On Thursday, December 5, 2013 12:30:02 PM UTC-5, Big Giant Head wrote:
wrote:



On Wednesday, December 4, 2013 7:26:45 PM UTC-5, Big Giant Head wrote:

BTW, should I even ask about replacing the HX or is that completely



ridiculous on a 26 year old unit?



I would say it's ridiculous, if one is even still available.

Have you looked at tax credits, utility rebates, etc available

that reduce the cost of a new high-eff system? Those can make

a high eff one cost the same or less than a 80% efficient one.

Calculated how much a year you will save in gas and electric?

AC involved too? How much you will save per year with a 14 SEER

instead of a 26 year old that may be running at 8?





Hey, I had a Lennox dealer out last night and he strongly discouraged a HE

because the machine is going in an interior closet and the PVC pipe(s)

would have to pass through about 3-4 ft of unheated attic crawl space.

Said the condensation could freeze up. He was pushing an 80% but with

variable valve and DC variable blower. The Carrier / Payne dealer did not

have any issue with with the piping situation.



I'd say the Lennox guy is BS. I just checked a Rheem installation
manual and it says that the pipe needs to be covered in 1" of
insulation if it's run through unheated spaces where below
freezing temps are expected. And that if water could collect,
it should have heat tape applied. I don't know how the latter
could occur, given that the pipe has to slope downward, back
to the furnace. Given that the colder it gets, the more the
furnace runs, it's hard to see how it's going to freeze up
and block the vent pipes if you put some decent insulation
on them.

Around here, nyc area huge numbers of houses have furnaces
in the attic with 4 ft+ pipe runs and I haven't heard
of any problems. Of course if your attic gets down to 0,
that might present a problem. But if it is a problem in
your area, you would think all the installers would be telling
you about it. The alternative is you might have a contractor
that would rather do a quick switch install, instead of having
to run the vent pipes.



I may just say screw it and get a simple 80% and call it a day.

What price differences are you seeing between 80 and 93%?
Factor in any tax credits, rebates from utilities, etc?


Not doing

new air at this time.

I guess that's an option if they can do the job without
removing the existing evaporator. If they can't and have to
evacuate, open, purge, recharge, etc then given all that cost,
with a 25 year old AC, going to new AC at the same time would
seem a more sensible path to me.