Simcoe Air Source CO2 Heat Pump

Transom CO2 Heat Pump logoWith all the decarbonization projects and directives currently underway the next step is the CO2 based heat pumps. The Simcoe Heat pump comes in a 20 and a 40 ton model that can be expanded to 12 modules.

CO2 Heat Pumps – Simcoe

Side-profile image of Simcoe CO2 Heat Pump

The Simcoe Air Source Heat Pump is designed with environmentally friendly CO2 refrigerant. This means that it has an Ozone Depletion Potential of zero and a Global Warming Potential of 1. The R744 Refrigerant fits into all regulatory requirements.

The Simcoe CO2 heat Pump brings many advantages to this design. For instance, it can generate very high leaving water temperature over a very large ambient operating range. The heat pump can generate 190°F from -10°F ambient temperature.

Designing a CO2 heat pump means it will operate in the transcritical region. The Simcoe Heat Pump takes all this into account, allowing for all the operational requirements to gain the most of the system.

The Simcoe Heat Pump is designed with a double-walled gas cooler so that it can be used directly with potable water. The heat pump does not need a secondary heat exchanger skid, as required by other heat pump manufacturers. The Simcoe Heat Pump has an option for a single-walled gas cooler.

North American Manufacture

The Simcoe Heat Pump is the first air sourced CO2 commercial/industrial heat pump manufactured in Norm America. All the design and manufacturing knowledge is based from here and is readily available for your application and aftermarket support.

Domestic Hot Water Projects – Potable

The Simcoe Air Source Heat Pump design is transcritical and operates optimally with a high delta T. This makes it very effective for single pass domestic hot water system. The Simcoe unit has a built in double walled heat exchanger. This way there is no need for a separate heat exchanger skid to get the second wall for the domestic water application. Others require the HX skid that also includes a circulating pump, expansion tank, glycol fill tank, aeration valve, buffer tank etc.

It also uses a control strategy to vary the set point to boost the water temperature to prevent Legionella. With single pass and stratified tanks, the efficiency can be increased by 23%.

Simcoe Features

Simcoe CO2 Heat Pump internals

The main feature of the Simcoe Air Source Heat Pump is that it has:

  • Variable capacity
  • Variable fan speed control
  • Variable pump speed
  • Variable backup/trim heat
  • Variable regulating valves

With these features, the Simcoe unit is designed to fit into the Domestic hot water applications and then modulate as needed.

Capacity Control

With the Simcoe Air Source Heat Pump units, the capacity generates varies with the ambient temperatures. This will result in the capacity generated higher ambient temperatures being greatly increased. If this is not addressed then it will lead to excessive cycling of the compressor which in turn, will lead to greater fluctuation in the system supply temperature. With the Simcoe Air Source Heat Pump, it is designed with variable capacity compressors. This way high discharge temperatures can be generated while keeping the compressor running with in proper cooperating conditions.

The Simcoe Air Source Heat Pump control strategy utilizes a dead band system which will maintain the supply temperature within 2°F. It will unload the stages as the load requires it.

With larger loads multiple units can be used which will give large turn-down capabilities. As well, an extra module can be added to allow for back-up (N+1).

Simcoe Air Source Heat Pump capacity control chart

The controllers are available with optional BMS communications like BACnet and Modbus.

Simcoe C02 Heat Pump with service panel doors open


The Simcoe Air Source Heat Pump utilizes defrost rides imbedded in the air coil. This will eliminate the need for reversing the system in the middle of winter, which would generate chilled water, undoing some of the heating load already generated. This way, the system capacity and COP remains high.

Supply Temperatures

A number of different design temperatures can be achieved with the Simcoe Air Source Heat Pump. It can generate leaving water temperatures from 130 to 190°F while operating at -10F ambient.

Potable Water

The hot water air source heat pump is built with double walled heat exchangers to be utilized for potable water directly.

As well, the controller is set up so that it will raise the temperature every time as designated by the user and to raise the setpoint up to 150°F to counteract the possibility of Legionnaires disease.
Internal image of Simcoe C02 Heat Pump

The Capacity Range

The Simcoe Air Source Heat Pumps are available from 48 MBH to 700 MBH at 45°F ambient temperature. With the modular unit configuration, controlled by the master controller, the capacity can be increased to 8400 MBH (12 modules).

Elec Trim and Back Up Heat

The Simcoe Air Source Heat Pump has an optional back up heat. It is integral with the heat pump so that no external or secondary elec power connection is needed. The heater is 0-100% variable capacity so that it will trim up the BTUs generated at low ambient temperature to produce a flat capacity line over the ambient range. It works in conjunction with the BIN hours resulting in a very low change in overall COP.

Secondly it can be used to recharged the storage tanks during the night to make the full storage tank available at full temperature to counteract tank temperature loss.

Built-in Pump

Simcoe CO2 built-in pump

The Simcoe Air Source Heat Pump has a built-in circulating pump. It is controlled in conjunction with load demand and the compressor. This way it does not dilute the stratified tank temperatures. The built in pump also means less installation cost. The pump is available at standard and high external pressure.

Heat Tracing

For potable water application the Simcoe Air Source Heat Pump has a heat tracing option. It is applied to all wetted parts internal to the machine and is further insulated. The heat tracing has a separate connection box. This allows users to connect their back up power system. Ensuring the heat tracing is functional at a power outage.
Simcoe CO2 internals

Drain Pan

Inside of the air coil the Simcoe Air Source Heat Pump is equipped with a stainless-steel drain pan. It has a removable grill and an access port. It is also equipped with heat tracing to ensure it is fully functional during the colder periods of the year.

Foot Print

The Simcoe Air Source Heat Pump lends itself to projects located in mid-density and high-density locations such as institutional buildings or high-rise buildings. The Simcoe Air Source Heat Pump can be located on roofs, side yards, etc. It does not require large foot prints as utilized by other types such as ground source heat pumps.