Venting Of A New "High Efficiency" Forced Hot Air Furnace ?

Hello:
Would appreciate any information on the following:
Will be replacing a very old gas, forced hot air furnace with a new "high-efficiency" type.
Have just read in the Audel's HVAC manuals that for a "high-efficiency" type of hot air furnace, you do not vent thru the chimney (or via a metal vent pipe that goes thru roof like we now have), but rather you vent via a PVC pipe thru the side of the house. It wasn't worded such that you might think that this is an an option, but rather that this is the (only) way to do it.
Has to do with the fact that the gas is not very hot from these types of furnaces, and the condensate would flow back and ruin the furnace, etc.
Is it the "only" way ?
Is there a "mid-efficiency" forced gas hot air furnace that would enable venting in the manner we now are doing it (thru the roof) ?
Sure don't want the expense of trying to configure a new vent thru the back side of the house !
If so, how would these "mid-efficiency" furnaces be designated: by SEER Number, or... ?
Any thoughts on this would be most appreciated.
Thanks, Bob
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If you live in an area that has high heat bills and want to really save then a condensing furnace is the way to go. You pretty much add 10 - 15% efficiency over non condensing. Non condensing are around 80-83% and condensing easily up to 94.5% on several makes. Vents can be run a specified distance to help in location of vent-exhaust. Everything has its drawbacks.
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Hello:
Would appreciate any information on the following:
Will be replacing a very old gas, forced hot air furnace with a new "high-efficiency" type.
Have just read in the Audel's HVAC manuals that for a "high-efficiency" type of hot air furnace, you do not vent thru the chimney (or via a metal vent pipe that goes thru roof like we now have), but rather you vent via a PVC pipe thru the side of the house. It wasn't worded such that you might think that this is an an option, but rather that this is the (only) way to do it.
Has to do with the fact that the gas is not very hot from these types of furnaces, and the condensate would flow back and ruin the furnace, etc.
Is it the "only" way ?
Is there a "mid-efficiency" forced gas hot air furnace that would enable venting in the manner we now are doing it (thru the roof) ?
Sure don't want the expense of trying to configure a new vent thru the back side of the house !
If so, how would these "mid-efficiency" furnaces be designated: by SEER Number, or... ?
Any thoughts on this would be most appreciated.
Thanks, Bob
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Hello:
Would appreciate any information on the following:
Will be replacing a very old gas, forced hot air furnace with a new "high-efficiency" type.
Have just read in the Audel's HVAC manuals that for a "high-efficiency" type of hot air furnace, you do not vent thru the chimney (or via a metal vent pipe that goes thru roof like we now have), but rather you vent via a PVC pipe thru the side of the house. It wasn't worded such that you might think that this is an an option, but rather that this is the (only) way to do it.
Has to do with the fact that the gas is not very hot from these types of furnaces, and the condensate would flow back and ruin the furnace, etc.
Is it the "only" way ?
Is there a "mid-efficiency" forced gas hot air furnace that would enable venting in the manner we now are doing it (thru the roof) ?
Sure don't want the expense of trying to configure a new vent thru the back side of the house !
If so, how would these "mid-efficiency" furnaces be designated: by SEER Number, or... ?
Any thoughts on this would be most appreciated.
Thanks, Bob
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I apologize for any multiple posts on the furnace venting question.
My OE is acting up, again.
Bob
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Go 94% or higher...go with the highest AFUE you can possibly afford.

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that
Its the only way to do it correctly, as all your new 90%+ units are set up that way.

Pretty much....I mean...you can do whatever you want, but running the intake and exhaust on the new units takes about an hour in most cases, and its not real difficult. Your installers know what and how to do this.

Nope...not unless you call 80% mid....we call mid 90% units, and all of them vent via PVC pipe.

back
AFUE. SEER is ONLY for AC HSPF is for the heat mode on a heat pump. In all cases, higher numbers mean less expense to run.

We use a concentric vent on all our new installs where the old unit is vented via B pipe like you have now. All it takes is a 4 inch hole in the side of the home, and the intake and exhaust are in the same opening, but you only see a round "cap" that is on the outside of the home. The center of the vent is the exhaust and the backside is the intake...under the home the pipe splits and the intake and the exhaust are in different pipes leading back to the unit. The vents are not overly expensive, and they are quick and easy for your installer to set up. Once they are in place, you just support the PVC every 5 feet or to your local code and its done. If you want to see pics of one, in action, let me know as we have several that we can either put on the website, or mail to you.

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You would not want anything less efficient then one that uses PVC. PVC is cheap and zero clearance. The guy who comes out to look at your old installation should have a way to do it. He is also going to have to route the condensate out of the house sometimes using a small pump and vinyl hose..... again no big deal.

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You can go through the chimney with an 80% eff. non-condensing furnace. With the high eff. you not only need to go through the side of the house but you'll also need a condensate pump and a means to get the condensate to an area where it can be drained----I use my washing machine drain. If you go through the side of the house and live in an area where you get a lot of snow be sure that the vents are high enough off the ground so that there is no chance of snow blockage. In the long run, there is a measurable cost saving going with the higher eff. furnace. MLD
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route
According to http://hem.dis.anl.gov/eehem/94/941108.html the condensation is supposed to run back to the furnace. :-/
I'm learning myself, and I don't quite understand why it wouldn't be better to keep the condensation out of the furnace.
The only thing I can come up with so far is that it's supposed to run back in to be heated enough to evaporate and be expelled as a gas instead of pooling in the exhaust pipe somewhere and restricting the airflow. But wouldn't a condensate drain work, and be a better idea, like you suggest above?
We have a pulse furnace at one of the homes where I work. I have no idea why anyone would want a pulse-jet honking away like that in their basement. It is quite annoying... the first time I kicked the furnace on I shut it back off because I thought it was malfunctioning.
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OK, I should have kept reading... it does say the condensate needs to be drained. sheesh! I was wondering why one would want water boiling off in the heat exchanger... what a waste of energy!
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Well, it condenses out in the 2nd exchanger, and there are at least 3 places on most units to remove this. You would be amazed at how many installers dont hook the lines up right and how much trouble such a little thing causes.

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