On Mon, 18 Jun 2012 21:38:26 -0400, Duesenberg wrote:

On 6/18/2012 8:17 PM, Oren wrote:
On Mon, 18 Jun 2012 18:18:30 -0400, "Percival P. Cassidy"
wrote:

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

I cannot speak to the heat pump. In order to match the SEER rating for
the compressor and the furnace, they should both be replaced at the
same time... a matching set. It's what I had done after 12 years of an
older 10 SEER rated unit.

YMMV.


I have a 14 year old 10 seer that improved with a new variable speed
blower and recharged refridgerant and hosing out the colling fins of all
the dust and bugs.

I'm curious if you have any numbers or data or something to share with
me/us about upgrading from a 12 year old 10 seer to what you have now.

I considered upgrading to a 14 or 14.5 seer but quite frankly didn't see
a payoff. The prices of the units rose when the governments had rebates
and now that those rebates are gone, magically the price of those units
fell and that soured me on replaced my a/c unit....
The operating cost difference between a 10 seer and a 13 seer is
about 3 percent.

A 2.5 ton 10 seer unit will give you about 3000 BTU of cooling for
3000 watts A 13 seer unit will give you the same 3000 BTU for roughly
2307 watts. The savings between the 2 if the AC runs 18 hours a day is
12.4 Kw Hours (3000-2307x18/1000).

If electricity costs $0.11 per kWh that is $1.36 per day
Going to a 14 seer from a 13 saves another $0.31, more or less.

What's the cost of a new 13 or 14 seer unit, installed, with a service
contract (you do NOT want a leading edge technology system without
it)?

Let's just grab $3000 out of the hat, and say your A/C unit runs the
equivalent of 180 days a year, 18 hours a day. Don't know where you
live in Western Michigan, or what your daily average mean temps are
etc - so again ot's just a number pulled out of the hat. If you went
from 10 seer to 14 seer and saved $1.67 per day in power used, the
savings would take 1796 operating days, or with out assumption og 180
standard days a year, 10 full years to pay for itself.

Southwestern Ontario and Western Michigan may be quite similar
climate-wize - and if so, mine seldom runs more than 9 hours a day,
and an average year perhaps 30 days - for an average much closer to 21
9 hour days. My savings going to a 14 seer would therefore be a whole
lot closer to $0.85 a day, for 21 days a year -or Less than $21 per
year. Say I'm off by almost 50%- I run the system for a whole month,
every day, 9 hours a day, for a $30 per year savings and that is still
100 years to pay for the high seer unit!!!

And my bet is you won't replace your system for $3000 either.