main Menu - User Menu
  • Main Menu - Display
  • Main Menu - Info operation
  • Main Menu - Service menu

We will explore what each of these options are in the sections below.

Main Menu - Date and Time

This menu allows you to set the date and time of the system. The following settings are available:

  • Hours (0 to 24)
  • Minutes (0 to 59)
  • Weekday (1 to 7, with 1 being Monday)
  • Date (1 to 31)
  • Month (1 to 12, with 1 being January)
  • Year

Once the date and time is set, it can be left, although you will need to manually advance and retard the "hours" by one hour when daylight saving time changes.

Main Menu - Calendar

This is a very useful feature of the Genvex Controller.

  • It allows you to set up to 10 different timed combinations of fan speed and temperature offset for each of the seven days of the week.
  • It allows you to very easily switch programmable times on (using these options) and off (using manual control).
  • There is a "copy day" function, that allows you to set the: time, fan speed and and temperature offset for one day, and very easily copy it to another day.

Remember that you can change the default fan speeds to whatever you prefer, though the default values are usually ideal.

The "temperature offset" is used to adjust the target room temperature. You may want to turn down the thermostat at night by say 3C to stop the heat pump maintaining the same room temperature. To do this, you would set the "temperature offset" to -3.

Main Menu - User Menu

The user menu is the only menu that most users will go to, and it allows the following changes.

01 - Required Temperature

The required temperature can be set anywhere between 10C and 30C, and the default is reasonable at 20C. Although the room thermostat sensor in the Genvex Optima Controller is the normal means of controlling temperature, you can use the sensor in the air supply or the air extract. To change the sensor selection, you need to use the Service Menu. I use 20C and the room thermostat sensor.

02 - Cooling Offset

Once the heat pump heats your property to the required temperature and above, it can then go into cooling mode and waste power trying to cool the property, even during winter. The cooling offset can be set between 3C and 10C and the default is 5C (not 52C as is in the manual). Using the default of 5C, the Required Temperature will need to rise to 25C before cooling starts.

03 - After-heat (Cooling ON/OFF)

The Genvex Controller lets you disable cooling by setting this option in the OFF position. It would be a good idea to keep this setting in the OFF position in winter to prevent cooling inadvertently starting or if it is not required. There are a number of different parameters that need to be correctly set for the heat pump to turn on and the cooling to operate.

04 - Timer Levels 3 and 4

Normally the fans in the main ventilation box will be operating at fan speed 1, or more usually 2. However, you may need to temporarily boost the ventilation. When this setting is set 'OFF', setting the fan speed to 3 will maintain that speed indefinitely (unless program control reduces it). If however, you set this to 'ON', the fan speed will automatically revert to speed 2 after the number of hours in setting 17 in the service menu.

05 - Change Filter

A built in timer counts how many months the unit has been operating for. You can set here the number of months between 1 and 6 when the change filter change warning light comes on.

Main Menu - Display

You will probably never need to change any of these options once you have set them initially. What I will do however is first list the options and then pass on some practical comments on which specific settings are best. The display options available are:

  1. Display Language - Danish, English, German or French
  2. Program Information - Hardware and software codes
  3. Screen Saver - select brightness and what is displayed in dormant mode
  4. Pause Time - time before the screen saver kicks in
  5. Auto Wake Up - Enable/disable proximity sensor
  6. Auto Lightness - set sensitivity
  7. Lightness Day - set maximum brightness during the day
  8. Lightness Night - set minimum brightness in darkness
  9. Lightness Day Screen saver - set maximum brightness during the day
  10. Lightness Night Screen saver - set minimum brightness in darkness
  11. Default Reset - reset system to one of two conditions (caution)
  12. Safety Menu - use to set passwords
  13. Date and Time Menu - if 'ON', need password to access menu
  14. Calendar Menu- if 'ON' need password to access menu
  15. User Menu - if 'ON' need password to access menu
  16. Display - if 'ON' need password to access menu
  17. Service Menu - if 'ON' need password to access menu
  18. Password - enter password for options 13 to 18

I have not used any passwords or security in our configuration; if you have young children, they should be told that playing with the unit is forbidden.

All settings in ours are as per the default settings although I have disabled the screen saver in option 3.

Performing a reset of any kind could be particularly annoying if done accidentally.

Also, changing some parameters in the Service Menu could cause damage is done by young fingers.

Main Menu - Info Operation

The Info Menu is the most useful menu as it displays the key temperatures, air movement and relay status. The combination of temperature settings give a clear status on the efficiency of the heat exchanger and the effectiveness of the heat pump in both heating and cooling modes. This menu provides information and gives no facility to perform any updates:

Temperature display

The temperature sensors are labeled T1 to T9

  • T1 Supply Air - air leaving the unit going to the rooms
  • T2 Room - room thermostat
  • T3 Fresh air - air brought in from outside entering the unit
  • T4 Exhaust air - stale air output from heat exchange going out
  • T5 Pre-cool surface - I don't really understand this
  • T6 Cool Surface - I don't really understand this
  • T7 Air extraction - air entering unit after being extracted from rooms
  • T8 Water Frost - if not fitted, shows -30
  • T9 Help sensors - if not fitted, shows -30
Fan speeds and valves

Pressing the down arrow from the temperature display gives the fan speeds and valve operation. However, and particularly when the heat pump is operating in cooling mode, the microprocessor often over-rides your set fan speeds and particularly increases the extract air to keep the compressor cool and this will produce more noise in rooms where air is extracted. Items displayed are:

  • Supply air in % - % of the maximum fan speed
  • Extract air in % - % of the maximum fan speed
  • Bypass valve in %
  • Water valve in %
Relay Status

Pressing the down key once again shows the status of the relays in the unit.

  • R1 - Compressor - The compressor is used for heating or cooling.
  • R2 - Electrical after-heat
  • R3 - Electrical pre-heat
  • R4 - Defrosting
  • R5 - Heat Level 2 (R10)
  • R6 - Heat Level 3 (R11)
  • R7 - Heat Level 4 (R12)
  • R8 - Cooling system
  • R9 - Help function
Error messages

Error conditions are indicated when the status is shown as "on"; the following status are shown:

  • Control System Stopped - caused by various fail safe errors
  • Change Filter -
  • Pressure Switch - caused by excessive pressure in system.
  • Frost
  • Communications Error
Duration of operation

Finally, the controlled keeps a log of the duration of various statuses in hours and these are below:

  • Total time of operation
  • Level 0 fan speed
  • Level 1 fan speed
  • Level 2 fan speed
  • Level 3 fan speed
  • Level 4 fan speed
  • Relay 1 operation
  • Relay 2 operation
  • Relay 3 operation
  • Relay 4 operation
  • Relay 5 operation
  • Relay 6 operation
  • Relay 7 operation
  • Relay 8 operation
  • Relay 9 operation

As we can see above, the system provides some very useful information on temperature as it shows how little the heat loss is (when comparing fresh air to exhaust air or supplied air to extracted air).

There are also some interesting and diagnostic parameters available.

I really only view the temperature display on the first screen of the information menu.

Main Menu - Service Menu

The user menu allows you to change the most useful features of the system, however the service menu gives you much additional flexibility.

If you choose to have one of these systems installed, do consider having a slightly higher powered system than is recommended. This is what I did, and the benefits for little additional capital cost are: better heat pump heating in the winter, and much improved cooling in the summer.

The service menu parameters are numbered 10 through to 40 and we will go through each:

10 - Level 1 supply air

This is the level 1 supply air and is usually used when nobody is at home. The default setting is 40%, but I have set mine to 25% because I have an oversized unit and also because I didn't want the heat pump to kick in at this lowest level. The minimum supply air for the heat pump to operate is set by parameter 24, and is a default 30%.

11 - Level 2 supply air

The default level here is 70%, but I have set ours to 40% and this allows the heat pump to operate.

12 - Level 3 supply air

The default level here is 100%, and to me this is a waste as 100% is fixed at level 4. Therefore, I have set this to 65%, and when using the heat pump for cooling in the summer, I operate at level 3.

13 - Level 1 extract air

The default level here is 35%, but I have set ours to 25%.

14 - Level 2 extract air

The default level here is 55%, but I have set ours to 40% and this allows the heat pump to operate. Note how the default supply setting is always slightly less than the supply setting; the reason for this is that it is good to maintain a small positive air pressure inside the house, and so when the system is running all doors and windows should be kept closed.

It is interesting that the Info Menu shows that the 40% is reduced to 38%.

15 - Level 3 extract air

The default level here is 70%, yet the default supply is 100%, very strange; but I have set ours to 65%. in practice, when the heat pump is running in summer in cooling mode, the 65% setting here is over-ridden and it varies and the value and can go to 100% to keep the compressor cool.

16 - Fine tuning (T2)

it is possible to adjust the displayed room temperature by between 0C and -5C, with the default being -3C. Mine is set to -5C, and I do not believe this parameter works at all as changing it has no effect on anything.

17 - Timer levels 3 and 4 delay

Levels 3 and 4 can be programmed to automatically revert back to level 2 after a specified number of hours. This parameter holds the number of hours that levels 3 or 4 would be maintained at. The default period is 3 hours and ours is set at 1 hour. You may want to use this facility to increase the fan speed while having a shower or bath since you would not have any windows open and nor would you have a wasteful extractor fan running.

18 - Filter Stop

If you set this to 'ON', you will get a warning when the filters are due to be changed, and 14 days later the whole unit will shut down. The default setting is 'OFF' and ours is set 'OFF'.

Our system was installed in December 2009, and they can get very dirty. After I get the 6-month alarm, I vacuum each of the filters carefully and then change them after a further 3 months.

19 - Method of Temperature Control

This setting allows the target temperature to be determined by one of the three temperature sensors.

  • Use mode '0' for room control
  • Use mode '1' for supply air control
  • Use mode '2' for extracted air control

Mode '0' is the default setting and it is what ours is set at though I did have an extended debate with the installation engineer on the best setting.

20 - Pre-heat ON

If there is a pre-heater in the fresh air supply, this parameter must be set 'ON' for it to operate. As we are in a warmer part of southern England, we did not purchase this option. The default is 'OFF', and that is the setting in our unit.

21 - Pre-heat Temperature

If you are optionally using the pre-heater, you can set the temperature at which the pre-heating starts between -15C and 0C. The default is -10C, and that is what our setting remains at.

22 - Regulation Water

If a water after-heat surface is fitted, the regulation time can be adjusted between 1 and 250 seconds with a default of 20 seconds. We do not have one of these fitted and I don't fully understand this and so the value remains with the default 20 seconds.

23 - Regulation Electricity

If an electrical after-heat surface is fitted, the regulation time can be adjusted between 1 and 30 minutes with a default of 3 minutes. We do not have one of these fitted and I don't fully understand this and so the value remains with the default 3 minutes.

24 - Minimum Air Volume

The heat pump is designed with a minimum air volume, and if the air volume does not reach this minimum value, the heat pump is turned off. The default is set to 30%, and it should never be less than this else the compressor will turn off. I have set this to 32%, but since my Level 1 supply is 25% and Level 2 supply is 40%, we will never have the compressor on with an air volume of less that 40%.

25 - Water Frost

If a water after-heat surface is fitted, this parameter can be set on to use it. If no water after-heat surface is fitted, this setting must be set to 'OFF'. We do not have this feature and it is set 'OFF'.

26 - Water Frost Temperature

If a water after-heat surface is fitted, this parameter sets the temperature when the value is opened to allow the flow of hot water. The temperature can be set between 0C and 10C with a default of 5C. We do not have this feature and it is set to 5C.

27 - Help Functions

This parameter can be set to one of six values and it is used to integrate your Genvex system with an additional earth heat-exchanger or with additional equipment. These are complex options and if you are installing a very complicated ventilation and heat recovery system, I would recommend you talk to the installers about the extra flexibility that this parameter provides you with.

28 - Device stop

You can configure the unit to shut down by holding down key K1 on the Optima Controller provided this parameter is set in the 'ON' position. If the parameter is set 'OFF', you cannot shut down the unit by holding down K1.

The default setting is 'OFF', but we have our setting 'ON'; the reason we have changed the default is that it allows for the easy change of filters when the unit is off and also, it allows us to shutdown the system if there is a particularly smokey bonfire outside.

Note to Genvex, this doesn't work; I switched the unit 'OFF' by depressing K1, but the fans were still running when I attempted to change the filters so I had to switch it off at the main power switch.

29 - Stop defrosting

The default setting is that defrosting stops when the cooling surface reaches 5C. You may need to increase this under special operating conditions. The setting may be configured between 0C and 15C; our setting remains at the default of 5C.

30 - Compressor differential

This parameter sets the temperature difference between stopping and starting the compressor. The difference can be adjusted between 0.1C and 1.0C. The default selling is 0.4C; ours is set at 0.5C.

31 - Constant ON

If this parameter is set to 'OFF' the room temperature will regulate the heat pump irrespective of the outside air temperature. If this parameter is set on, the heat pump will come on if the fresh air temperature is below the setting of parameter 32.

Our setting is 'OFF'; however, in exceptionally cold weather it may be a good idea to have it 'ON' as the fresh air coming into the property could be quite cool.

32 - Constant temperature

This parameter is set in conjunction with parameter 31. The temperature can be set between 0C and 10C; the default is 5C and that is what our setting is.

33 - Reduce volume of fresh air

The user guide seems to suggest that the volume of fresh air can be reduced even though the same volume of air can be taken in. I will need to explore this setting in more detail as the manual supplied is unclear as to how it works.

The default setting is 'OFF' however, I have set it 'ON'. This setting is used in conjunction with parameters 34 and 35.

34 - Fresh air temperature

This parameter sets the fresh air temperature at which the volume of fresh air is reduced; the reduction takes place at or below this temperature. The setting can be between -15C and 0C with a default of -10C; our setting is -3C.

35 - Supply air volume

This setting determines the magnitude of the reduced volume of diffused air (how it does this, I have no idea). The recommendation is to reduce the volume in parameter 11 by 20% (70% recommended to 50%). The default setting if 50% of the original volume (70% reduced to 35%). However, we are set to to reduce the 40% by setting this to 15% to give a reduced volume of 34%.

36 - Restriction on cooling

If your central heating system is running and your property gets rather warm, under certain circumstances, the heat pump could cut in to cool the property while the central heating system is trying to warm it up.

This parameter can be set to prevent this and it can be set between 0C and 20C. We use the default of 15C and what this means is that as long as the fresh air temperature is 15C or under, the heat pump will not cut in to cool the property.

37 - After-heat

If you have an after-heat device fitted (and we have not), if this parameter is set to 'OFF' it will not operate, even if it is required.

38 - Extra electric pre-heat ON

If an electric pre-heat surface is fitted, this must be set 'ON'. If like us you do not have one fitted, then the setting should be 'OFF'.

39 - Extra electric pre-heat temperature

This setting is used to set the air temperature at which it is pre-heated before it enters the unit. The temperature can be set between -15C and 0C; we have retained the default setting of -10C.

40 - Bedroom temperature

If you have an advanced system with valves that can control the air to the bedroom. and a separate temperature sensor there, then you can set a lower temperature for the bedroom. This temperature can be set between 10C and 25C with a default of 10C. Ours is set to 20C, but this has no effect as we do not have this facility

Recommended and our system parameters

As may be seen, there are a vast number of parameters that may be set. The installers will set up your system properly, but you do have the option to fine tune your installation if you would like to.

Required temperature
10 to 30C
3 to 10C
Cooling ON/OFF
Timer levels 3 and 4
Change filter
1 to 6 mon
3 mon
6 mon
Level 1 supply air
0 to 100%
Level 2 supply air
0 to 100%
Level 3 supply air
0 to 100%
Level 1 extract air
0 to 100%
Level 2 extract air
0 to 100%
Level 3 extract air
0 to 100%
Fine tuning (T2)
0 to -5C
Timer levels 3 and 4
1 to 9 hrs
3 hrs
1 hr
Regulation method of temp control
0, 1 or 2
Pre-heat ON
Pre-heat temperature
-15 to 0C
Regulation water
1 to 250 secs
20 secs
20 secs
Regulation electricity
1 to 30 mins
3 mins
3 mins
Minimum air volume
0 to 100%
Water frost
Water frost temperature
0 to 10C
Help functions
Mode 0 to 5
Mode 0
Mode 0
Device stop
Stop defrosting
0 to 15C
Compressor differential
0.1 to 1.0C
Constant ON
Constant temperature
0 to 10C
Reduce volume of fresh air
Fresh air temperature
-15 to 0C
Supply air volume
0 to 100%
Restriction of cooling
0 to 20%
Extra electric pre-heat ON
Extra electric pre-heat
-15 to 0C
10 to 25C


Want to know more?

If you would like to know more about the benefits of installing a ventilation system with a heat pump, please email me on This email address is being protected from spambots. You need JavaScript enabled to view it.. I am willing to offer home visits to see our installation live for a small fee if that would be helpful since I really believe they offer significant benefits.

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