Room Thermostat; Controller Par-W21Maa; Hot Water / Space Heating; Selecting Cylinder Thermostat - Mitsubishi Electric Ecodan PUHZ-W50VHA-BS Homeowner's Manual

Room Thermostat

The aim of the thermostat is to control the room temperature, although one model used will vary from
one home to another its function will not. This is the homeowner's connection to the heat pump boiler.
The room thermostat and the time clock (both supplied by 3rd party manufacturers.) are the 2 main con-
trols for the home owner to use.

Controller PAR-W21MAA

This controller is supplied with the Ecodan® heat pump. Its primary function is as a commissioning tool to
set the target flow temperature. It has a display to show the actual flow temperature and the target tem-
perature. The set-up, displays and modes available are explained later in the manual. Once installed there
are factory settings that will allow the heat pump boiler to start operating immediately, optimising these
temperatures to suit your home will improve running conditions and lower your energy consumption.
These temperatures should be selected during the commissioning stage.

Hot water / space heating

Space heating and hot water heat up cannot be performed at the same time. Hot water will always take
priority over space heating should there be a demand for both; once the tank is heated and up to tem-
perature the unit will change over to the heating of the property. This setting cannot be changed.
Due to lower flow temperature provided by a heat pump boiler additional care must be taken when sizing
the radiators. Ensure that the total heating demand of the property is met by the correct size of heat
pump.
Selecting cylinder thermostats
Care should be taken when selecting a cylinder thermostat. If the thermostat is set higher than the achiev-
able storage temperature of 55°C then space heating will be held off due to hot water priority. It is rec-
ommended that a thermostat on which the maximum temperature can be locked is used. This will prevent
the stat asking for a temperature that cannot be achieved thus preventing space heating from occurring.
(See page 18 for typical heat up times for the hot water tank).

Weather Compensation

The Ecodan® system has a weather compensation mode. This feature is called Eco-heating. This mode
offers varying flow temperatures to the radiators depending on the outside temperature. These tempera-
tures are selected and set by the installer when commissioning the Ecodan® system for further details see
the controller set-up. It is recommended that Eco-heating mode is used for central heating.
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