View Full Version : Replace AC with AC or heat pump?

Ron Jones near Indy
06-04-2009, 10:54 PM
My AC unit is most likely on it's last legs. It's about 12 years old (Janitrol) and uses freon. I want to be ready when it gives up and quits. We have an 8 year old 92% (IIRC) efficient natural gas forced air furnace (Lennox in good condition). When it's time to replace the AC would it be wise to go with another AC or change to an air to air heat pump using the furnace as the back up. Any advise from the vast knowledge of the Creek is most welcome! Indy summers usually get to the high 80s or low 90s and very humid. The winters may go subzero for a few days; maybe more that once a season. I believe a heat pump will be about 1.5 times the $ of CA. Suggestions?

Tom Godley
06-04-2009, 11:17 PM
Heat pumps have come a long way -- I believe if you do some research you will find that they are the way to go vs a straight AC unit

The most efficient are the two stage units -- but you can only go that route with a change in the blower - that would require a change in the existing furnace. That may not be worth the expense.

I would ask if your are happy with the comfort of the current system in both heat and A/C. -- The multi stage/ variable speed furnace blowers are not only efficient they provide great comfort plus the two stage A/C units are able to run on low speed when it is humid outside but not overly hot -- this allows them to remove water from the air with out over cooling

Jim Becker
06-04-2009, 11:33 PM
Heat pumps can be very efficient with current models, proper insulation and in areas where your coldest days don't typically drop below the 30s most of the time in the winter. Tom's advise and comments are really good.

Jeffrey Makiel
06-05-2009, 7:54 AM
A couple more thoughts...

- The cost of electricity in your area can be a real killer versus natural gas. For example, residential electricity in New Jersery is a whopping 17 cents per kWhr. Therefore, heating with electricity can be quite expensive even if the heat pump is extremely efficient.

- Heat pumps for heating become less efficient as the temps outside get cooler. They have gotten better, but the decline is still there. This must be considered if your winters are cold as I'm guessing they are.

- Compressor life will be reduced since the unit will run much more to provide both heating and cooling needs. The overall life of the unit will be shorter. Therefore, the return on your investment (efficiency wise) may not ever be realized if the compressor quits in 8 to 10 years (typical warranty period).

-Jeff :)

Tom Godley
06-05-2009, 8:20 AM
You are using electricity to run the equipment -- but the cost to run a heat pump is not like the cost of running electric resistance heat. You can figure this all out when you look at the heat efficiency rating of each of the equipment set ups.

Modern heat pumps are more cost efficient than natural gas units at temperatures that would surprise - this is especially true with the new inverter drive systems.

The length of service of A/C equipment is such a strange thing - my neighbor just had to replace a top of the line Trane that was just out of the total warranty period and just used for A/C and I have a low end Goodman HP at a rental that Moses used on the Ark - still going strong. There does not seem to be a lot of correlation -- although it would seem that the more used heat pump should have a lower total year life.

Michael Roland
06-05-2009, 9:55 AM
A couple more thoughts...

- The cost of electricity in your area can be a real killer versus natural gas.

There is the option of going with a dual fuel heat pump.

Lee Schierer
06-05-2009, 12:21 PM
If you have your own water source or a good sized piece of land, a geothermal or ground source heat pump will work quite well in Indiana. I installed a new haet/AC two stage variable speed fan unit last summer. It cooled my house for 3 months witht eh same KW use as several fans and a dehumidifier and it heated the house last winter using less power and water than the prvious unit. I heated and cooled my 2200 sqft for $139 per month with no other utility bills.