DIY Home Improvement Forum banner

1 - 20 of 35 Posts

·
Registered
Joined
·
84 Posts
Discussion Starter · #1 ·
Hello,

2 years ago I purchased a 3 ton Carrier performance series A/C from a local company. I am now looking to replace my 14 year old furnace. I have received numerous quotes and have the following options

80% Carrier infinity series from company A - $4,100
58TN0A070C17--16
use all existing ductwork
5 year labor warranty

96% Carrier performance series from company A - $5,000
59TP6B060V17--14
5 year labor warranty
2 stage
includes extra work needed to upgrade existing system
pvc, replace the air return supply boot, add 4" filter

96% Carrier performance series from company B - $4,700
Same exact options as company A except only 2 year labor warranty

98% Carrier infinity series from company B
Price is $5,500 without infinity controller, $6,000 with infinity controller
59MN7A060V17--14
modulating

There are some other variables like rebates, but aside from that, can I please have a few opinions. I do intend to stay in the house for some time

I have an optional quote with both companies to also install an air exchanger or ERV ranging from $1,500-$2,000. Is an air exchanger going to really change the quality of the air that much?

I did receive several other quotes but they were considerably higher. 1 quote I received today was nearly $8,000.

Thanks
 

·
Registered
Joined
·
3,408 Posts
In most climates, if you upgrade from an 80% to a 95% efficiency or higher, it's highly recommended to upgrade the ductwork to add condensation drains, since the high efficiency furnaces run at a lower air temperature, so they may have some condensation in the ductwork that did not occur before.

To calcualte the payback period, you'll need the other side of the equation - what is efficiency and heating cost of your current system? You'll want to look at your past gas bills for the difference in the variable portions of the charges (those based on demand) between winter and summer. With that, you can roughly calculate the cost savings per year for the higher efficiency and see if the extra initial cost can be recouped in within a reasonable number of years. I (and I'm sure some others) can help with the math, if you need it.
 

·
Registered
Joined
·
168 Posts
I'd do the extra work/money to put in the PVC vent/exhaust.

A condensing, 2 Stage furnace hits the sweet spot in value/cost/efficiency I think, Not only is modulating more money but hardly more efficient I don't like that I'm forced to use the manufacture's thermostat, I think (hope?) one day there will be some standard around this and that won't be an issue. There is good competition from several companies making good thermostats.

A 4" filter is worth it and increasingly popular so easier/less expensive to find replacement filters, great thing to buy online.

As for the ERV, if you house isn't a particularly "tight" house (very well air sealed) it is less of an issue for you to have it. I would spend the money on caulking, weather-stripping, insulations windows if needed.

One gotcha I would ask about is, for the installation, does the company's employees do it or is the installation something that is contracted. This happened to me and there were problems, installation is important. I think the best companies only do their own installs, I think that shows they appreciate the importance of installation and they care.
 

·
Registered
Joined
·
3,974 Posts
Is your 14 year old furnace shot? I don’t know where you are but 20+ years is a typical life in western NY. I would buy a 90+ efficiency condensing furnace. I get the middle of the pack, not the least or greatest available. It has a flame and burns gas. Condensing squeezes out more efficiency. About everything else is controls. The more high end, the more complex and proprietary expensive parts.
 
  • Like
Reactions: Yodaman

·
Registered
Joined
·
84 Posts
Discussion Starter · #5 ·
To reply to all questions,

My existing furnace is an 80% efficiency unit. For some context, I live in Minnesota. It is a 2 story house, about 2,000 sq ft. Built in 1986.
There are some issues with the existing unit such as uneven cooling/heating on the 2nd floor. The furnace does work, but it isn't perfect.
I agree also that the furnace could last longer, but I have the funds now and my understanding there would be a huge difference in quality by getting newer technology including the filter size, the blower, and getting a 2 stage system.

I also agree about one of the comments and proprietary parts. I have read a few places that the Carrier modulating furnace isn't actually modulating without the control unit. And it is extremely expensive. I have a nest thermostat and am happy with it. The only reason i'd consider the upgrade from 96% to 98% is for 2 reasons. The gas company is offering a 500 rebate, and the price difference is less than $500, however when you figure in the cost of the infinity control unit, then the cost difference is more significant.

I had more than 5 companies come out to provide quotes and most of them were far more expensive for less quality units. You can usually tell they will be expensive when they show up in a vehicle that is completely covered in decals and carrying the $1,000 ipad.
 

·
Registered
Joined
·
168 Posts
Is your Nest thermostat 2-stage ready?

The problems with uneven cooling/heating on the upstairs most probably not be solved with a new furnace. If you tell them about this problem they should look into that.
 

·
Registered
Joined
·
3,408 Posts
The problems with uneven cooling/heating on the upstairs most probably not be solved with a new furnace. If you tell them about this problem they should look into that.
You beat me to it. I was just about to comment that the uneven heating is a duct/air movement issue, not a furnace issue.
 

·
Registered
Joined
·
13,512 Posts
agree also that the furnace could last longer, but I have the funds now and my understanding there would be a huge difference in quality by getting newer technology including the filter size, the blower, and getting a 2 stage system.
Your problems are most likely caused by ductwork or balancing dampers not set correctly and a new furnace will not fix them.

2-stage is nice, condensing is nice, but it makes zero sense to replace an existing 80% unit that could last 20 to 25 years. Have it thoroughly inspected/cleaned, tuned and run it until the heat exchanger cracks.

Your funds at this point may be better spent in energy efficiency upgrades - potentially duct changes too, to fix the balance problems.

As for the options, getting a new 80% 'er is Minnesota is crazy unless condensate drainage/venting are not practical.

The performance 96, I really don't like because the blower is variable speed but programmed to behave like a constant torque.
In layman's terms, this means the airflow goes down in heating mode as the duct pressure increases. The entire point of variable speed over multi-speed is to maintain consistent airflow over a wide duct pressure range. The 40 and 60k versions are particularly bad, the bigger ones not as bad.
Worst thing is, you can't adjust the heating fan speed on the performance 96 much (just a 10% adjustment) and if your ducts are small, you can be SOL.
The variable speed blower is very expensive to replace out of warranty and for this class furnace, you would be better off using another brand with a conventional 5-speed tap blower motor - heating speed/torque level manually adjustable and motor is cheaper to replace out of warranty.

York TM9Y, lennox EL296E, come to mind - the replacement blower is a generic off the shelf part. These models are sold under different names.

If you insist on carrier and want 2-stage, get the infinity 96 2-stage as they don't make a 2-stage/multi-speed -> if you're getting variable, you mightt as well get the one that isn't crippled. The modulator I wouldn't get due to repair costs.

Carrier parts can be super expensive out of warranty and difficult to acquire for the diy'er. I would use another brand personally unless the dealer is super good.

Make sure 2-stage furnace is paired up with a 2-stage t-stat and wired accordingly. No need for infinity control unless you get the modulator.

Most important things -> properly matching the furnace to the house and ducts, proper installation and commissioning.
 

·
Registered
Joined
·
84 Posts
Discussion Starter · #9 ·
Understood that getting a new furnace would not resolve the issues mentioned of uneven heat on the 2nd floor.

My justification for getting the new unit was
1. it would take combustion air from the outside vs inside the room
2. It would be new and I wouldn't have to take on a huge repair (hopefully)
3. It would come with a 4" filter which is much better than my existing 16x20x1 filter
4. It would have a better blower that would blow more air throughout the home (think this is true), because the blower I have is older technology
Would the newer blower not also help the air conditioning in the summer?

If you guys all think I should still save the money and just try to repair what I got, let me know.

Thanks
 

·
Registered
Joined
·
13,512 Posts
4. It would have a better blower that would blow more air throughout the home (think this is true), because the blower I have is older technology
The airflow requirements are dictated by the equipment. "More air" is not necessarily better - just need proper distribution.
You can get a competent tech to take measurements to determine if your system is moving the correct amount of air for heating and cooling.

ECM motors new units come with in general do a better job of maintaining airflow at high duct pressure - but reread what I said about the performance 96.

A new furnace won't necessarily come with a 4" filter. It is a good idea to use a media filter, especially on 80k+ units as they're far less restrictive to airflow at a given merv rating. You don't need to replace to get this now, but would have to pay more in labor.

You've given us almost no useful info about the existing equipment (furnace size and model), size of new proposed, ducts, or house.

Minnesota has brutal winters, right? Better make sure 60k proposed is enough - what size is your existing furnace and is the thermostat setting maintained in extreme weather?
If it can maintain running continuously, you don't need anything bigger.

If you want a new furnace, get a new furnace, but imo replacing a 14 year old one that's working fine is a waste of money which could be better spent elsewhere. Better to hold off.
 

·
Registered
Joined
·
168 Posts
You said that you notice uneven cooling/heating on the second floor, is the unevenness between the 1st and 2nd or within the 2nd. Is this unevenness especially bad for cooling or heating? About how old is the house?
 

·
Administrator
Joined
·
41,421 Posts
In most climates, if you upgrade from an 80% to a 95% efficiency or higher, it's highly recommended to upgrade the ductwork to add condensation drains, since the high efficiency furnaces run at a lower air temperature, so they may have some condensation in the ductwork that did not occur before.
Won't be any condensation in the duct work just because of going to a 95% or higher efficiency furnace.

There are no recommendations to install any drains in the duct work.
 

·
Administrator
Joined
·
41,421 Posts
Understood that getting a new furnace would not resolve the issues mentioned of uneven heat on the 2nd floor.

My justification for getting the new unit was
1. it would take combustion air from the outside vs inside the room

Do the proposals/estimates say they will 2 pipe it?

2. It would be new and I wouldn't have to take on a huge repair (hopefully)

See if the 5 year labor warranty requires you to have them service it every year.

3. It would come with a 4" filter which is much better than my existing 16x20x1 filter

If you pay for the 4" filter housing, it comes with it.

4. It would have a better blower that would blow more air throughout the home (think this is true), because the blower I have is older technology
Would the newer blower not also help the air conditioning in the summer?

If you guys all think I should still save the money and just try to repair what I got, let me know.

Thanks
In first stage, the blower will move less air than your current furnace does. Which could help your temp imbalances, or increase the imbalance.

It should be able to move more air in heating when in second stage, and of course move more air when in cooling mode.

However, the TESP should be checked after its installed to see if its too high or not. Because VS blowers don't last long at high statics, above 1" TESP.
 

·
Registered
Joined
·
7,593 Posts
Myself, I would be going with the 98% modulating furnace without the infinity controller.

I suppose it depends on your lifestyle, but I find it hard to understand why anybody needs to adjust their thermostat with their smartphone.

I did not check the other furnaces, but the modulating furnace will definitely have an ECM blower motor. If you set your fan to "ON" at the thermostat, it will run 24/7, but when the furnace is not on, the blower will run extremely slow. You won't even hear it. But that will help to equalize the temperature through the house. (Some suggest to turn off the fan in summer to minimize evaporation of moisture off the AC coils)

A 4" or 5" filter for sure. Better filtration than the old 1" fiberglass and only change it every 6 or 12 months.

For sure it has to be a high efficiency that takes combustion air from the outside. It Minnesota, It is idiotic (IMHO) to be using indoor air for combustion. For every cubic foot of combustion air that expelled through the exhaust, another cubic foot of cold Minnesota winter air will be sucked into the house though ever-present gaps and cracks.

Another nice thing about the modulating furnace it that it can run at lower output when its not extremely cold. Burning gas at a slower rate means needing less blower airflow, which is quieter than running with blower on high. At night, you may appreciate a quiet furnace. Make sure installer takes the time to set up all the parameters optimally.
 

·
Property Mgt/Maint
Joined
·
6,660 Posts
Personally I like the single stage 95% units. But I do my own installs and maint., so the added complexity of two stage for a point or two doesn't seam like a good trade off. Another thing to consider is your current chimney set up and the condition of it. Are you venting a furnace and hot water tank into it? Large masonry chimneys do not do well with only the HW vented once the furnace exhaust is pulled. The HW tank doesn't produce enough heat to dry it out. Generally a flue liner would be needed to vent the HW tank. So possibly some added expense that you were not expecting.
 

·
Registered
Joined
·
3,408 Posts
Won't be any condensation in the duct work just because of going to a 95% or higher efficiency furnace.

There are no recommendations to install any drains in the duct work.
That's not what I understood from my reading when I was shopping for a new furnace. Perhaps I misunderstood or was misinformed. Or does that issue only affect mobile home heating systems?

Upon further reading, it appears I misunderstood - the furnace needs a condensate drain, not the ductwork. There were also some comments about the venting needing to be changed to PVC(?)
 

·
Registered
Joined
·
6,487 Posts
That's not what I understood from my reading when I was shopping for a new furnace. Perhaps I misunderstood or was misinformed. Or does that issue only affect mobile home heating systems?

Upon further reading, it appears I misunderstood - the furnace needs a condensate drain, not the ductwork. There were also some comments about the venting needing to be changed to PVC(?)
Condensing furnaces require the use of PVC for venting. They cannot use a conventional chimney, nor share venting with another fuel burning appliance.
 

·
Registered
Joined
·
13,512 Posts
Myself, I would be going with the 98% modulating furnace without the infinity controller.

I suppose it depends on your lifestyle, but I find it hard to understand why anybody needs to adjust their thermostat with their smartphone.
The main benefit has nothing to do with wifi.
The infinity controller is required to tell the furnace what rate to fire at so heat output tracks heat loss.
Without it, the board calculates what rate to fire at based on previous cycles, and runs at that for only the first 20 minutes or so - after that it ramps up to high to satisfy the t-stat.


No point of spending extra on a modulator in that case, the point of that feature is to get a furnace to never shut off when heat loss matches or exceeds 40% of maximum output.

Looks like it can be set up as a 2-stage using basic 2-stage stat to do 40% on low, 100% on high which is better but then it doesn't modulate.
 

·
Registered
Joined
·
3,974 Posts
I got a new HVAC system 3 years ago and kept my old fashioned round manual thermostat. If I am uncomfortable, I adjust it. If I get home and the house is cool, I turn up the heat and wait a few minutes. I don’t need a smart thermostat, I don’t expect it to do my taxes or plot a trajectory to the moon.
 
  • Like
Reactions: Mike Milam

·
Registered
Joined
·
84 Posts
Discussion Starter · #20 · (Edited)
@user_12345a
I am not an expert so I don't know what details I could provide about my "ductwork", but here is the best i've got.


The existing system is a Trane XL80 manufactured in 2006 and installed in 2006. It has a 16x20 return and a 1" filter. I did have the existing unit inspected. The information they gave me
1. The blower was not blowing as strong as it could because the voltage being supplied to it was low. They recommended replacing something but it seemed expensive. The quote was 500-1200.
2. I could be wrong, but from my memory they showed me a photo of maybe the heat exchanger. They said it was not cracked but that it had wear signs. Something about there was no exhaust gas leaking but it could soon?

I converted the basement into a living space. I gutted and redid it myself using XPS insulation. The basement is divided by wall into 2 spaces. The furnace room and the living space. The living space is about 350-400sq ft. There is no return or supply or windows.

In the main floor, there are 2 living rooms, a kitchen, and a formal dining room. All mostly open. Each room has a supply or 2 supplies and a return. There are 2.5 baths in the home. All baths have a supply and no return. The 2nd floor has 4 bedrooms, decent size. Each room has a supply and return. The master bedroom has 2 supplies.

In the basement, there are 3 dampener toggles. I have tried adjusting them several times but basically what happens is it is good flow in 2 of the rooms and not so much in the other 2. One of the upstairs bathrooms has too much supply where it becomes hot, and it is a small bathroom. I have tried blocking the vent a bit and does help marginally. This uneven issue is consistent with both heat and air conditioning.

The work/prices that I mentioned in my first post include
the furnace option mentioned
Replacing the main supply with a 16x25 with 4" filter (shows on quote)
Raising the furnace off the ground so air is also sucked from the floor in addition to wherever else
Adding a supply and return into the basement living space
Will try and attach some photos also
IMG_2257.jpg
IMG_2261.jpg
IMG_2262.jpg
 
1 - 20 of 35 Posts
Top