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Red Seal Electrician
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I've never heard of a (US) jurisdiction that banned homeowners from doing their own work, whether it be electrical, plumbing, framing or HVAC on their own home.
Good thing re-checked; there is now a means for a homeowner to pull a gas permit. (BC, Canada here.) I still can't get piped gas to my house though... haha.
 

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...i have a bunch of celulose blow in in the attic and about 6" XPS and Roxul in the walls. and the basement has insulation on the walls.

...the conditioned part of the house is about 1100sf.

Sounds kind of like a bungalow. Is there a 2nd floor? Do you have central a/c?
 

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Discussion Starter #23
Sounds kind of like a bungalow. Is there a 2nd floor? Do you have central a/c?
i am not "up" on the types of homes, but i believe mine is a bungalow. it is basicly a shoebox with a 1/2 below grade basement, no 2nd floor. basement is not directly conditioned, but in the dead of winter it only gets down to about 60'ish.

yes, a/c
 

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Discussion Starter #25
You're confusing btu input and output.

Now, for a 1000 sq ft space in the northeast to need 58k output, has to be poorly insulated.

So you may need a smaller furnace after all.

You have some misconceptions about condensing furnaces:

1. They don't produce condensation in ducts - condensate is produced in the secondary heat exchanger and drains off through pipes.

If you don't have a floor drain, need condensate pump which is no big deal. Only if the furnace is in an unconditioned space would i go 80%.

If you have a/c now, should be very easy to drain a condensing furnace.

2. They don't have extra mechanical/electrical parts to go bad, usually they share the same circuit board and controls. If you want the lowest repair costs, stay with single stage.

As far as roi goes, natural gas is extremely cheap now and but could way up. I would not make a 20 year decision based on today's prices.

High efficiency furnaces have advantages beyond saving fuel...

Thanks to sealed combustion, there's no open flame in the house, the furnace doesn't dry out the house due to using indoor air, and there's less burner/inducer noise.

Mids are pretty much obsolete in cold climates, they haven't been available in canada for 10 years.

In the states they're still available because condensing makes no sense in a/c dominant climates. When the heating season is 5 to 6 months, it's crazy to put in an 80%'er.

I do recommend calling a pro because there's much to screw up. The gas and venting work definitely should be done by someone licensed unless you know how to do that aspect of the job safely.

Sheet metal work is very difficult for the novice, it takes a lot of practice to get good. I'm really bad at it.
the house was poorly insulated. now it is pretty good insulated. so yes, a smaller unit would heat the house just fine.

i have a floor drain basicly right there.

tough question = repair costs, how much more, % wise, could i be looking at ?

sealer combustion = now that would be of good benifit to me. my house, while i took efforts to seal it, it is not sealed. so not having the furnace pulling in cold air would add to the efficiency. thanx :smile: . now, the vents for the firebox = pvc in and out, and they go out a wall. correct ? i could do that easy. gas work, psst, thats easy.

sheet metal work. i do know that is a "skill". but i would want to keep that to an absolute minimum = basicly whatever adaptor i would need to make to attach my current 20" plenum to the new unit.
 

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tough question = repair costs, how much more, % wise, could i be looking at ?
High efficiency is the same as mid but burners are at the top, has secondary heat exchanger just above blower, plastic inducer assembly and condensate handling components.

Provided the secondary doesn't fail due to defect, repair costs are very similar.

One consideration is that the existing chimney liner may be too small for the water-heater once furnace is removed.

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You should do a load calculation to see how much heat is really required.

You have a 2-ton a/c.
 

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Discussion Starter #29
poop, i got furnace on the brain, so i forgot about the HWH venting. i think i should just stick with a direct replacement 80%. really all i am after is reliability.
 

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Water heater venting may be no big deal - your existing venting may be just fine.
Some replace with power vent rather than put in a smaller chimney liner if it's too large.

Putting a 80% is stupid in chicago is stupid, frankly. Waste of gas, less safe with open flame, more noise.

If you don't have a masonary chimney without a liner, keep in mind you should have a liner for mid efficiency furnace anyway.
 

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Discussion Starter #31
Water heater venting may be no big deal - your existing venting may be just fine.
Some replace with power vent rather than put in a smaller chimney liner if it's too large.

Putting a 80% is stupid in chicago is stupid, frankly. Waste of gas, less safe with open flame, more noise.

If you don't have a masonary chimney without a liner, keep in mind you should have a liner for mid efficiency furnace anyway.
4" vent for both furnace and hwh = that same one. in brick

my gas bill isn't high. open flame isn't an issue, nor is noise.

is 80% mid ?
 

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4" vent for both furnace and hwh = that same one. in brick

my gas bill isn't high. open flame isn't an issue, nor is noise.

is 80% mid ?
I think you need to do more homework (learn what equipment is out there, what's involved in finding the right match for the house/ductwork, what's required for proper commissioning, venting codes, etc) before undertaking a project like this.

It's not like replacing a dishwasher or water tank.

Yes, your gas bills are low now because gas is very cheap at this point. Can't predict the future and it may spike.

Not to mention, if you have a masonry chimney, it may need repairs in the future which could be far more than the price premium for high efficiency.

Going cheap now will not pay off. A builder's goodman btw may not be terribly reliable long term - one of if not the cheapest makes out there.
 
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please forgive my ignorance on terms. but the "plenum", that is the flats of both the a/c box bottom and the furnace flat top, where they meet up ?



The plenum is the term for the metal box at the top of the furnace where the AC evaporator coil resides. BTW you never mentioned AC. Your coil may not fit inside the new one. The project just got real complicated. The inside and outside parts of a central AC must be balanced to work. Finding a coil that will work may become a serious problem.



While you may be able to sneak in an install of an ordered furnace from out of state you will not be able to buy any AC Freon or most parts.


This may not be the project you expected. You may well be better fixing the one you have if it is less than 20 years old or calling in a pro.
 

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The plenum is the term for the metal box at the top of the furnace where the AC evaporator coil resides. BTW you never mentioned AC. Your coil may not fit inside the new one. The project just got real complicated. The inside and outside parts of a central AC must be balanced to work. Finding a coil that will work may become a serious problem.
Normally the existing plenum and coil can be left alone and a transition built.

New furnace is normally shorter than existing.
 

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Discussion Starter #38 (Edited)
my plan, once i get the unit i need. disconnect the the plenum(and all the other stuff). then put straps on it to pull it up to the joists just a little. slide the old unit out. make whatever adaptor to make up for size difference, should be nothing more than a pice of sheetmetal. slide the new unit in and reconnect everything.

what i don't know = will the blower in the new unit be enough for the a/c ?
 

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I think its the blower and the transformer you need to check. They may all be compatible now but in the past they were not.
 
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