Currently, Air Conditioning Technicians are receiving many complaints about air conditioning systems that can’t seem to keep up with the heat. Typically, technicians check refrigerant pressures, superheat, subcooling, temperature splits, and system airflow. But these don’t always identify the problem. What happens when the system is performing as it should but the customer is still unhappy with the results? One way to explain what is happening is to use the analogy of a boat with a bilge pump. Bilge is the nasty water that collects in the lower reaches of boats. Bilge pumps are designed to pump that water out. However, if the water coming into the boat exceeds the capacity of the pump to remove it, the boat will sink. There are two solutions: either get a bigger pump or fix the leaks. The house is like a leaky boat and the air conditioning system is the bilge pump. When we focus all our attention on the air conditioning unit, we are locked into the “get a bigger pump solution” while ignoring the more obvious solution: fix the leaks. If you had a boat with a big hole, would your first thought be “I need a bigger pump”? I would want to fix the leak.

Water leaks in boats are pretty easy to spot, but air leaks in ducts and houses are a bit harder to locate. That is why they are often ignored until the ship is sinking. Most of the time a properly functioning air conditioning system can overcome the added heat load from leaks in the house, leaks in the ductwork, and poorly applied insulation. However, when temperatures rise to the outdoor design point or higher, the system gets swamped with the extra heat load.

So how do we find the leaks? A blower door can be used to determine the amount of house leakage, a duct blaster can be used to identify the amount of duct leakage, and an infra-red camera can identify areas that are improperly insulated. Ideally, you would check these things during and immediately after construction so heat leaks can be addressed. However, many homes have never been checked. It makes sense to locate and correct heat leaks in the homes of customers whose systems are operating correctly but not maintaining temperature.  Doesn’t this cost the customer money? Well, yes it does initially. However, it saves money continuously thereafter. You should of course make sure the air conditioning unit is functioning correctly, but don’t ignore the effect of the leaks.