Heat Pump System Overview - Mitsubishi Electric ecodan PUHZ-W50VHA2 User Manual

INTRODUCTION

Heat Pump System Overview

The Ecodan air source heat pump extracts thermal energy from the outside air and transfers this into a property
in the form of hot water as a conventional heating system does.
Due to the outputs available, domestic hot water always takes priority over space heating. The Flow Temperature
Controller 2 (FTC2) targets a preset cylinder target temperature on the TH5 sensor within the cylinder pocket
and communicates with the Ecodan until this temperature is achieved.
A high flow temperature is required in hot water heating to raise the domestic hot water store then the
temperature is reduced in space heating to increase the efficiency. See page 50 for recommended settings and
commissioning procedure.
Mounted in the rear of the Ecodan is an outside temperature compensation sensor. This will modulate the flow
temperature in space heating mode (according to the ambient temperature) to increase the efficiencies of the
system. Due to the lower flow temperatures provided by the Ecodan air source heat pump, radiators need to be
sized in accordance with this, compared to that of conventional boiler systems. In retrofit situations where old
panel type radiators are fitted it may be possible to keep the same physical size of radiator and simply upgrade to
more efficient double panel/double convector type radiators.
Two heating zones can be connected to the Ecodan system in the same way as a conventional heating system.
When the system is installed and commissioned the control equipment will automatically switch between hot
water and heating modes as and when required.
Each of the Ecodan models require sufficient primary flow rate for adequate operation. Due to the large
resistances caused by the plate heat exchanger in the Ecodan, two domestic circulating pumps in series to
produce the required flow rates. These pumps must be set to the same speed or damage to the system may
occur. Pipe diameters will need to increase on the PUHZ-HW140VHA(2) / YHA(2) models to assist in reducing
the resistance, required flow rates are listed on table 1.1 (page 10).
A flow setter valve is supplied with each system to give an indication of the actual flow rate achieved. It should be
installed on the common flow or return pipe work to the Ecodan. Details of this can be found on page 15 of this
manual.
Automatic air vents must be installed at the highest point of the primary system. The slightest amount of air in the
system can reduce efficiencies and even cause the Ecodan to fault.
The primary loop must contain an antifreeze concentration (in accordance with the manufacturers recommended
quantities) to avoid possible freezing during periods when the appliance is not being operated. It is recommended
that a dual inhibitor anti-freeze is used. For information on the Fernox Protectors HP-5c and Alphi-11 see pages
54 and 55 or Sentinel R600 on page 56.
To comply with this requirement the hardness of the mains water should be checked by the installer and if
necessary the optional factory fitted in-line scale inhibitor should be specified at the time of order for hardness.
To optimise running costs it is advisable the homeowners seeks the cheapest possible electricity tariff and that
weather compensation is set up correctly on commissioning. An internet search facility like www.uswitch.com will
be able to help with electricity tariffs.
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