What is HVAC and Ducting?

What is HVAC and Ducting?

Here at I-Sells, as the number 1 supplier of venting and ducting solutions in the UK, we endeavour to bring you the necessity of a properly ventilated home alongside all of the benefits that can be experienced. In this article, we will be answering the question ‘What is HVAC and ducting?’

All of the solutions we offer are in an effort to disrupt the environment necessary for mould to formulate, as mould can have serious health implications as well as spread easily if left unattended.

Alongside mould control, our venting and ducting solutions also aid in the removal of condensation, retention (and in some cases addition) of heat, and the removal of stale air in your home.

What is ducting used for?

The ducting system is a series of interconnected hollow tubes dedicated to the movement of air, ducting pipes can come in different sizes and as previously mentioned, in different shapes, each of which has its own benefit.

Ducting pipes can be as long or as short as required in accordance with the space it is occupying. Additionally, ducting can be created from different materials, as we will highlight below.

Ducting is used to facilitate the process of ventilation, ducting systems may vary, but generally are made from plastic or metal & made into piping which intakes air from the room it is in & expels it outside.

The main purpose of ventilation is to introduce outdoor air into a dwelling, building or room being evenly distributed. Its general purpose is to allow “healthy” air for breathing & diluting pollutants that may be present in the dwelling, building or area.

As a result of this fresh air, it prevents mould from growing as it disrupts the environment it needs. There are many devices and systems in recent times that can help to facilitate this function on an industrial level all the way to a local level like in your home.

Some ventilation purely extracts the air of the room it is in, whilst others extract the inside air and then recycle and return it.

Signs your home isn’t ventilated

Improper ventilation of the home usually leaves signs you can notice, which include:

  • There is almost always condensation on the windows or walls
  • Odours linger in the house for extended periods of time, especially in the kitchen or bathroom
  • High humidity, leading to wood rot or mould
  • You can’t see it working (in the case of a cooker hood, for example, you can’t see smoke or steam travel directly up it)

Ducting is used in order to create an isolated airflow for extracted air to travel through. These systems aid in creating a home with fresh air and help to regulate the temperature in order to prevent the cultivation of mould and dampness.

Ducting aids in mould prevention

Mould reproduces from tiny spores. The spores float through the air and deposit on the surfaces. Under adequate temperature, moisture, and nutrient conditions, the spores can form new mould colonies. 

Condensation is not the only cause of mould, it can occur from leaks in the structure of a building too. Ducting and ventilation can help prevent an environment necessary for mould to develop.

Mould can severely affect your immune and respiratory system, as the spores are easily breathable and not obvious to see through the human eye.

If you have found mould in your home, you need to assess if this is your landlord’s responsibility (for example it could be from a leaking roof that needs repairing). Or if the damp is caused by improper ventilation. To assess your options, click here.

What is HVAC and Ducting?

HVAC stands for ‘Heating, Ventilation and Air Conditioning’. HVAC systems are used in order to control the environmental conditions in a home or property. Environmental conditions can refer to the flow of air, or temperature, or both.

Ducting is the conduit for transporting air, ducting can be made from metal or plastic, and can be shaped as round pipe ducting & flat channel ducting. Ducting is necessary in order to facilitate the movement of air within ventilation and air conditioning, therefore ducting is a part of HVAC.

What are the three types of HVAC?

As mentioned before HVAC is the combination of three components, these are:

  • Heating – We use heating to make a space warmer, to provide comfort as well as safe working conditions. Heating can be altered via heating units as well as air conditioning units.
  • Ventilation – Ventilation is the process of replacing indoor air with fresh outdoor air, this process can help to remove allergens, dust, humidity and smells. Untreated humidity in a home or property is a key factor in the cultivation of mould. Which is something we should avoid at all costs.
  • Air conditioning – Air conditioning is the process of treating the air in a space, depending on the unit you choose, they can cool or heat the air or remove allergens or dust, and in some cases, all of these things.

What is the difference between HVAC and AC?

Air conditioning is a category within HVAC. Air conditioning is used specifically for temperature alteration through an air conditioning unit. This can be in order to heat or cool the air.

Some often believe a fan is a form of air conditioning when it isn’t. Most cooling fans simply move air rather than actively cooling it like an air conditioning unit.

Round Pipe and Flat Channel Ducting

Round Pipe:

Round ducting has the highest airflow performance, this is due to a wider diameter increasing its free area. The lack of corners also decreases resistance within the pipe, which allows for higher airflow rates and higher rates of ventilation.

It is recommended for most applications where space is available for installation. Its main purposes are for long ducting runs, whole-house ventilation systems, HVAC systems, bathroom, toilet and utility room extract fan venting, or any occasion where high rates of extraction are required.

Round PVC ducting pipe can be used for venting exhaust odours and steam from cooker hoods, although flexible ducting may be easier to install in many instances. 

Sizes are available from 100mm, 300mm, 500mm and 600mm diameters, with sizes between these dimensions also available. Both round and flat ducting have smooth inner surfaces to reduce air resistance and noise.

Pros & Cons of Round Ducting



  • High Airflow
  • Difficult to conceal
  • Less friction
  • Poor results in low-pressure systems
  • Lightweight
  • More expensive than flat ducting
  • Corrosion-resistant


  • Better for high-pressure systems


  • Designed for HVAC systems


Flat Channel Duct:

Flat channel ducting is ideal when a low profile is required due to lack of space. It can also be concealed and flush fit against ceilings and walls or within voids.

Please bear in mind that as a result of a lower free area, there is greater pressure created within a duct run. It is therefore essential that you check the manufacturer information for the fan you are planning to install within the run. 

If the fan is extracting at a rate that is greater than the duct run can cope with, there is potential for the fan to overheat and burn out. This is both costly and unnecessary. 

Flat channel plastic ducting is generally used for installations requiring low extraction rates such as bathrooms, toilets, and utility rooms. Sizes available from 110x54mm to 310x29mm.

Pros & Cons of Flat Channel Ducting



  • Corrosion-resistant
  • Creates more noise within duct run
  • Lightweight
  • Poor results within high-pressure systems
  • Easy to flush fit and conceal
  • Increased air resistance
  • Ideal for low-pressure applications



Contact I-Sells for your HVAC needs

We at I-Sells endeavour to make sure our customers have all the information they need before choosing to invest in our mould solutions. Be sure to visit our blog page to gain knowledge on the wide array of factors and issues surrounding ventilation, mould, condensation, and much more.

We hope to have answered the question ‘What is HVAC and ducting?’

We understand you may have more questions, Please do not hesitate to contact us for more information with regard to whatever you may need our help with. If you’d like to send us an email, click here. For other contact options, see below:

Call us on 020 8463 9696

Visit us at our showroom:


Monday – Friday: 8:00 am to 5:30 pm

Saturday: 9:00 am to 12:00 pm

Sunday: Closed

15 St John’s Parade

Sidcup, Kent

DA14 6ES

United Kingdom

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