Common misconceptions with HVAC systems

28-July-2020 12:08
in General
by Admin

Heating, ventilation, and air conditioning (HVAC) systems that run-in business, commercial and office buildings are of utmost importance. Properly designed and maintained HVAC systems help in controlling the temperature, humidity and indoor air quality. There are a lot of misconceptions about the installation of HVAC systems. We are going to discuss some of the most common air conditioning and heating myths to help keep your ventilation systems in good working order.

So, what are some of the most common misconceptions about HVAC systems? 

1) Misconception: Skipping regular air filter changes is acceptable.

Fact: Over time, dust particles and moisture block air filters making it harder forthe ventilation system to circulate air. Clogged HVAC air filters can cause serious mechanical issues in your air conditioning by blocking the coils – resulting in damage,
inefficient operation and possible early failure. Another factor to consider is ensuring air hygiene conditions are optimal with factors such as Covid-19 so filters should be replaced regularly to reduce the risk of bacterial transmission.

(An example of an AHU filter in poor condition)

2) Misconception: All air filters are easily changed

Fact: Filters attached to various HVAC systems are not always easily changed. Sometimes isolations are required to be made to the system from an electrical and mechanical perspective which is not always a simple task. Replacing filters incorrectly can cause serious damage, or effect air flow parameters and in some cases can create negative pressures. In the instance where pressures are significantly reduced pressure switches can pick up and cut out plant such as air handling units on fault. This type of scenario can be caused from putting a filter in back to front or using the wrong filter media type. Other issues can occur
when not regularly replacing a filter which can degrade and get drawn into the mechanical mechanisms such as fans. Calling for professional help in such instances is prudent. It is always practicable to let experts handle any sort of repair or maintenance issues on such expensive and sensitive systems.

3) Misconception: HVAC maintenance and repair are a waste of money for non-statutory
maintenance visits. Statutory maintenance would be an item such as a gas safety inspection
or an F-Gas inspection.

Fact: It is better to be proactive and catch problems before they become terminal. Routine maintenance of your HVAC systems acts as an investment; it allows inconsequential problems to be identified soon so that they can be repaired before any major failure.

4) Misconception: Turning your HVAC system off will reduce energy consumption.

Fact: While we all try to be in the habit of switching off lights and appliances to reduce energy consumption, the same functionality does not apply to your HVAC systems when a building is in full occupancy. By continually turning your system on and off can consume larger amounts of energy. In particular, older air conditioning systems require high voltages
to turn the compressors. Modern systems are able to modulate power, heat and cooling with 3 phase inverters, sophisticated BMS interface and smart controls.


5) Misconception: Closing vents increase energy efficiency

Fact: This is one of the most common misconceptions about the installation and use of ventilation systems – is that the closing of vents increases energy efficiency as the air flow is not being sent to a terminal outlet. This is incorrect, the closing of ducts in fact increases the air pressure in the ducts which can cause damage to the system by increasing the strain on fan motors, impellers and reduce efficiency and the proportional balance of the ventilation system when it was commissioned. This can lead to air flow being starved in some areas and increased above requirements in others.

6) Misconception: Thermostat locations do not matter

Fact: This is a common misconception, thermostats should not be located with exposure to sun (known as solar gain), near a vent or air conditioning outlet, behind furniture, appliances such as printers etc – doing so will have the effect of cutting out or incorrect temperature modulation of your systems too early due to inaccurate temperature readings.


(Example of when filter media in an Air Handling Unit
is damaged and being caught in the mesh prior to the


7) Misconception: Air conditioning external units should be covered in winter

Fact: Keeping your external air conditioning units covered in winter will not cause problems. Covering your external unit can potentially seal moisture and speed up corrosion of sensitive components. Your external AC units are designed to withstand temperature fluctuations so having them exposed is acceptable. It is also notable, that a majority of modern air conditioning units have ‘heat pump’ units, essentially reversing the cooling process to being able to provide heating. Covering an AC unit will cause the unit to fail and it will not be able to reject the cool air sufficiently.

(Example of a heavily clogged filter, this will reduce air
flow to the ventilation system.)


If you need help understanding your ventilation and AC systems and maintenance, please feel free to
call Karsons Consulting today 020 3282 7605 or