Getting the wrong size heat pump not only costs you more money, it can cause notable temperature differences inside your house, lead to poor humidity control, and put stress on the pump’s motor because it cycles on and off too frequently. There’s a lot to consider when you’re choosing a heat pump, but getting the right size is absolutely vital.
How Heat Pumps Are Sized – The Manual J Method
The Air Conditioning Contractors of America has established a nationwide approach to ensuring that all of the important factors are taken into account when contractors size heat pumps. This method is called Manual J, and it looks at eight aspects of your home and surroundings:
- The overall climate in your area.
- Your home’s size and layout.
- Your home’s insulation and how effective it is.
- The number of windows you have and where they are.
- The amount of air infiltration (how much outside air leaks in through cracks and doorways)
- The number of people living in the home.
- The temperature preferences of the people living there, and how they use the home.
- Other sources of heat in the home and the lighting.
Finding Out the Right Size for Your Home
You’ll need a contractor to accurately size a heat pump for your home. During the sizing, the contractor will spend a lot of time inputting numbers into a dedicated software program, but should also actively evaluate your home, for example, checking your insulation and asking about your family’s habits and preferences when it comes to temperature.
In some cases, your contractor might make suggestions in order to maximize the efficiency of your heating arrangements. For example, adding some insulation might be advised to reduce the size of the heat pump you need.
We use the Manual J method whenever we size heat pumps, but this isn’t the norm for every company. Some homeowners have to actively request Manual J evaluations, and may be met with blank stares. The approaches used instead generally lead to over-sizing, reducing the efficiency of the system and leading to poor control of humidity in the home.
This is why it’s important to request a proper evaluation rather than settling for a “rule of thumb” calculation: getting the wrong size for your heat pump can lead to a range of problems.
Conclusion
Software programs have made choosing an appropriate size heat pump look pretty easy, but getting an evaluation by a licensed, reputable contractor is still essential if you want an accurate result. If you want to save money and maintain a comfortable temperature in your home, you can’t depend on rules of thumb or amateur evaluation: you need an expert.
If you’re looking for a new heating system, call our friendly, knowledgeable HVAC heating technicians on 408-920-3910 to discuss your options, or follow us on social media for information on heating and cooling your home.