Choosing the Right HVAC System for Your Home


It is really important if you are picking a replacement heating, ventilation, or air conditioning unit for your home that you select the best suited system. A really important aspect of replacement or brand new system is that it is the most suitable size. If the new unit is either too large or indeed too small then it will not be the most efficient system, which you could have had installed.

To work out what exactly is too large or too small the installer or fitter needs to work out what is required to keep the home warm in cold weather and how much air conditioning is needed to keep it cool in the warmer months. The values needed to heat or to cool homes can be worked out and is known as the load of the home.

The starting point for working out the load is to know the square footage of each home that requires an updated system. Yet it is more complicated than that and multiple factors have to be included within the calculating process. For example the load depends on the construction materials used, the quality of insulation, the size, type, and quality of doors and windows. The number of rooms, the prevailing climate, and the time of the year can also affect the calculation of the load as well.

The good news for contractors is that they no longer have to work out the residential loads by themselves. Though the mathematical formulas have not changed, much the calculations can be done using specialist software packages.

Whenever possible try not to arrive at a total load amount by using rule of thumb sums instead of the software. Rule of thumb workings out are more likely to be inaccurate. Such inaccuracies cost you more money as oversized heating and cooling systems use more energy, and are on more frequently.

Who can carry out load calculations?

Virtually any HVAC contractor that you contact to discuss fitting or replacing a system should provide you with a load calculation. All contractors should be able to work it out. If they cannot do so then you should seriously hiring any other contractor that can do so. These days some of the utility companies can also work out the load figure for you.

How large does the system need to be?

The size of the HVAC system that should be fitted is determined by the load calculations, so these are accurate then the system should be no larger or smaller than required. By size it is meant how much heat or coolness delivers and not its actual physical size.

Therefore the heating is worked out as the number of Bt’s per hour (But/h) while the level of cooling is worked out as the number of cooling tons, assuming that a single cooling ton equates to 12,000 BTU/h.

Then the SEER or Seasonal Energy Efficiency Ratio shows the energy efficiency of cooling systems instead of its capacity for cooling homes down.

The importance of installing the right sized cooling units

Having a system that is too powerful can lead to more problems than having one, which is not quite powerful enough. Air conditioning units work by cooling down both the temperature of the air (the sensible load) as well as the humidity in the air (or the latent load). Larger air conditioning units are often really good at reducing the sensible load but not the humidity. It is less effective at removing the excess levels of moisture in the air whilst increasing your energy bills. Oversized HVAC even increase the risk of mold developing within your home.

On the other hand, the correct size of the unit will be more efficient at cooling your home down. Besides lowering the air temperature, it gets rid of the humidity. With no humidity, the air temperature does not have to be lowered as much and keeps your energy bills lower too.

It is important to know the energy efficiency of each of the different systems that could be installed, bearing in mind that it is better to have units too few cooling tons than it is to have units that deliver too much. Too many cooling tons do not particularly make your home feel any cooler yet make a notable difference to the size of your utility bill.