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Heatpump control functions
SMGB0066 rev.0 - 12/2009
Controller pack
Service Manual
4
note
It is important to minimise this effect as much as possible during installation. The following precautions should
-
be taken
1. Fully insulate the supply and return pipes.
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2. Ensure that the supply temperature sensor is tightly strapped-on to the pipe with the metal clip provided.
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The metal clip should be used directly around the sensor element itself (since it itself improves the heat transfer)
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and then insulation should be placed around the sensor and fixed securely in place.
4.5.4. Heatpump Maximum return High limit
function
•
The Heat Pump itself ensures good control of the outlet water temperature, and switches off the compressor when the
return water temperature gets too high. However, in some circumstances with bi-valent systems, the boiler may be
operating at high supply and return temperatures. If the return water temperature to the Heat Pump rises above 65°C it
will generate a system fault (“excessively high water temperature”). To prevent this happening, the System Controller will
directly switch off the heat pump if the return temperature rises above a set limit.
Return water temperature (TRET) > EP13 + 0.5K
Heat Pump is switched off
Return water temperature (TRET) < EP13 - 0.5K
Heat Pump may be switched on.
Parameter Settings
•
EP13
Heat Pump Maximum Return Temperature (default 60°C)
This value should not normally need to be changed.
note
Engineering Parameters (EP) are only available for service engineers.
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4.5.5. Heatpump operating limits
function
•
Heat Pump operation is only possible within certain temperature ranges as defined below. Parameters are provided in
order to adjust the working area if required to do so by Hitachi.
The Heat Pump water temperature setting sent by the System Controller is always constrained to lie between the
maximum and minimum limits defined by the operating limits.
If the outdoor temperature is below -20°C (P14 in Config 3,4,5 / EP14 in Config 1,2), the heat pump will always be
switched off.
Heat Pump Working Area
•
