Choosing Furnace Efficiency

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On Wed, 04 Dec 2013 18:26:45 -0600, Big Giant Head

other almost trouble free. The old silicon carbide are the crappy ones. Silicon Nitride is the good stuff.
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On Wednesday, December 4, 2013 7:26:45 PM UTC-5, Big Giant Head wrote:

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?
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snipped-for-privacy@optonline.net wrote:

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 may just say screw it and get a simple 80% and call it a day. Not doing new air at this time.
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On Thursday, December 5, 2013 12:30:02 PM UTC-5, Big Giant Head wrote:

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.

What price differences are you seeing between 80 and 93%? Factor in any tax credits, rebates from utilities, etc?
Not doing

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.
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Maybe it's a case of CYA. They're offering 10 years parts + 10 years labor on the simple furnace. 15 / 15 on the fancy 80% variable speed. HX is 20 on both. They promise 2 hr response time day or night and if they can't fix it in 24 hrs they pay the hotel. A+ on BBB & Angie's list award winning so they probably do have good service (not that I verified these assertions but I'll take their word).
Carrier / Payne dealer offers only 5 years parts + 1 year labor. 20 years HX.
I don't know what part of that stems from the mfg and what part is from the dealer. Does Lennox have better warranty?
Wish I could get the long warranty on the fancy machine; it would make me feel better but I presume if I insisted on it with Lennox he'd probably say you're on your own after a minimal warranty. Or at the very least exclude ice buildup! I would, if I had his concerns.

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 efficency of course.

It's under the furnace so it can stay put. It should probably get a little cleaning. It would still be logical to replace the whole thing I know. It's really mostly about not having to think about that. I can barely decide on a furnace.
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Big Giant Head wrote:

What is your requirement for furnace size? It has to be properly sized. Over or undersized furnace is not a good thing. Proper, right sized one gives highest efficiency. What is the size of old one? I am good with Carrier always because Carrier parts are very easy to get. They can't fix it in 24 hours mean lack of needed parts not serious break down. Furnace is not really complex electric/electronic/mechanical device.
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The current 80% Bryant is 90,000 BTU/H input. I'm going to presume that's the right size unless someone tells me otherwise. Obviously, it could absolutely be wrong all these years but I've never noticed it not keeping up on the coldest days nor during normally cold winter days does it have extremely short cycles. Lennox guy did walk around and see the place, count vents, and so forth but never said oh, you should be at 70K so I'm guessing that was a write-o. I didn't notice it until after he'd left. If I do talk to him again that will be the first question.
Carrier - Payne guy just went with the 90K but then again I was asking about replacing what was there. Alas, his paper work doesn't mention model numbers.

I've repaired the current unit over the years. Inducer board, gas valve, inducer motor. But aren't new ones more complex with expensive microprocessor boards, and trouble codes, especially the HE ones?
Seriously thinking of pulling off those parts on the old one when it goes. Either to eBay them or just to keep for sentimental value since I put them in.
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wrote:

BTU rating to be optimal for our house - the low flame output of the dual stage I ended up buying is pretty close to "right-sized" - the smallest I could buy other than an R/V furnace.
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On 12/5/2013 9:28 PM, Big Giant Head wrote:

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.
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Ed Pawlowski wrote:

I had my old 80% efficiency Carrier(130K BTU) to 96% 100K BTU 2 stage one for 4 grand minus wiring and thermostat. I hooked it up and installed wireless thermostat, CO detector myself. Installer did all the rest to my 100% satisfaction. Passed inspection. Actually it is season for demand so price seems steep.
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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.
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On Friday, December 6, 2013 3:29:06 PM UTC-5, snipped-for-privacy@snyder.on.ca wrote:
entional 90,000 BTU/H Carrier $2450. >> Likewise but branded Payne $2250. >

00. >> 80% 70.000 Variable $3715. >> >> The latter is a lot for non high ef ficiency (which he didn't offer). >> >> I could not actually accept the Len nox bids as is since it says 70,000 >> but maybe that's just an writing err or. If we stay at 80% and assume the >> 90,000 is fine and decent duty cycl es even in below zero weather, then we >> need the same size. Dropping a no tch if we go higher efficiency of >> course. > >Assuming you are 80% that m akes 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 ins talled furnaces around here are at least 50% oversized - 30 to 40 year old houses.. What I installed is a 35/50kbtu, replacing a 75kbtu originally ins talled. 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.
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snipped-for-privacy@optonline.net wrote:

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.
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wrote:

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.
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On 12/7/2013 10:55 AM, snipped-for-privacy@snyder.on.ca wrote:

I think a bit over sized isn't good. In the case of my drafty trailer, I can always light a couple stove burners if the furnace isn't keeping up.
Works out, OK. I went from 80k to 70k when I replaced, and the 70k does fine. Of course, some cellulose in the ceiling helps, a lot.
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On Sat, 07 Dec 2013 11:22:07 -0500, Stormin Mormon

house in Ontario.
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On Sat, 07 Dec 2013 13:28:05 -0500, snipped-for-privacy@snyder.on.ca wrote:

Your house is a *tiny* two-story (very little ceiling square footage). It's more like a small townhouse. Of course it has an apartment-sized furnace.
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snipped-for-privacy@attt.bizz wrote:

I don't believe what he's saying. I used to live in Toronto(Scarboro) unless his house is match box sized house. LOL!
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wrote:

He said recently. IIRC it's around 1200ft^2, two story. Yes, pretty small. I lived in Burlington VT (somewhat North of ON, where he lives), in a ~1700ft^2 Cape Cod (a pretty efficient design). The furnace was 150KBTU and in the coldest weather it was constantly running.
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wrote:

basement. Forty years old - updated windows and insulation.
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