Choosing Furnace Efficiency

You've met him, have you?? A genius at his feild of expertise - setting up condominium plans. Not terribly bright about a lot of other things.

And I bet in comparison to either of us you are dumber than a sack of rocks.

Reply to
clare
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2 different kinds of hot plate ignitors. One is pure trouble - the other almost trouble free. The old silicon carbide are the crappy ones. Silicon Nitride is the good stuff.
Reply to
clare

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?

Reply to
trader4

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.

Reply to
Big Giant Head

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.

Reply to
trader4

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.

Reply to
Big Giant Head

Hi, 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.

Reply to
Tony Hwang

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.

Reply to
Big Giant Head

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.

Reply to
Ed Pawlowski

Hmmm, 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.

Reply to
Tony Hwang

The dealer that sold me my furnace offered a fantastic warrantee on the system and installation - then promptly went T.U. less than a year later. The warranty from the manufacturer, without the dealer to back me up, ended up being far less valuable. "pay for the repairs at the going rate, submit for warranty consideration, and we may or may not pay all or a fraction of the repair cost" that was Tempstar.

Reply to
clare

Nobody offered a single stage residential furnace with a low enough 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.

Reply to
clare

Over half the installed 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 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.
Reply to
clare

n 12/5/2013 9:28 PM, Big Giant Head wrote: > >> Carrier guy: >> >> 80% Conv entional 90,000 BTU/H Carrier $2450. >> Likewise but branded Payne $2250. >

$3250. >> Payne $3050. >> >> Lennox Guy: >> >> 80% 70,000 Conventional $24

  1. >> 80% 70.000 Variable 15. >> >> 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.

Reply to
trader4

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.

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.

Reply to
Tony Hwang

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.

Reply to
clare

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.

Reply to
Stormin Mormon

Excellent points but I'm pretty sure the existing furnace has a cracked heat exchanger and replacement is mandatory immediately. (See seperate thread about that.)

To check for cracks in the heat exchanger , close off all heat registers. Run furnace and when blower starts watch the burner flame. If there is a crack the air pressure will blow against the flame and you can see that movement. That is how the gas utility checks it. WW

But since you asked, no the house is terribly inefficient. Built in 1957 with metal window frames, no insulation in the walls, concrete slab floor. It does seem laughable to have a super efficient furnace in combination with those things and if one were choosing what to put money into, it would be these other things first.

On the other hand, all of those things mean more heat is required and a super efficent furnace is going to make more heat with less money. If rebate and tax credit pay for most of the difference then maybe this is the way to go.

Reply to
WW

That's still almost TWICE the size of the furnace in my 2 stoey house in Ontario.

Reply to
clare

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.

Reply to
krw

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