For any customer the first consideration (beyond cost) for buying a new HVAC system is which brand to choose. The question is, how much does it matter? I will not tell you all brands are the same, but there is a part of your new system that is more important. The installer. You may think all installers go through rigorous screening and are well qualified. There are well qualified people in most companies, but they may never meet you or even see your house. “Nothing stops a Trane”, right? Actually a service technician that does not follow procedure can stop one dead in its’ tracks. It may take several years, too. Maybe you had a unit that could have lasted 25 years, but only lasted 11. Perhaps you had to change out a $1000 compressor because a tech did not know what a vacuum pump was years before. When it comes time to pick a HVAC company listen to your friends evaluations of who they have dealt with. Listen to the contactor or salesperson. We all know hot air when we hear it. Meet the guys installing the system. A little due diligence can go along way. You may pay $3000 for a system that should have cost $4500, but that does not mean you got a deal. If you replace the $3000 dollar system every 10 years and you replace the $4500 system every 20 years you are spending much more money per yer for less quality.
Heat Pumps: Why they should not be mismatched
How many people have had their heat pump’s compressor fail? How many live at the beach where the corrosive winds destroy the exterior of your outdoor unit? The solution seems natural. Buy a new outdoor unit and reuse the indoor unit. The blower section works so why would you want to pay to replace it? The reason is that the new, more efficient outdoor unit will not work with the old blower section. The issue that arises is the pressure problems in heating mode. In heating mode the compressor sends hot gas to the blower section to be condensed. The heat given off by the condensing gas is then taken by the blower and dispersed, thus heating the structure. Old blower sections in air handlers are paired with smaller, less efficient coils. These coils are not rated to handle the hot gas being given off by the new, efficient outdoor unit. Because of this fact the pressure can reach dangerous levels. I have repaired two heat pumps this winter that had to have some refrigerant removed because the pieces of equipment were mismatched. It can destroy the compressor, cause refrigerant leaks and void your new outdoor unit warranty. Always replace your indoor unit when possible so you can get the most from your HVAC heat pump system.
Heat Pump Defrost
Heat Pumps use refrigerant to both heat and cool. The refrigeration cycle is changed by a valve in the outdoor section called the reversing valve. I service customers in the Wilmington, NC area where it is just beginning to get cold in November. As the air gets colder you may start hearing heat pumps in your area defrosting. When a heat pump defrosts it switches into cooling mode. The reason this happens is because the hot refrigerant coming out of the compressor in cooling mode travels to the outdoor coil. This is the area of the system that forms ice during the winter. The outdoor fan motor will also shut off during defrost to increase the amount of heat the refrigerant retains. The process will send steam into the air, which on many occasions has prompted homeowners to believe their unit is “blowing up”. It does not help that after the defrost cycle is over there is also a large whooshing sound caused by the reversing valve switching the system back into heating mode. Even though this process may look and sound like a system failure, it is a planned and necessary part of the heat pump heating process.
Preventive Maintenance: The Heat Pump Effect
Why would you call a technician to check out a unit that seems to be working well? You call them because these heat pumps are meant to be serviced. This is especially important for heat pumps. Heat pumps have secondary heaters that are essentially electric resistance heaters like the little portable ones at Wal-Mart. There is a difference, however. The ones at Wal-Mart are around a thousand watts. The back up heaters at your home can be up to 15,000 watts. A refrigerant leak can cause these supplementary heaters to run more and more in the winter. As the system loses its’ refrigerant charge the supplementary heaters carry more of the load. This degeneration of efficiency leads to electric bills that can reach several hundred dollars! PM service is essentially a very low-cost way to ensure you won’t be shell-shocked by your next electric bill.
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