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Why replace my 15 year old heat pump?
17 December 2005

Q. I am the owner of a single family house with a 15 year old heat pump. Recently the unit stopped defrosting. I had a service technician come to inspect the unit. He said the electronic board that controls the defrost cycle is not working, and must be replaced. The estimated cost is about $350. However, due to the advanced age of my heat pump, the service technician recommended replacing my entire unit - inside and outside. The cost of replacement is about $5,000.

Generally speaking, I love my current heat pump. It is very reliable and very economical. I have extremely low monthly utility bills and the unit does a good job in winter and summer. Which leads me to my two questions. Do heat pumps really need to be replace at such an early age? Everyone I talk to seems to say heat pumps generally only last about 10-12 years. Anything more and you are on borrowed time. Everyone tells me that the service technician is right - replace the unit, don't fix the part.

I don't get why a heat pump should need complete replacement after only 10-12 years-- in my case 15 years. It seems like you should be able to repair and fix the unit many times before you will ever match the cost of replacing it. I know many older furnaces would last for 30+ years. Our society seems to be a very "throw away" society these days.Wouldn't it be wise to invest money into repairing a heat pump, before replacing it?

Do you feel that both units should be replaced as a "matching set"? Or can you just replace one unit at a time? My outside unit is the one with the problem. The inside unit is fine. Although it is even older than the outside unit-- probably 20+ years old. But once again, everyone seems to tell me the same thing - replace both units. I don't seem to understand the logic behind replacing both units.

Photo by Bob McClure

A. Iím going to echo the advice of your service provider and the other wise folks with whom youíve consulted. I must tell you, however, that your 15 years old compressor/condenser that alerted to to its problem by looking like the unit in the photograph has done its job and doesnít owe anybody anything. It has served you well but itís time for it to go for a couple of reasons. Sure, it seemed to you to work well and operate at a level that did not weaken your bank account, but all things are relative.

Letís look at it in its 15 year time frame and compare it to what happens today. Heat pumps have a reputation for lasting from 8 to 12 years-- in my experience-- on average. Some last longer-- some less. Thatís because they do double duty- both heating and cooling. Those furnaces that you eye enviously lasting 30 years plus are only working less than half the time the heat pump does-- no A/C-- so proportionately the heat pumpís right up with them. When I see a heat pump working well at the age of yours I always say the good news is, itís still working and bad news is, itís still working. The older a heat pump is in todayís world the more electricity it will use to do its job.

There is a formula that is is used in the industry to calculate the energy in against the heating and cooling that comes out of it. It called the SEER rating and means seasonal energy efficiency rating. You see them written on the sides of the newer units and they are numbers that hover around 10 and up a bit. The SEER number indicates the amount of electricity that goes into the unit against the amount of heating or cooling capacity that comes out-- the higher the number the more efficient it is. Your 15 year old unit is probably 10 or less. As of January 23 2006-- next month-- every unit sold in the US will have to be at least SEER 13. Thatís pretty darn efficient and to do that the heat pump engineers had to go to a different coolant and had to redesign the units-- both inside and out. Thatís why both have to be replaced.

Pouring money into your old unit is not economical in the short or the long run in view of the new requirements. You could nurse your old soldier along with $350 here and $200 there for maybe a couple of years or so and then the technician will come out, look at the unit and deliver the bad news-- itís shot and thatís all there is to it. Now all the money you put into the older unit is money gone and youíre right at square one for the new unit. So go ahead and get on board with the replacement system and keep a sharp eye on your heating and cooling bills-- Iíll bet youíll be pleased.

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