Mitsubishi Electric ECODAN EHST20 Series Operation Manual page 11

4
Customising Settings for Your Home
Domestic Hot Water (DHW)/legionella Prevention
The domestic hot water and legionella prevention menus control the operation of
DHW tank heat ups.
<DHW mode settings>
1. Highlight the hot water icon and press CONFIRM.
2. Use button F1 to switch between Normal and ECO heating modes.
3. To edit the mode, press down the MENU button for 3 seconds, then select "hot
water".
4. Press F2 key to display the HOTWATER (DHW) SETTING menu.
5. Use F2 and F3 keys to scroll through the menu selecting each component in
turn by pressing CONFIRM. See the table below for description of each setting.
6. Enter the desired number using the function keys and press CONFIRM.
Menu subtitle Function
DHW max. temp. Desired temperature of stored hot water
DHW max. temperature Difference in temperature between DHW max. temp. and the temperature at which DHW mode restarts 5 - 30
drop
DHW max. operation time Max. time allowed for stored water heating DHW mode
DHW mode restriction The time period after DHW mode when space heating has priority over DHW mode temporarily pre-
venting further stored water heating
(Only when DHW max. operation time has passed.)
if you wish to make changes contact installer.
Explanation of DHW operation
• When the DHW tank temperature drops from "DHW max. temp." by more than
the "DHW max. temperature drop" (set by installer), DHW mode operates and
the flow from the primary heating/cooling circuit is diverted to heat the water in
the DHW tank.
• When the temperature of the stored water reaches the 'DHW max. temp.' set by
the installer or if the 'DHW max. operation time' set by the installer is exceeded
DHW mode ceases to operate.
• Whilst DHW mode is in operation primary hot water is not directed to the space
heating/cooling circuit.
• Directly after DHW max. operation time 'DHW mode restriction' will routinely
operate. The duration of this feature is set by the installer and during its opera-
tion, DHW mode can not (normally) be reactivated, allowing time for the system
to deliver primary hot water to the space heating/cooling if required. However,
if at this time there is no current demand for space heating/cooling, the system
will automatically resume DHW mode. This will continue until it receives a de-
mand for space heating.
• After the 'DHW mode restriction' operation the DHW mode can operate again
and DHW tank heating will continue according to system demand.
<Eco mode>
DHW mode can run in either 'Normal' or 'Eco' mode. Normal mode will heat the
water in the DHW tank more quickly using the full power of the heat pump. Eco
mode takes a little longer to heat the water in the DHW tank but the energy used
is reduced. This is because heat pump operation is restricted using signals from
the FTC based on measured DHW tank temperature.
Note: The actual energy saved in Eco mode will vary according to outdoor
ambient temperature.
Return to the DHW/legionella prevention menu.
legionella Prevention Mode settings (lP mode)
1. Use button F3 to choose legionella mode active YES/NO.
2. To edit the legionella function, press down the MENU button for 3 seconds
and select "hot water", then press F4 key.
3. Use F1 and F2 keys to scroll through the menu selecting each subtitle in turn
by pressing CONFIRM. See the table below for description of each setting.
4. Enter the desired number using the function keys and press CONFIRM.
During Legionella Prevention Mode the temperature of the stored water is in-
creased above 60°C to inhibit legionella bacterium growth. It is strongly recom-
mended that this is done at regular intervals. Please check local regulations for
the recommended frequency of heat ups.
Note: When failures occur on the hydrobox, the LP mode may not function
normally.
Menu subtitle Function
Hot water temp. Desired temp of stored hot water
Frequency Time between LP mode DHW tank heat ups
Start time Time when LP mode will begin
Max. operation time Maximum time allowed for LP mode DHW tank heat
Duration of max. temp. The time period after LP mode max. water temp. has been reached
if you wish to make changes contact installer.
Range
40 - 60
30 - 120
30 - 120
DHW tank temp.
Stop
DHW max.
temp.
DHW max.
temp. drop
Start
DHW mode
DHW tank temp.
DHW max.
Stop
temp.
DHW max.
temp. drop
Start
DHW max. DHW mode
operation time restriction
Range
60–70
1–30
0:00–23:00
1–5
1–120
Unit Default value
°C 50
°C 10
min 60
min 30
Restart
Time
DHW mode
Stop
Restart
Time
DHW mode
Unit Default value
°C 65
day 15
- 03:00
hour 3
min 30
10