Would Infinity Solve Cold Basement/Allergies Better than Performance?

[baffled]

Hi - I'm replacing my original, 23 yr old Carrier Weathermaker SX 58SX060 gas furnace that's starting to develop old age problems.

Recent yrly gas bills avg $600; I keep main floor of house 68 to 70 in winter (brrr!) w/ set-back for weekdays & nights. House is built into a hill w/ finished walk-out basement which is 4 to 5 degrees colder than upstairs.

Due to finished basement, house totals +/- 2,400 sq. ft. HVAC-Man recommends bumping up to 80,000 BTU due to size & house aging. (23 is aging?)

Looking for advice between Carrier Performance 93 (2 stage) and Infinity 96 (2 stage variable.) Carrier HVAC-Man says Infinity is about 94% in real life, so makes little diff in gas bill. Since both are 2 stage, one main diff is Perf's fan runs only when furnace is on, where Infinity's fan can be run constantly on much cheaper DC current.

Issue 1: I use basement's 2 bedrms (east-facing windows) as a computer/ guest room & a workout room. They are uncomfortably cold in so. Wis winters (tho nice in summers!) I run an electric oil-filled register when I'm down there, but is slow to heat, doesn't warm far from unit & pops electric bill!

Issue 2: Allergies all winter (dust, etc.?) - I plan to add their air cleaner to either furnace.

Questions: Any idea if Infinity would resolve either/both issues noticeably more than Performance?

Any way to guess as to how many degrees basement may warm up if the Infinity's fan is blowing all the time - and would it be much different than the Perf?

Would Inf's continuous fan make a noticeable difference in dust, etc., levels over Perf's fan when on?

Anything else I should be considering?

Sorry this got so long, trying to give a complete picture. Hope it's the only furnace I ever buy, so want to do it right!

Thanks for any insights! Barb

[dash]

Fan on will improve filtration and temoerature differences betwen rooms,but may not solve the problems with temperature differences.


It may well take a Manual J load calc and Manual D duct calc ,and a redesign of your duct system.The contractor on site should be able to let you know.


Now it's true the VS DC motor uses a lot less wattage,but that's at lower ESP(External Static Pressure,which is resistance of the ducts,etc.),but at higher ESP's it can use more.The difference is the VS at higher ESP's will deliver the required air flow,where a standard motor can't.


They need to test the ESP,and add the resistance of that new filter ,to determine what the wattage will be.Now with the Infinity, you can run the fan on the off cycle, at low or medium keep the wattage lower,user controled feature.

[baffled]

Thanks, Dash. Wow, this went over my head fast!

What I was told: running the Perf fan continuously would cost about $300 per year in electricity, the Inf (on D/C) about $30. It sounds like you're saying that was more sales talk than truth, without them looking closer.

If their claim was close, if I run the fan all the time, it'd be the Inf.; if not, the Perf. Well, that's what I don't know - DO I want to run it continuously, from a comfort standpoint?

If I understand what you mean by redesigning ducts, since it's not part of a remodel/addition, just a furnace replacement, changing ducts/ripping out drywall would be way too $$$ for what I'd benefit.

Just the addition of the air cleaner should make a good dust difference over not having one (like now.)

If Inf makes a 1* diff or a tiny dust level change, I should pick the Perf. & put the savings into bumping the temp up a bit and buying some kleenex, cuz I'd need it either way.

If Inf makes a 3* diff or cuts the runny nose thing way down, it'd be worth springing for it.

And that's the great unknown! Are those 2 Manual calcs the only real way to answer this? Thanks again for your help, Dash!

Barb

[dash]

The calcs ,are needed to know what airflow(cfms) is required per room and what size duct.They can also measure the airflow that each room is getting to aid in redesigning.


How many degrees is the room(s) in question off from the rest of the home,and how far from the furnace are they?

BTW the Infinity handles ,other comfort issues very well.Like your humidifier,and dehumidifing during cooling.

I'm not saying it's just Sales talk,keep in mind if you select low speed in the off cycle,the air flow,will be more lower as well as the static,however this means less air is being circulated,so it may not even out temperatures as well.Maybe Med speed would be low stati as well.

Filters do a better job with less airflow so filtration should be fine.


Dust is interesting,many particles, "fall " from the air before they get to the return duct,so those can't be eliminated.Less stuff in you equipment and the air you breath is the reason for better filters,dust improvement is usually less than you might expect.

[RoBoTeq]

The differences in the costs of operating either of the style blower motors may be exagerated, but definately not just sales talk. The VS motor is going to be less expensive to operate.

As for the varying temperatre issues, this is a ducting issue and not an equipment issues. You are always going to have different loads and losses between different levels of a home at different times.

If your supply regesters in your basement level are not down low on the wall, you will never get the living area of the basement as warm as the upper levels of the home.

If you want the temperatures of rooms to be closer to each other, cut down the amount of air going to the warmest rooms till a balance is reached.

[baffled]

Wow, that was a quick reply! Main floor is 67/69 when I'm home/awake, 61/63 at nite/at work. Basement bdrms run around 62/65.

Open stairway goes down to basement's large, dark center room. North is short hall & door to unfinished furnace room.

No N.E. corner to house; it's a deck on the main floor w/ crouch-under outside storage.

East of center room are the 2 bdrms with large windows & ceiling air ducts. So furnace room is not far, just not adjacent to the bdrms. Est 10 feet, walking door to doors.

Is the humidifier worthwhile? Coworker sez they're a great theory, but didn't do much in his 2 (older) houses. I get a few "carpet" shocks, mostly downstairs.

Cooking, clothes washer, showering are all on the main floor. Maybe the Inf fan would push some of that humidity downstairs?

Sounds like dust isn't a deciding factor in the Inf/Perf wars. Great point! When near a sunny window & seeing how much is floating around, really, how much IS going to fall back into the return ducts?

Thank you so much for bearing with all this! Barb

[baffled]

Hi RoBoTeq -

I appreciate your explanation! It simply doesn't sound like going with the Inf is going to accomplish what I'd like it to regarding the colder basement, then, because the registers are up on the ceiling.

And as I've learned from Dash, it's not likely to do much of anything better dust-wise, either.

I can't think of any other reason to be running the fan all the time, then, so this tilts me back to the Perf, which seems to be a perfectly fine furnace.

If the Inf could deal with either of my challenges, I'd spring for it, but if it doesn't, I'll save the $$.

Thank you so much, both of you! I really appreciate getting the straight scoop from those who know it!

Barb

PS - I have a question about my haunted set-back thermostat, but I'll put that on a separate posting.

[beenthere]

As far as the dust, a good humidifier, and air filter system, no matter which unit you get.

[baffled]

Thanks for replying, beenthere. This got me curious, since I've never had a humidifier.

What role does it play in the dust problem? Is the dust "looser" to fly around if the humidity isn't there to hold it down? Sort of like the leaves blowing all over the lawn until today's rain?

Thanks!

Barb

[sprintmj19]

Im still kind of new at this, but 80,000 btu seems kind of small for 2,400 + sq ft.

Anybody else think this?

[dash]

Rooms that are not as cool or ,as warm as the rest of the home can be cured by Variable speed,like infinity or many others,true the root cause is the duct system,but variable sppedd may have moreability to move the air(more available external static pressure,to be technical).

We see the typical Florida home with ducts too small to get enough air to the Master Suite,cured or improved by variable speed.
But NOT always the ESP needs to be checked ,as well as duct sizes ,to determine if it can cure it,but it will almost always help it.

There are some furnaces with standard blowers that are similar in ability (Available Static),but not many.These furnaces may be less costly for normal blower operation,but it's rare.The variable on low or med. on the off cycle,will be less costly.Can you post the existing model number,to determine which you have.

Running the fan in the off cycle,will help,with rooms that are not the same temp. as the rest of the home.The rooms in question could also be that way due to lack of return air,air will not go where it can't get back to the return duct/grille.Leaving the dorr open to an area with a return will help,or adding a return or return "path".

[baffled]

Hi springmj19 - Thanks for replying!

I used the city assessor's listing which has other errors; may be a bit smaller. It's built into a pretty steep hill, where only the back half of the basement is exposed and has windows(to morning sun, no westerly winds.)

Old furnace is 60,000 btu. HVAC-Man asked me if it seemed too small for the house, if it was working too hard. Yikes! Wish I had some frame of reference! He recommended bumping up to the 80,000.

I'm certainly not arguing; you may well be right. I just don't know the answer! I'm just very grateful I don't have to pick out a color!! ;-)

Barb

[baffled]

Hi again Dash! What I currently have is a 23 yr old Carrier Weathermaker SX 58SX060, so it's 60,000 BTU.

On the main floor, it's pretty even temps. The small bedroom tucked on the south wall between the master bdrm & living room is the warmest room in the house.

Since it's across the hall from the thermostat, a friend recently suggested closing that door to not skew the temp the thermostat reads. I'd say it does make a bit of a difference, tho the southern Wisconsin winter isn't quite here yet. (Actually, it's been a beautiful, mild fall. So far.)

Are you thinking I should run the fan now & bring up the cooler basement air? It's an open stairway to the basement; I think heat comes out of all the ceiling registers downstairs, no cold air returns...but I could be wrong!

I can see where moving it up out of there means the air that refills it should have to be warmer. I can give it a try!

Ok...I turned the fan on, with the other button still set at heat. Hallway thermostat says 67; kitchen is 72 (oven ran recently) and basement by computer is 63.3 at 8:50 p.m. Will report back in a little while.

Thanks again, Dash!

Barb