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CTC air source heat pumps

CTC are a Swedish company with a long history of making heat pumps for the cold Nordic winters.

They don’t have a huge presence in the UK.

General overview

A CTC air source heat pump generally has the following components:

  • Outdoor fan unit
  • Hot water tank
  • Controller
  • Inline filter
  • Buffer tank with temperature sensor
  • Primary pump and pipework.
  • Heating pump and pipework
  • Heat emitters
  • Diverter valve (Normally an Esbe valve)
  • Outdoor sensor
  • Temperature sensors
  • Room temperature sensor
  • Outdoor isolation switch and fused spur

CTC Outdoor fan unit

The outdoor fan unit in a large black/grey unit set outside.

Personally I think they were ahead of the times in terms of styling.

They tend to be very quiet and look modern.

The unit extracts heat from the outside air and transfers it into the primary pipework through a larger heat exchanger.

Hot water tank

CTC systems are no different to any other heat pumps in that they are generally paired with an unvented hot water tank.

The temperature sensor is fitted in a pocket in the hot water tank to allow accurate temperature measurements.

Controller

The controller receives information from the different sensor and controllers then gives command to other parts of the system.

The touch screen display allows access to all the readings and settings.

Inline filter

The inline filter is installed on the primary pipework going into the outdoor unit. A high flow rate is very important for the efficiency of the system. A clogged filter can have a massive impact on the flow rate so can impact the efficiency.

Buffer tank

Air source heat pumps work more effectively when they operate for longer periods of time. CTC heat pumps usually have a buffer so there is always a volume of fluid for it to heat up.

The fluid constantly circulates from the outdoor unit to the buffer tank allowing long periods of operation.

The controller knows the temperature of the buffer tank from the sensor fitted either in a pocket or on the surface of the tank.

Primary pump and pipework

The primary pump moves the fluid (water with glycol) from the outdoor unit to the diverter valve. The valve then move to send the fluid to either the buffer tank or hot water tank.

Heating pump and pipework

The heating pump moves the fluid from the buffer tank to the heat emitters through the pipework. It is a separate system to the buffer tank and hot water tank.

Heat emitters

The fancy name for radiators or underfloor heating. The heating pump moves hot/warm fluid from the buffer tank to the heat emitters. The radiators or underfloor transfer (or emit) the warmth to the room.

As the warmth is emitted to the room the fluid cools down. The fluid then circulates back to the buffer tank to be reheated.

While the system is heating your property this process is repeated over and over again.

Diverter valve

This valve allows the system to send heat from the outdoor unit to either the buffer tank or the hot water tank.

Outdoor sensor

CTC heat pumps (and most others) sense the temperature outside before heating the property. This allows the use of the minimum amount of energy to reach the right temperature. Known as weather compensation the temperature of the radiators changes depending on the external temperature.

On very cold days the radiators are hot. On mild days the radiators will be warm. Keeping the radiator temperature as low as possible reduces the amount of energy the system consumes.

Temperature sensors

Heat pump systems are designed to use the minimum amount of energy for your needs.

The heat pump constantly monitors the energy use through sensors on:

  • Flow pipework in property
  • Return pipework in property
  • Flow in outdoor unit
  • Return in outdoor unit
  • How water tank
  • Buffer tank
  • Outside temperature
  • Room temperature

By getting all the temperature together the controller determines the correct amount of energy to use to hit the target room temperature.

Room temperature sensor

Instead of a traditional thermostat CTC heat pumps use a sensor that relays the room temperature to the controller.

The required room temperature is set at the controller. The heat pump then checks all the other sensors and adjusts the flow temperature to hit the required room temperature.

Outdoor isolation switch and fused spur.

Before working on any electrical appliance it’s important to isolate the electrical supply.

Most heat pumps have a single isolator outside beside the outdoor unit.

CTC systems seem to have an isolator that tuns the power off to the outdoor unit and a fused spur that turns the power off to the controller.

Both should be turned off before working on the system.

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