Section 1: Introduction; What Are The Benefits Of A Heat Pump; How A Heat Pump Works; Intended Use - Dimplex LA 6 MI Installation & Technical Manual

Section 1: Introduction

What are the benefits of a heat pump?

Large quantities of pollutants, such as carbon dioxide,
sulphur dioxide and nitrogen oxide are released from gas
or oil boilers used to heat our homes. A large percentage
of our energy supply comes from fossil fuels which have a
serious effect on our environment. Fuel security is also an
issue as our oil and gas reserves are limited and often
from volatile counties around the world. The way electrical
energy is generated will change in the future to favour
more renewable generation methods. A heat pump uses
electrical power that could come from a variety of sources
and it uses very efficiently.

How a heat pump works

A heat pump converts low grade heat from the
environment to high grade heat for space and DHW
heating using a refrigeration cycle. Surrounding air is
drawn in by the fan and passed over the evaporator. The
evaporator cools the air, i.e. it extracts heat from it. This
extracted heat is then raised in temperature via the
refrigeration cycle and then transferred to the condenser.
The heat is "pumped" to a higher temperature level by
increasing its pressure with the aid of an electrically driven
compressor.
Because the energy extracted from the air is transferred to
the heating water, this type of device is called an air-to-
water heat pump. The air-to-water heat pump consists of
the main components evaporator, fan and expansion
valve, as well as the low noise compressor, condenser
and electrical control system.
At low ambient temperatures, humidity accumulates on the
evaporator in the form of frost reducing the transfer of
heat. The evaporator is defrosted automatically by the
heat pump as required.
The refrigerant circuit is hermetically sealed. It contains
the Kyoto protocol approved refrigerant R410 with a GWP
value of 1725. It is CFC-free, does not deplete ozone and
is non-flammable.
Correct selection of the heat pump, heat
emitters and circulation system is essential for
efficient operation of the entire system.

Intended Use

This device is only intended for use as specified by
Dimplex as detailed within this technical manual. The air-
to-water heat pump is to be used exclusively for the
heating of heating water in a closed circuit. Any other use
beyond that intended by the manufacturer is prohibited.
Persons, especially children, who are not capable of
operating the device safely due to their physical, sensory
or mental abilities or due to their inexperience or lack of
knowledge, must
supervision or instruction by the person in charge.

Air as a heat source

The decision whether to install either an air source heat
pump or a ground source heat pump depends on the
following factors:
Investment costs:
In addition to the costs for the heat pump and the
heat emitter system (radiators and circulation pump),
the investment costs are heavily influenced by the
costs of tapping the heat source. Air is the easiest
heat source to tap as the heat pump is relatively
easy to position outside. Tapping the ground as a
heat source is more difficult. If the land area is
available horizontal loops are the most cost effective
way to install the ground collector. If boreholes are
used, due to the cost of mobilising the plant,
experience has shown that installations with less
than 10 boreholes are not economical.
Operating costs:
The seasonal performance factors of the heat pump
influences the operating cost. These are primarily
affected by the type of heat pump, the average heat
source temperature and the required heating flow
temperatures. Ground source heat pumps have
higher SPF‟s compared to air source heat pumps.

Advantages of inverter compressors

An inverter heat pump is able to modulate its‟ heat output
over a set range. The inverter compressor modulates its
output to keep the return temperature constant. If demand
increases the output of the compressor can increase to
keep the flow temperature constant. If the demand
decreases beyond the minimum setting of the compressor
it will turn off until the heating circuit temperature reduces.
A fix speed compressor will run at a constant speed until
the set temperature is reached. When the set point is
reached the compressor will turn off until the temperature
in the heating circuit drops to a hysteresis value. When
this value is reached the compressor will restart. The
compressor will cycle on and off to maintain the correct
temperature. If demand increases the fixed speed
compressor will be on more often.
Even though an inverter compressor cycles less, to ensure
optimum life expectancy an inverter compressor should
always be installed with a buffer tank to increase run times
and store energy for the defrost.
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not operate this device without