A/C upgrade?

Our home has a Lennox HVAC system installed by the previous owner a little less than 10 years ago. The A/C unit has an SEER rating of approx. 11, which is low by current standards. How practical and cost-effective is it likely to be just to replace the condenser and compressor units and keep the existing plumbing? And what about adding a heat pump for winter heating (or pre-heating of the air before it gets to the furnace)? This is in W. Michigan, if that makes a difference.
Perce
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On Mon, 18 Jun 2012 18:18:30 -0400, "Percival P. Cassidy"

If there is nothing wrong with the A/C unit functioning and you just want to replace it to get a higher SEER rating; I would say that it is NOT at all cost effective.

Location makes a big difference. An air-source heat pump efficiency drops to that of electric resistance heating at around 37F. Actually, at around that outside temp, the heat pump switches to electric resistance heating.
If you are interested in saving $$$, concentrate on insulation and weather proofing.
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On 6/18/2012 5:39 PM, CRNG wrote:

that is assuming that the systems uses electric heat as a backup. Mine is a natural gas furnace that it switches over to when it decides it can't do it on heat pump anymore. It also depends on the size of the unit. We have one rental we purposely had the guy oversize the system (we were hoping to add on and finish the attic) and it will successfully heatpump all the way into the lower 20's.

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That's incorrect. While the heat pump efficiency drops as the temperature decreases, with a modern heat pump it's still well above that of resistance heating until the temp is in the low teens or single digits. The bigger problem is that with a reasonable size system you just can't get enough heat out of it at lower temps to make it practical for the amount of heat you need in colder climate. That's why it has to start using resistance heat as a supplement.

Not true with a new modern one.

Always a good place to start.
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On 6/18/2012 5:18 PM, Percival P. Cassidy wrote:

any modern heatpump/ac unit with a higher seer is gonna need a new lineset and A (or N) coil. Do it up right. Replace all the pieces.
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It definitely needs a new coil to be matched with the compressor. However as long as the existing lineset is in good shape, they can be re-used as long as they are properly flushed. If it's 25 years old and easy to replace, I would. If it's 10 years old and installed inside walls, etc that would make it difficult, then I'd consider re-using it. The cost of the copper tubing is only about $250.
I agree with the advice that suggests the payback time of a new, higher efficiency system is going to be long. How fast it pays back depends on the cost of electricity and how much the system is used. Also factor in rebates that may be available from utilities, states, etc. The time to have considered this was 2 years ago when there was a 30% fed tax credit. Given the area, I doubt the math will make it a viable option.
Heat pump is going to also depend on the cost of electricity and alternate fuel costs. Again, given the northern climate I doubt a heat pump system is going to work out economically. It would likely have to be dual fuel or ground water based and both of those drive the price up.
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Probably won't do much good, for your electric bill.
Most of what's for sale by contractors now days is "puron" which is not compatible with R-22.
You can save a pile of electric, by having the outdoor unit professionally cleaned. The tech should spray it with the hose, pour purple liquid stuff on, wait 3 to 5 minutes, rinse. Should be washed twice, or three. That will remove the dirt, and restore the efficiency.
Christopher A. Young Learn more about Jesus www.lds.org .
Our home has a Lennox HVAC system installed by the previous owner a little less than 10 years ago. The A/C unit has an SEER rating of approx. 11, which is low by current standards. How practical and cost-effective is it likely to be just to replace the condenser and compressor units and keep the existing plumbing? And what about adding a heat pump for winter heating (or pre-heating of the air before it gets to the furnace)? This is in W. Michigan, if that makes a difference.
Perce
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