How to House Hunt Like a Home Inspector -Cooling/Heat Pumps
As I write this post, it’s the middle of a very cold winter where I live in Canada. So why would I be thinking about cooling systems at a time like this? Well, heat pumps that are used to heat homes are based on the same principles as air conditioners. We’ll include them in the discussion. This is part of the series “How to House Hunt Like a Home Inspector” that talks about how home buyers can use the perspective of a home inspector to get to know the house better before they buy. See other posts at www.http://goldeyehi.ca/blog/
Let’s start by talking about how these systems work. It’s a complicated process and can get technical but I’ll try to summarize in general terms. This description will be considered an over-simplification by many home inspectors and technicians who work on these systems. But for the purposes of this series a more general understanding is what’s important. Cooling systems (air conditioners) and heat pumps work in the same way but in opposite directions. They extract heat from one environment and dump it to another- usually in the opposite direction of what seems natural. For cooling the house, heat is extracted from the house and dumped into the warmer outside air. For heating the house, the heat is extracted from cooler outside air and dumped into the house. How is this possible? It’s possible because of the properties of the gas in the system’s pipes. When it is compressed, it gets hotter and when the pressure is released it gets cooler.
Let’s look at how this works in the air conditioning system. Outside of the house, there is usually a compressor and coil of some sort. The compressor compresses the gas (actually turns it to liquid) which makes it heat to a temperature that is higher than the warm outside air temperature. The air outside is then used to cool this hot liquid down (ie the heat is dumped outside). Next, the pressure is released from the liquid which makes it even colder. Then back in the house, it is used to cool the house air (ie the house heat is transferred to the gas). There are a lot of variations on this theme, including heat pumps that work in the reverse direction- extracting heat from cooler outside air and dumping it into the house. Some systems use water, rather than air as the source to extract heat from or the target to dump heat to, inside or outside the home. Some systems are reversible and can do both. Geothermal systems, for example, can capture or dump heat to ground water depending on whether it’s the heating or cooling season.
As I said, it’s complicated. So how on earth is the average person supposed to be able to view this with the eye of a home inspector? Well, you don’t have to know the details about how a system works to watch for issues. Just keep in mind two things; 1) What the system designed to do (cool and/or heat the house) and 2) There are almost always two parts to the system, the one inside and the one outside.
So, when walking through a house that you’re interested in buying, be aware of the temperature- is the system doing its job? Are there areas that feel excessively warm or cool? Obviously, you can’t assess a cooling system’s effectiveness in the middle of winter, but you can look at the parts of the system to see if there are any visible issues.
The outside part of air conditioning system may use air flow to transfer heat or may use water from a lake, river or in the ground (geothermal). Water based systems are specialized technology and you probably won’t be able to see enough to inspect it properly. It would be wise to have water based systems properly inspected by a qualified HVAC (heat ventilation air conditioning) technician with experience in the specific type of system found in the home.
Cooling systems that use exterior air for the heat transfer usually have a unit sitting on the ground or mounted on the exterior wall of the home. If it isn’t buried in deep snow cover, take a minute to take a closer look at the unit. The lifespan and reliability of the unit is usually related to how well it has been maintained. If it’s for cooling only, it should be covered in winter. All exterior units should be kept clean and free from overgrowing plants and debris to ensure good air flow and efficient heat exchange. It should be kept level to protect the compressor and ensure it works efficiently. Does it look old, dirty or corroded? Are there any signs of oil leaks (coolant gas may have leaked and the system may need recharging)? How close is the unit to any vents that might be discharging heat from a clothes dryer, fireplace or furnace? These can make the system less efficient if both are operating at the same time, or can result in condensation, frost and ultimately corrosion.
If you’re house hunting during the cooling season (summer) and the system is operating, try to be close to the unit as it’s operating. Listen for excess vibration or noise. Also take note if the unit is operating continuously or is turning on and off at short intervals. These may be signs that the system is sized incorrectly. There are several other issues that might trigger these symptoms and you should have a qualified HVAC technician service the system.
Inside the home, the heat exchange may occur at a furnace air handler (central air conditioner) or a dedicated fan unit mounted on a wall (split systems). In both cases, you can look for a couple of issues. There will usually be some condensation created when air is cooled, and there should be a condensate drain and sometimes a pump will be required. You can often see signs of condensation leaks on the side of a furnace below the condensate drain line. Since this is usually above the air distribution fan and heat exchanger of the furnace, there is risk of corrosion damage to the heating system. You’ll want to make sure this is dealt with quickly.
If there is a pump to handle the condensate, check that all the lines are connected all the way to the drain and that there are no signs of leaks. Like hidden plumbing leaks, condensate drain leaks can exist for a long time before discovered and can cause ca lot of damage.
We’ve talked about some things that you can be aware of and can look for as you walk through a home with the approach of a home inspector. But cooling/heat pump systems are complex and it’s not always easy to figure out what each part does. A Home inspector is trained to understand the systems, how they typically fail, and how to spot the signs of issues. They can alert you to potential problems that may not be evident when you are house hunting. When there are signs that the systems aren’t working properly, a good Home Inspector will call for further evaluation or repair by a qualified specialist, in this case an HVAC technician.
A qualified HVAC technician knows the specifications and requirements of individual systems and the best solution to correct problems. They will work with the proper permits to ensure that the work is not only done right, but that it is documented to satisfy the municipality and avoid issues later.
Cooling and heating systems provide occupants with a comfortable environment to live in. But we rarely think about them when they are working correctly or when they are not needed. By being aware of the issues and looking at a house with the approach of a home inspector, you may be able to spot issues and assess their implications (and associated costs) before you decide to make it your home.
Steven Schroeder 2017-01-02