On Sat, 07 Dec 2013 07:55:31 -0700, Tony Hwang
wrote:

wrote:
On Friday, December 6, 2013 3:29:06 PM UTC-5, wrote:
On Fri, 06 Dec 2013 09:03:51 -0500, Ed Pawlowski wrote: On 12/5/2013 9:28 PM, Big Giant Head wrote: Carrier guy: 80% Conventional 90,000 BTU/H Carrier $2450. Likewise but branded Payne $2250. 80% 2-stage 90,000 BTU/H Carrier $2850. 95% 80,000 BTU/H Carrier $3250. Payne $3050. Lennox Guy: 80% 70,000 Conventional $2400. 80% 70.000 Variable $3715. The latter is a lot for non high efficiency (which he didn't offer). I could not actually accept the Lennox bids as is since it says 70,000 but maybe that's just an writing error. If we stay at 80% and assume the 90,000 is fine and decent duty cycles even in below zero weather, then we need the same size. Dropping a notch if we go higher efficiency of course. Assuming you are 80% that makes sense, but are you? I'd ask the guy why he is quoting a smaller unit. It does seem odd that he would quote that much smaller. Over half the installed furnaces aroun
d here are at least 50% oversized - 30 to 40 year old houses.. What I installed is a 35/50kbtu, replacing a 75kbtu originally installed. Just about every house on the street had the same original furnace, wheather 2 storey, bungalow, or split level from 2000 to 4500 sq ft.

One advantage to having it somewhat oversized is that you can get
fast recovery from setback. If you're away for a few days, have it
set low, when you get home you can have the house warmed up in less time.
You obviously don't want it way oversized, so that it's short cycling,
but I'd rather err on the side of a bit too big than the other way around.
I replaced a 25 year old 150K btu with 120K 93%. In retrospect, based
on the run times, I could easily have used a 90K too, but I'm happy
with the faster heat up times.

HI,
It better be 2 stage one, ours mostly run on 1st stage, this morning it
is -31C outside with ice crystals in the air, furnace is going full
blast coming back up from set back during the night.
Oversized furnaces suffer in the efficiency department. Undersized
furnaces just take a little longer to warm up a house, unless the wind
blows straight through like Stormy's trailer. Furnace efficiency
doesn't mean anything at all in a situation like that anyway.