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Water Filter
Mitsubishi like a TF1 filter with their units, one comes with the unit, its installed already in the pre-plumb and combi
units.
Glycol / anti-freeze
In Monobloc heat pumps the water goes outside the building. The unit can protect itself from freezing up, but if
the power goes off there is a risk that the unit will freeze causing damage. To prevent this, we recommend putting
propylene glycol mixture in the system. It is important that the glycol concentration is adequate to protect the unit, if
the unit freezes up there will be no warranty. Manufacturer dependant, a mix of 25% is normal for UK conditions.
Adding too much glycol is not a good idea as it increases the water pump power and slightly reduces the capacity of
your system.
Heat meters
If you are using more than one heat source, heat pump + boiler you MUST measure the heat produced by the heat
pump and the electricity used. This is essential for RHI. The heat meter goes in the return to the heat pump with a
sensor in the flow. The electricity meter must measure only the power consumed by heat pump. See hybrid drawings.
Flow
In most heating systems, the flow rate through the unit changes with load, when all the heat emitters are open the flow
is high and when most of them are closed the flow rate reduces. In a heat pump, we cannot let this happen, we need
to keep the water through the heat pump at a constant speed. To balance the flow through the emitters and the flow
through the heat pump we need to allow for some bypass. This can be achieved in 4 different ways:
Low loss headers
A low loss header is a large pipe with 4 connections, a flow and return to the heat pump and a flow and return to the
heating circuit. If the flow rates either side of the header don’t match the water flows through the header making up
the difference.
The Cylinder
If you want to heat water with a heat pump you need a dedicated heat pump cylinder. These are 600mm diameter and
are pre-insulated and can store water at up to 3 bar pressure.
Ideally Cylinders should only be used IF the coil area is more than 2.5m^2. Smaller coils give very long recovery times
and increase usage of the immersion heater. Cylinders can be pressurised or open vented. We can work out the run
cost for you if you tell us the coil size.
What the unit comes with
and what you will need
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