1-stage vs. 2-stage


Old 08-24-05, 03:04 PM
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1-stage vs. 2-stage

I live in NJ. Is a 2-stage furnace worth lowering the efficiency? I can either go with a 80% 2-stage or a 90% 1-stage based on price. (I am comfortable with either installer) I see that 2-stage furnaces claim to have some efficieny benefits over single stage, but I can't believe it would amount to 10%.

Thanks in advance.

Last edited by new_homeowner; 08-24-05 at 04:30 PM.
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Old 08-24-05, 04:04 PM
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1-stage vs. 2-stage

I replaced my old furnace a month ago. I got an 80% 2 stage with a variable speed DC fan. I am in Minnesota.

I don't know about the 2 stage burner, but the variable speed fan made my old air conditioning work much better, is more comfortable (humidity-wise) and is much quieter. It also uses less power, so I can keep it on to circulate two levels.

I think the 2 stage comes with the variable speed fan versions of most brands. I am very happy and sold on a variable speed fan.

Old 08-24-05, 07:42 PM
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You can get 2-stage in both 80 and 90%

Dick got the 80 cuz the way his home is laid out, the PVC venting would not work out with out being an issue.. Where my home I don't have the issues, and have a Trane 90% that is vented out the back of the home.

The 2-stage is very well worth the extra money.. You get the best comfort in your home.. It's almost like hot water heat. You're getting a steady heat at a lower temp, and longer time.

With longer run time, the rooms will be more even in temp.. I live in an older home, and last winter when we were dipping down -20's at night, all the room was warm.. No hot or cold spots.

If you go with 2-stage, best to go with the 2-stage t-stat for longer run time vs using a timer on the board.

FYI, the 80% burners are going to have a louder rumble sound vs a sealed burners on a 90%. so you will hear the burners on the 80%

As dick says, you get better cooling on the variable speed blower, and quiet.
Old 08-24-05, 07:58 PM
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need answers on converting my furnace.

I am a licensed plumber. I understand all of the local codes for venting and gas piping and gas sizing. I am currently on oil heat and looking answers on converting over to an LP 90% furnace. My home is 1,950 sq. ft. The current oil furnace has 106,250 btu. input rating. I don't know if LP and oil will require a different btu. rating when I am shopping for my new furnace and I plan on doing the installation myself. If anyone can help me to learn how to size the proper furnace for my home I would greatly appreciate it.
Old 08-24-05, 08:26 PM
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Reply has been moved to a new thread.

Last edited by Jay11J; 08-25-05 at 07:02 AM. Reason: Moved posting.
Old 08-25-05, 05:40 AM
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Sorry, didn't realize I was in someone else's post. I did start a new thread. Thanks.
Old 08-25-05, 05:42 AM
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I am assuming the 80% 2 stage furnace has a variable speed blower.

This is my take. The 80% will save you $$ when it has to operate in only the 1st stage. With that said, these furnaces with var speed blowers are more about comfort.

These are the benefits.

1.Better air quality if equipped with a good whole house 5" pleated filter cabinet like Honeywell,AprilAire

2.quieter than a 90% sgl stage but not quieter than a 90+% 2 stage with var speed blower

3. Better dehumidification in AC mode if equipped with matching AC condensor and coil.

4.var speed blowers are less expensive to operate than conventional blowers

5.better room to room comfort and temperature constancy-not the big swings in temp that are normally associated with your single stage furnaces.

Still with the expected rise in nat gas prices, I would look at a 90% 2 stage with var speed.

My opinion.
Old 09-10-05, 10:32 PM
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Originally Posted by TigerDunes
The 80% will save you $$ when it has to operate in only the 1st stage.
If you mean "save $$" compared to the second stage operating, that is not correct. Most two stage furnaces are actually slightly less energy efficient on the low stage, because the burners were designed for operation on the high stage.

The advantages of a two stage unit are that on the first stage, the unit will be quieter, the temperature will be more constant, and the unit will not short cycle. The variable speed blower found on many two stage units provides additional benefits.

But there is no higher efficiency or $$ savings when operating on the first stage; it is only a comfort benefit.
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