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  

Metran Swimming Pool Heat Pumps

The Air to Water Metran Swimming Pool Heat Pumps are available in both vertical and horizontal air discharge options.   Depending upon the installation location there are also options for the outer casings of the Swimming Pool Heat Pumps namely; powder coated steel, UV stabilized ABS or stainless steel.   The main feature or “heart” of the Metran Swimming Pool Heat Pump is the patented titanium heat exchanger.  Without an effective and durable heat exchanger a swimming pool heat pump will become ineffective in a very short period of time due to the rapid deterioration of incompatible components.  For example; the advantage of the titanium heat exchanger over a cuprous nickel alloy heat exchanger is that it is not susceptible to the highly corrosive chemicals (particularly high levels of chlorine) that are generally present in all swimming pools and spas.  The external casing component of the titanium heat exchanger is a fully molded non-corrosive, high impact strength material that can withstand high water pressures as well to ensure durability and maximum performance of the complete Metran Swimming Pool Heat Pump at all times.

Scroll compressors are used because they have 50% fewer moving parts than standard piston type compressors. This equates to greatly improved reliability and improved efficiency as well as reducing noise levels to a minimum.   The Digitally-based microprocessor can control water temperature to within 1ºC of the set point.  The controller also permits the user to pre-set different pool and spa water temperatures and it can also prevent unauthorized tampering by the use of locking controls via a Celsius control key.  The versatility of the Metran Swimming Pool Heat Pump is again demonstrated by its capability to heat and cool a swimming pool or spa in different climatic conditions.  This allows the operator to have full control all year round.   The Metran Swimming Pool Heat Pump can warm your pool or spa with the reliability and efficiency of our other heat pumps, but with the flip of a switch, it can also cool your pool or spa to refreshing temperatures during hot summer months. For cooler climates, heating & cooling heat pumps offer unique advantages over the passive defrost models.

The Metran Swimming Pool Heat Pumps are also hot gas defrost heat pumps that are uniquely equipped for an active defrost cycle.   Active defrost involves directing hot refrigerant vapor to the heat collector thereby melting accumulated ice away in a matter of a few minutes and then allowing the heat pump to return back to normal heating cycle.  Standard defrost heat pumps may remain off for extended periods when defrosting during very cold weather.  However, because of the hot gas defrost function on the Metran Swimming Pool Heat Pump it has the ability to continue to operate-even during freezing weather.  Hot gas defrost models will extend the swimming season longer than any standard-defrost heat pump.  A large variety of Models are available ranging from 4 kW heating output right through to 149 kW heating output which will ensure a suitably sized product can be selected from the calculation chart for any project.

By Mel Peatey

Solar Thermal Collectors Connected to Heat Pumps

There can be some advantages gained by connecting Solar Thermal Collectors to Heat Pump water heaters, but there are some important points to assess before this combination can be recommended.  The first point to consider is the economics of the project.   In other words will the addition of Solar Thermal Panels provide sufficient reduction in traditional energy use, which can then be calculated as a cost reduction when compared to the actual initial cost of supplying and fitting the Solar Thermal Collector Panels?

                                                              Schematic Image Only

There is an unwritten expectation for energy efficient products such as Solar Thermal and Heat Pump systems to provide a reasonable “payback” period, and this can sometimes be linked to the expected life cycle of the system or probably more closely linked to the warranty period offered for the products involved.   If the capital cost can be recovered within the warranty period then it is worth being given further consideration. However, when assessing the value of adding Solar Thermal Collector Panels to a Heat Pump installation it must also be remembered that during the daylight hours when the Solar Thermal Collector Panels could be contributing to the energy input of the system, that is also the period of each day that the Heat Pump units would be operating at their highest efficiency as well so the amount of purchased (input) energy for the Heat Pump units during the day time period could be between 3½ to 4.0 times less than the actual output that is produced in the form of hot water depending upon geographical location, ambient temperature and humidity.

The thermal contribution to a Heat Pump system from Solar Thermal Collector Panels is governed by the amount of radiation that is available at any given time and this can be intermittent because of varying weather conditions.   Therefore it is important to recognize that the Heat Pump units must be considered as the primary heat source and sized accordingly to be able to meet the total hot water requirement of the project due to the reliability of Heat Pumps being able to produce energy efficient hot water in all conditions including daytime, night time, as well as cloudy or rainy periods.  The Solar Thermal collectors will therefore only provide supplementary energy input during periods when there is a favorable level of radiation available for collection.  A number of factors can influence the decision to add Solar Thermal Collectors to a Heat Pump installation or not, but generally it has been found that in Regions where Government or Utility incentives are offered for the inclusion of Solar Thermal Collector Panels and the value of that incentive covers the cost of the Solar Thermal Collector Panels then obviously the economic equation is positive however, when no incentives or subsidies are available then there are some questions that need to be asked as to the added value of the Solar Thermal Collector Panels fitted to Heat Pump Units.

By Mel Peatey

Water to Water Heat Pumps

Another option for Commercial/Industrial Heat Pump water heaters is the Water to Water - or hydro sourced Heat Pump.   Water source heat pumps (WSHP) are specialized types of heat pumps that can also be used as reverse cycle or multi function units that use water as a heat source when in the heating mode and as a heat sink in the cooling mode. In the Water to Water HeatPump, heat is absorbed or rejected in a fluid medium rather than from the ambient air. Water loop heat pumps (WLHP) use a circulating water loop which could be from a chiller/cooling tower system as the primary heat source for the liquid refrigerant causing it to vaporize before moving it to where it is upgraded by an electrically-driven compressor and is then subsequently delivered at a useful super heated temperature for heating potable water via a suitable heat exchanger.

A typical schematic of a multi function Water sourced Heat Pump shown above indicates how in some cases a single Water to Water Heat Pump Unit can be used to provide hot water, air conditioning, as well as under floor heating if required.   In the schematic layout above the primary heat source can be provided by any medium (ground, lake, sea water or hotel cooling tower circuits) where heat energy can be captured (transferred) in the primary evaporator in the Heat Pump Unit.   These types of Heat Pumps can also be used very effectively for just the hot water output function depending upon the project requirements and still have the capability of delivering a very high Coefficient of Performance (COP) outcome of over 370% more than the actual energy consumed.   However, when used as a multi function unit for example, delivering hot water and air conditioning in an ambient temperature environment of around 24ºC the combined COP’s for both functions can be as high as 700% more than the energy consumed for the operation of the system.

By Mel Peatey.

Difference between Heat Pumps and Diesel or Gas Fired Boilers

In years gone by heating sources for large volume Commercial/Industrial Water Heaters have mainly been in the form of diesel or gas fired boilers.   These systems have always been afflicted with some disadvantages such as heating inefficiencies and the rising cost and the vulnerability of supply in some cases for these fuel types.  In addition there has also been a need to duplicate these systems with stand-by units to ensure continuous operation in the event of a breakdown or maintenance requirements.   The heating inefficiencies are caused – because only a low percentage of the gross energy that is produced from “burning” the diesel or gas, is actually transferred to the water or other fluid that is being heated.   This percentage of energy input can be between around 75% for new systems down to as low as under 50% for older systems.  The main cause of energy inefficiency in diesel or gas fired systems is that a good proportion of the heat that is generated through the burning process of these fuel sources is dissipated into the atmosphere through the flue pipe or chimney.   Further inefficiencies (up to an additional 30% reduction) can be experienced if the diesel or gas fired systems (in a Hotel for example) are required to heat the water to steam (100ºC) and then that steam is directed to a calorifer type storage tank to produce potable water at 60ºC for circulation to the various fixture points.    
In most cases when a diesel or gas fired boiler is initially installed it has to be duplicated with at least one additional identical system as a stand-by unit that will be able to handle the full hot water load requirement when the primary system requires repair or maintenance.   During these repair or maintenance periods the complete diesel or gas fired system is totally shut down and cannot contribute in any way to the heating requirements of the project; therefore the need for a stand-by unit.   However, the larger Commercial/Industrial Heat Pump products that are now available are normally fitted with multiple Heat Pump modules in the one unit that are digitally controlled in such a way that they can operate individually or together at any given time.   Provided the Heat Pump daily run cycle design is done correctly for each project there is usually no requirement to include any stand-by units thereby contributing positively to the reduction in capital cost and subsequently having a positive effect on the ROI equation.   The design of the system is critical in order to maximize the daily run cycle and at the same time keeping the daily run cycle at a suitable operational percentage that will allow the system to still contribute effectively even if one of the Heat Pump modules is isolated for service or maintenance at any time.  The non requirement of stand-by units for the Heat Pump alternative also reduces the amount of occupied floor space required in the building to house the heating systems.
Finally, a Heat Pump solution also provides a positive effect on the operating cost due to the energy efficiency of its design.   Whilst diesel or gas fired boilers produce a negative Coefficient of Performance (COP) because of the various heat losses that are experienced during their operation, a Heat Pump will actually produce a positive COP that provides a heating output in the form of hot water of somewhere between 360% to 400% more than the energy that is actually consumed by the system depending upon regional ambient and humidity weather conditions.   Heat Pumps are also capable of operating effectively in most areas of the World during the daytime, night time, or rainy and cloudy periods.  
By
Mel Peatey