High Temperature Heat Pumps

High Temperature Heat Pump

The Metran High Temperature Air Source Heat Pumps transfer heat from the ambient air to water, providing high-temperature hot water up to 80°C. The unique high-temperature heat pump is widely used for house warming in the cooler climates as well as Commercial/Industrial applications, particularly in the tropical zones of the World.  With innovative & advanced direct heating technology, the heat pump can operate very well at ambient temperatures as low as 0℃ whilst still being able to generate high output temperatures of up to 80℃.  This ensures compatibility with normal sized radiator, based systems without the need for any supplementary energy source. Compared with traditional Diesel fuel or LPG boilers, the high-temperature heat pump can produce up to 50% less CO2 whilst saving up to 80% in operating costs.  The Metran High Temperature Heat Pumps are not only highly efficient, but are also easy and safe to operate.

Intelligent Digital Controller

The high temperature delivery from this new design of Air to Water Heat Pumps is achieved by using a combination of high efficiency American Copeland scroll compressors, environmentally safe R134a refrigerant, electrically activated expansion valves, larger evaporator design and specially designed high efficiency tube in shell heat exchangers.  A user friendly intelligent digital controller with blue LED back lighting is incorporated with the Heat Pump unit to easily adjust temperature setting to suit any application.  The electrical compartment is provided in a separate, isolated compartment to avoid internal corrosion and subsequently contributing to extending the operational life cycle of the Heat Pump unit.
In all cases each project design, followed by the correct High Temperature Heat Pump model selection is critical in order to maintain the required performance criteria and the durability of the system.  In addition, installation recommendations of clear, unobstructed minimum space clearances around the Heat Pump systems must be observed in order to maximize the performance and minimize the operating costs.  It is also advisable to mount the Heat Pump(s) on a solid concrete foundation and using shockproof bushes at the anchor points to maintain stability of the system, and reduce noise and vibration that may eventually contribute to damage of plumbing the connections. 

By Mel Peatey  

Solar Thermal Panels and Heat Pumps Hybrid Systems

Figure 1

The addition of solar thermal panels in conjunction with Heat Pumps to form a hybrid system certainly does have the capability of creating a complete energy efficient solution for any hot water installation regardless of volume requirements.   Solar thermal panels will contribute their maximum free “solar” energy only during the daylight hours when the sun is shining brightly and without any cloud cover.   Air to water Heat Pumps on the other hand will continue to contribute free “solar generated” energy from the air during the daytime, rainy or cloudy periods, as well as night time.  Another point to consider is that air to water Heat Pumps will operate at optimum efficiency and therefore contribute the maximum level of free “solar generated” energy during the same periods of the day as the solar thermal panels which is, during the highest ambient temperature periods of each day.   Therefore when solar thermal panels are used in conjunction with Heat Pumps in a hybrid system the “actual” achievable saving in energy will be reduced because both systems enjoy a “positive” COP.  When the Solar thermal panels are contributing the maximum amount of free “solar” energy, the Heat Pumps will also be contributing the maximum amount of free “solar generated” energy from the air.

Figure 1: above shows a typical layout with solar thermal panels connected with Heat pumps. The daily energy contributed by solar thermal panels can be calculated by using the following formula:

kW = Collector area x Collector efficiency x Average Daily Radiation (Mj/m²) ÷ 3.6

Figure 2

In addition, solar thermal panels actually lose efficiency as the water temperature rises as shown in the chart - Figure 2.  For a good quality solar thermal panel operating in the highest instantaneous solar radiation conditions it can be seen that the efficiency at a point where the temperature difference between the solar panel and the ambient temperature is around 30 degrees Celsius the efficiency is approximately 75%.  If we select as an example the average daily radiation of 17.56 Mj/m² per day for Manila Philippines the equation would be:

 kW      = 1m² x 0.75 x 17.56 Mj/m² ÷ 3.6

            = 3.66 kW/m² per day of available solar collector aperture area.

Therefore, during the maximum energy collection period for the solar thermal panels they will contribute approximately 3.66 kW of energy for every one square metre of collector aperture area that is installed.  In the same location (Manila - Philippines) during the same period & same climatic conditions that has been used to assess the solar thermal panels, the Heat Pumps would also be operating efficiently and producing a COP of approximately 3.8 to 4. 
Then assuming that the solar collector panels were NOT installed as part of the hybrid system and only the Heat Pumps were required to contribute the total energy requirement during that same period.  The 3.66 kW/m² per day of “free” energy contributed by the solar thermal panels would only require approximately 0.96 kW of energy to be “consumed” by the Heat Pump to produce 3.66 kW of output using a COP of 3.8 for the Heat Pumps.  However, in the location of Manila – Philippines during the peak high ambient temperature periods the COP for the Heat Pumps may even be around 4 of higher which would result in even less energy to be “consumed” in order to produce 3.66 kW of heating output.  Therefore, the lower calculated energy consumption, for the Heat Pumps that would be required to produce the same heating output as the solar thermal panels becomes the “actual” or real amount of energy saving that should be used to calculate the ROI or payback in relation to the cost of supplying and installing the solar thermal panels in a hybrid system with Heat Pumps.

By: Mel Peatey.

Heat Pumps compared to Solar Water Heaters

An Air to Water Heat Pump provides an ideal energy efficient hot water system alternative for both domestic household use, or for larger Commercial applications.  In reality a Heat Pump provides slightly less energy savings when compared to a domestic solar water heater, but there are a number of other significant advantages associated with the use of an Air to Water Heat Pumps.

One major advantage of the Heat Pump is the aesthetic appearance that is gained by not needing any thermal solar panels and in some cases a storage tank on the roof of the building to ensure efficient operation.  In some cases roof structures may have to be reinforced when they are required to support the weight of a domestic sized solar storage tank that can weigh in excess of 400 kg.  In addition, the installation cost of an Air to Water Heat Pump is very simple compared to the installation cost of a solar water heater, and this significantly lower installation cost for the Heat Pumps should also be taken into consideration when assessing the overall installed cost of either product alternative.

Another advantage of the Air to Water Heat Pump is the low energy input from the electricity supply that is required to operate the system, while at the same time producing an output of around 3 times more than the actual electrical input, when operated in average ambient temperatures of 20 degrees Celsius.  This results in an energy saving (reduction) of approximately 75% when compared to traditional electric water heaters.  In Regions where the average ambient temperature is higher than 20 degrees Celsius the actual energy savings can be higher due to the extra heat energy that is available from the ambient air in these locations.  Air to Water Heat Pumps do not require direct sunlight to operate efficiently because they collect free energy from the ambient air.    Contrary to popular belief, a solar water heater does requires back-up electrical energy to operate the booster element during periods of inclement weather, low radiation periods, and at night time when there is a need to supply hot water during those times.  When comparing similar volumes of hot water delivery the annual booster or back-up energy needed to ensure solar thermal water heaters provide a continuous supply of hot water during all weather conditions, or if hot water is needed during the evening period, is similar to what is expended annually for a Heat Pump to drive the evaporator fan and compressor.   A domestic sized Heat Pump could, in some cases, operate from Photovoltaic (PV) solar cell system due to the low energy input needed when compared to the actual output that is delivered in the form of hot water.  This makes the Heat Pump products ideal for isolated and heavily forested locations such as remote Eco Resorts.

By Mel Peatey.