Shopping for furnaces...confused!!


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Old 01-31-07, 09:35 AM
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Shopping for furnaces...confused!!

As the title reads, I am in the market for a new furnace and confused.

Some background. My house is brick, 2 story, from the 1920s in Pennsylvania. Its about 1200 square feet. I had the walls and attic insulated last year with blown-in cellulose. The windows arent the best but the house is very tight now. Will probably be buying new windows in the next year or so.The furnace is probably the age indicated on the concrete its set on...1948. A beast!! Some questions...

1) My home inspector highly recommended Rheem/Ruud. Does anyone out there have any issues with this company or recommend/not recommend them and why? If not, what do you recommend?

2) Last year I had two Trane companies quote me on 90% single-stage furnaces and calculate 60,000 btu both. This year, one Rheem company calculated 75,000 btus for a 90% 2-stage unit; another Rheem company calculated 75,000 btu for an 80% 1 stage and then 60,000 btu for a 90% 1 stage. Both said I was right on the border of the two sizes. I've read if you get a furnace thats too big that it actually wont be as efficient. Can anyone explain why the differences in furnace sizes? Does it have to do with brands? And generally, if you are on the border of 2 sizes, is it better to go down or up in size? I am so confused!

3)I've heard good things about 2-stage furnaces. However the second Rheem contractor says that in older, existing construction, where ductwork was installed after the house was built, and therefore not in ideal locations in the home, that 2 stage furnaces arent worth the extra money and actually dont work as they should, like in a newer constructed house. In fact, his company doesnt sell them because he said they only service old homes and they didnt find that the 2-stage furnaces heat as they should in the old homes. He said that the because the furnace isnt kicking on at 100%, the heat wasn't blowing strong enough to reach the extremeties of the house, and people were finding those rooms colder. bottom line, he said, if they arent happy with a product, they wont sell it. I was impressed that he wasn't trying to push something more expensive on me and to potentially save me money from buying something that wont work as its intended. Does this argument hold water? It makes sense to me, but I'm not an HVAC person. Can anyone comment on this argument?

Much thanks! I just would like the opinion of someone who is NOT trying to get my business and will tell it to me straight! Thanks
 
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Old 01-31-07, 12:49 PM
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Rheem/Rudd are good lines along with Trane/American Standard.

Are you ductwork going upstairs in the innerwalls? if so, I think you will be fine with 2 stage.

My uncle has it in his old 1930's home and has no issue with it.

As long the two stage furnace has a 2 stage t-stat, it will make the furnace run longer in 1st stage. I think also that you've updated the insulation, and soon to be windows, you will be fine with two stage.

My guts will lean towards the 60k for your home. I have 1300 sq ft, and my 60 keeps up just fine in our -15 degrees winter.
 
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Old 01-31-07, 01:09 PM
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thanks J.

I've also read that the Trane/American Standards were just as good. Glad you confirmed my research.

Yes my ductwork does go through the walls.

I'll make sure to check about the 2-stage t-stat (does that mean "thermostat"?).

Regarding the BTU size. I called the company and the man who quoted me said he was being conservative, and that since my home was on the cusp, he wanted to estimate higher. He did say he'd send the owner out to calculate precisely if I decide to go with them and we want to be sure. Just curious though- in general- if the size is a tad too big, how does that effect me, the effeciency and/or my fuel costs? Is the difference between a 60 and 75 alot? What would be the downside to getting a 75% in this case?

Also, Suprisingly the price given by the company that quoted me the 90% 2-stage was LESS than a 90% 1-stage price by the other company (both Rheem). So its not a matter of cost in this case, I just don't want to get something that wont work as it should.

Thanks for your input.
 
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Old 01-31-07, 01:20 PM
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ps

I just reread your post J,

When you asked "Are your ductwork going upstairs in the innerwalls?"
did you mean to ask if the ducts are run behind the walls? If so yes, the ducts were run behind the walls.

Or were you referring to whether the ducts were run on interior or exterior walls of the rooms?
In my downstairs, the heating vents were run through the floor (in kitchen and living room). The dining room vent is on the wall on a central (interior) wall.
Upstairs, there is a vent going up the steps (on an inner wall). I have 3 bedrooms. In two of the bedrooms (mine included), the vents are located on exterior walls; the third bedroom's heating vent is on an inner wall.

Would you think there would be issue with heating the upstairs rooms with the exterior wall vents with a 2-stage furnace?
 
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Old 01-31-07, 06:56 PM
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I was meaning if the main duct going upstairs was in the inner or outside wall. not the vent placement.

I know some older homes, the main supply duct are running up the outside wall, and has very little or no insulation, so the cold walls will cool down the ductwork alot.

As for BTU 60 vs 75 is not that much of a diffrenace, just on milder days it going to cycle a bit more.. If you were getting from 60k vs 120k, I'd be worried!
 
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Old 01-31-07, 06:59 PM
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two stage furnaces work great in all conditions granted that you wire in a two stage thermostat. i would have another load calculation done on the home, if you want to get the best you can look into a 90% , variable speed system, 2 stage. Otherwise get the standard 90%, i wouldnt go with an 80. Trane is a very reliable furnace and i have installed many of them. Rheem also makes a good furnace though i dont see enough around here to give u a good opinion. The biggest part of replacing a furnace is the installation, make sure that they take their time, check static pressure in the ductwork, make all necessary duct changes and set airflow correctly. its worth the extra few hundred dollars to get the job done right.
 
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Old 02-01-07, 06:54 AM
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[QUOTE=Jay11J;1118503]I was meaning if the main duct going upstairs was in the inner or outside wall. not the vent placement.
QUOTE]

I just checked the two bedrooms with vents on the outer walls; the ducts are run through the outer walls. The third bedroom, the duct is run through the center of the house. But like i said the walls are insulated. Still think the 2-stage would work ok?
 
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Old 02-01-07, 11:38 AM
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Yeah, it should work out well. Just make sure you get a two-stage t-stat so that way the furnace can run longer, and don't fall for the "Timer works just as well" pitch. It don't.. I did a test run on mine and cycles too often, and been a couple of times it ran in high stage for 1 min!
 
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Old 02-01-07, 12:21 PM
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t-stat means thermostat right?
 
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Old 02-01-07, 03:05 PM
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Yes, it does. Just a little shorthand to save time.
 
 

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