Cost of a new central air system

[brianl703]

Ideally, more expensive, hard pipe would be used for main lines with flex branching to individual rooms in order to reduce noise transmission but that requires planning at the design stage and good luck with that on anything but a custom build.

Even better is when it's hard pipe AND the ductwork is entirely within the conditioned space (basement and between 1st and 2nd floors), as it is in my house.

No duct work is in my attic. The builder has a sales sheet explaining why their houses are more energy efficient and "No HVAC equipment or ducts in the attic" is one of the bullet points.

I lived in a house that just had the ducts for the top floor in the attic (3 level townhouse, basement plus middle and top floor).

In the summer, it blew hot air for 30 seconds when the system came on.

In the winter, it blew cold air for 30 seconds when the system came on.

Who knows how much the ducts were leaking in the attic...they weren't sealed with anything more than foil tape...

...which brings me to the 2nd bullet point they had, "Ducts sealed with mastic".

Although I think that may have already been a building code requirement by then, pretty sure it is now.

 

[doublebase]

This is exactly the design of my system. Large main duct down the middle of the attic with flex coming off each side in the shortest runs possible and as straight as possible. It works well with good even airflow to all rooms.

Yeah that is basically my setup...14” round ductwork coming off the main air handler going in two different directions, with flex ductwork branching off the solid 14” metal tubing. With a damper for each side coming off the A coil.

 

[PWMDMD]

Yeah that is basically my setup...14” round ductwork coming off the main air handler going in two different directions, with flex ductwork branching off the solid 14” metal tubing. With a damper for each side coming off the A coil.

I have a 4-ton unit and a lot goes into duct design so this is an apples to grapefruit comparison but my main trunk supply, besides being rectangle, is MUCH larger than 14". If I had to guess, my two returns are 14x14 and 14x30 and the main supply trunk is equal to the cross sectional area of both returns or equivalent to ~20x30 or 600 sq inches in cross-sectional area.

Your main being round and 14" has 154 sq inches x 2 or 308 sq inches total of total supply area? I guess in my apples to pineapple comparison that makes sense.

 

[doublebase]

I have a 4-ton unit and a lot goes into duct design so this is an apples to grapefruit comparison but my main trunk supply, besides being rectangle, is MUCH larger than 14". If I had to guess, my two returns are 14x14 and 14x30 and the main supply trunk is equal to the cross sectional area of both returns or equivalent to ~20x30 or 600 sq inches in cross-sectional area.

Your main being round and 14" has 154 sq inches x 2 or 308 sq inches total of total supply area? I guess in my apples to pineapple comparison that makes sense.

Nice, so what I’m gathering from this is that my upstairs unit is not only most likely underpowered, but needs larger ducts. Upstairs is a 2.5 ton unit, and downstairs is a 3 ton unit. The downstairs unit has excellent airflow/cooling. The A coil is in the basement (For the downstairs unit). In my mind the upstairs unit should have had a bigger unit, but I was told that bigger does not always mean better, and that what would happen in my case was that the compressor would cycle on and off too frequently because it would cool too quickly and then need to turn back on (or something like that). But I imagine that’s not the case and I’ll have to live with what I have.

 

[John105]

Nice, so what I’m gathering from this is that my upstairs unit is not only most likely underpowered, but needs larger ducts. Upstairs is a 2.5 ton unit, and downstairs is a 3 ton unit. The downstairs unit has excellent airflow/cooling. The A coil is in the basement (For the downstairs unit). In my mind the upstairs unit should have had a bigger unit, but I was told that bigger does not always mean better, and that what would happen in my case was that the compressor would cycle on and off too frequently because it would cool too quickly and then need to turn back on (or something like that). But I imagine that’s not the case and I’ll have to live with what I have.

I’m no hvac genius but imho it’s not likely a contractor would miscalculate the size of the condenser. And very often they are replacing using existing ductwork.

I think if ducts inadequate it’s the same as blower set too low. The unit will run longer and ice up. The temps may be very low out the vents. Usually there is a 20-22F drop. When my new system was installed, 43F. The blower was set the same for heat and ac, 600’ish cfm.

Oversizing is not an answer. The cycles will be short and potentially inadequate airflow. All lead to uncomfortable in the dwelling.

We feel comfortable when the system is on due to dehumidifying. I’d have to look but I think our system is on 10 min, off 10 min. When it’s super hot, the “off” is less. There is an ideal cycle.

Now I asked our office in Glendale AZ what’s the best the AC can do? I think it’s oversized so at 117F, they can be 85F inside. That’s not typical in the northeast to drop it by that much.

 

[doublebase]

I’m no hvac genius but imho it’s not likely a contractor would miscalculate the size of the condenser. And very often they are replacing using existing ductwork.

I think if ducts inadequate it’s the same as blower set too low. The unit will run longer and ice up. The temps may be very low out the vents. Usually there is a 20-22F drop. When my new system was installed, 43F. The blower was set the same for heat and ac, 600’ish cfm.

Oversizing is not an answer. The cycles will be short and potentially inadequate airflow. All lead to uncomfortable in the dwelling.

We feel comfortable when the system is on due to dehumidifying. I’d have to look but I think our system is on 10 min, off 10 min. When it’s super hot, the “off” is less. There is an ideal cycle.

Now I asked our office in Glendale AZ what’s the best the AC can do? I think it’s oversized so at 117F, they can be 85F inside. That’s not typical in the northeast to drop it by that much.

That’s exactly what I was banking on, the house was built years ago, it was a high quality home, and I imagine some thought went into the design of the system. I imagine it functioned pretty well. I wouldn’t know because I’m not the original owner, and I’ve had top floor AC issues since the initial home inspection three years ago. Now that it’s a new unit, I’m hoping for the best. But who knows? Since I fixed the motorized damper it really hasn’t been that hot out yet. The test will come next week.

One thing I probably should have mentioned - the AC system ductwork is not used for heating. The heating system is forced hot water baseboard.

 

[Donald]

Any idea what a new ac system goes for today? My 22 year old unit died. I have two units, the upstairs unit has not been able to keep up with keeping temp when very hot. The shutoff box just melted. Figure the compressor failed or something, either way, it was on borrowed time.

My upstairs square footage is pretty big 2,000 feet or so. I imagine I’d need an entire new setup, as the old refrigerant is obsolete now. I’m hoping to use my existing ductwork. I’m in the New England area.

Heat pump and take the tax credits. Also depends upon how long you plan to live there. Some units have a longer warranty than others.
I think Trane is one of the top brands. But quality of installation is important also.

I think there is some "charge as much as you think they will pay" going on with quotes from some places. Some places give the repair guys a bonus if they say while looking at your broken system "it's not worth repairing, you need a new one". Whether it's true or not.

What I never understood is if you look at the dealer cost of the system, a reasonable hourly rate, there seems to be a lot of extra $$ in the quote.

 

[John105]

What I never understood is if you look at the dealer cost of the system, a reasonable hourly rate, there seems to be a lot of extra $$ in the quote.

Isn't the same true of car repair, home repair, everything under the sun other than rock auto/DIY?

What is fascinating about HVAC, is the support aspect. I think it's like computer stuff where the support when needed, is disproportionate to the intial investment.

Also, those coupons, $3000 off! $5000 off! are not needed. One's mouth is one's coupon lol

Anyone do Costco? I canceled the appt. but would be curious if they save anything at all.

I've read that without a maintenance contract, and with factory warranty, AC breaks year 1, it could be $1000+ to fix under warranty (reminds me of the Nissan Rogue--CVT fails at 39k in 2-4 years, powertrain 5/60k, not covered).

Also imho when a system goes in, 75% of the current vendors, will not be around 10 years from now, when they're selling a 10 yr. warranty. The above is puzzling.

 

[totegoat]

About $8K to replace 4 ton AC and heater in attic. Reputable outfit did the job quickly.

 

[doublebase]

Heat pump and take the tax credits. Also depends upon how long you plan to live there. Some units have a longer warranty than others.
I think Trane is one of the top brands. But quality of installation is important also.

I think there is some "charge as much as you think they will pay" going on with quotes from some places. Some places give the repair guys a bonus if they say while looking at your broken system "it's not worth repairing, you need a new one". Whether it's true or not.

What I never understood is if you look at the dealer cost of the system, a reasonable hourly rate, there seems to be a lot of extra $$ in the quote.

A little late for that - just had two units replaced for $14,000 total. A 2.5 ton and 3 ton.

I did ask about installing condensers outside that could provide heating as well, was told I’d never make my money back (planning on staying another five years).

 

[Donald]

A little late for that - just had two units replaced for $14,000 total. A 2.5 ton and 3 ton.

I did ask about installing condensers outside that could provide heating as well, was told I’d never make my money back (planning on staying another five years).

Tax credits may change that calculation.

 

[Donald]

Isn't the same true of car repair, home repair, everything under the sun other than rock auto/DIY?

What is fascinating about HVAC, is the support aspect. I think it's like computer stuff where the support when needed, is disproportionate to the intial investment.

Also, those coupons, $3000 off! $5000 off! are not needed. One's mouth is one's coupon lol

Anyone do Costco? I canceled the appt. but would be curious if they save anything at all.

I've read that without a maintenance contract, and with factory warranty, AC breaks year 1, it could be $1000+ to fix under warranty (reminds me of the Nissan Rogue--CVT fails at 39k in 2-4 years, powertrain 5/60k, not covered).

Also imho when a system goes in, 75% of the current vendors, will not be around 10 years from now, when they're selling a 10 yr. warranty. The above is puzzling.

I use the same company who had installed the system and maintained it for previous owner.

Trane has a 10 year warranty for parts. I paid $100 to transfer it to me as second owner. The HVAC company offers a service contract for about $150 per unit so $300 for the house. They come 2x a year and change filters, clean condensate lines and check some readings. Hopefully they catch things like a bulging capacitor before they fail. If you maintain the service contract then will cover labor to repair the Trane heat pumps. And Trane covers the parts under the Trane warranty.

 

[John105]

I use the same company who had installed the system and maintained it for previous owner.

Trane has a 10 year warranty for parts. I paid $100 to transfer it to me as second owner. The HVAC company offers a service contract for about $150 per unit so $300 for the house. They come 2x a year and change filters, clean condensate lines and check some readings. Hopefully they catch things like a bulging capacitor before they fail. If you maintain the service contract then will cover labor to repair the Trane heat pumps. And Trane covers the parts under the Trane warranty.

I’m referring to the mfg warranty. I’ve read online people have paid $1000+ for a repair, despite a part being covered under a factory warranty. Example, compressor replacement. Part and labor covered, but not refrigerant for the repair, etc.

My job was not broken out. It included a repair contract for 10 years, and a chimney liner. Again I’ve searched online and that’s $1500-$3000 retail. I guess when we ask, “what does hvac cost,” we’re likely not comparing apples to apples. I can see this when 5 contractors have 5 prices, even for the same TRANE. Also interesting when some are not pushing a high efficiency furnace, which costs more, yet needs a chimney liner and more labor to drill through the foundation.

 

[4WD]

I’m referring to the mfg warranty. I’ve read online people have paid $1000+ for a repair, despite a part being covered under a factory warranty. Example, compressor replacement. Part and labor covered, but not refrigerant for the repair, etc.

My job was not broken out. It included a repair contract for 10 years, and a chimney liner. Again I’ve searched online and that’s $1500-$3000 retail. I guess when we ask, “what does hvac cost,” we’re likely not comparing apples to apples. I can see this when 5 contractors have 5 prices, even for the same TRANE. Also interesting when some are not pushing a high efficiency furnace, which costs more, yet needs a chimney liner and more labor to drill through the foundation.

Just did - $1500 for labor and materials to replace compressor - purge - refill and test system …
Parts covered by factory …

 

[doublebase]

Just did - $1500 for labor and materials to replace compressor - purge - refill and test system …
Parts covered by factory …

Good to know, I figured a warranty replacement for a compressor would be around $500. Guess I was wrong.

That‘s one thing I’m worried about with the units I had installed recently - the warranty on the compressors are I believe 8 years, but I had the old line set flushed and reused. The blasted an acid through the lines to remove the old refrigerant oil, but I’ve read that there‘s a possibility that remaining oil can mix with the new oil and sludge the compressor up. Because the oils are not compatible.

I’ll tell you what, I’ve learned a lot from this thread...and others. I was able to diagnose the damper by forums like this, pretty cool.

 

[PWMDMD]

A little late for that - just had two units replaced for $14,000 total. A 2.5 ton and 3 ton.

I did ask about installing condensers outside that could provide heating as well, was told I’d never make my money back (planning on staying another five years).

Tax credits/power company rebates were almost $7k for me to put in a heat pump vs AC. I have a SEER 20.5 system for the price of bargain basement basic AC.

I used about ⅔ the oil I normally use last winter and my electricity is much cheaper than the btu-equivalent price of oil. I saved about $1000 in heating costs in one season - mileage will admittedly vary depending on electricity costs and oil prices.

 

[John105]

Good to know, I figured a warranty replacement for a compressor would be around $500. Guess I was wrong.

That‘s one thing I’m worried about with the units I had installed recently - the warranty on the compressors are I believe 8 years, but I had the old line set flushed and reused. The blasted an acid through the lines to remove the old refrigerant oil, but I’ve read that there‘s a possibility that remaining oil can mix with the new oil and sludge the compressor up. Because the oils are not compatible.

I’ll tell you what, I’ve learned a lot from this thread...and others. I was able to diagnose the damper by forums like this, pretty cool.

I literally knew zero about airflow before 2016. My old 1999 Bryant, the blower speed is set with jumpers. As it aged the heat had to be changed to high. It short cycled.

The 2020 TRANE has a ECM motor so set by laptop as I witnessed. They set the AC same as heat and the brand new system froze despite 90F temps

My low side had ice, as well as the outside of the compressor.

That was another thing I had thought the XLi TRANES had a blanket on the compressors, I wanna say orange colored. They did away with them

 

[doublebase]

Tax credits/power company rebates were almost $7k for me to put in a heat pump vs AC. I have a SEER 20.5 system for the price of bargain basement basic AC.

I used about ⅔ the oil I normally use last winter and my electricity is much cheaper than the btu-equivalent price of oil. I saved about $1000 in heating costs in one season - mileage will admittedly vary depending on electricity costs and oil prices.

Yeah, my state didn’t offer much in rebates. That played a big part in it.

 

[PWMDMD]

Good to know, I figured a warranty replacement for a compressor would be around $500. Guess I was wrong.

That‘s one thing I’m worried about with the units I had installed recently - the warranty on the compressors are I believe 8 years, but I had the old line set flushed and reused. The blasted an acid through the lines to remove the old refrigerant oil, but I’ve read that there‘s a possibility that remaining oil can mix with the new oil and sludge the compressor up. Because the oils are not compatible.

I’ll tell you what, I’ve learned a lot from this thread...and others. I was able to diagnose the damper by forums like this, pretty cool.

I always replace the line set…

 

[doublebase]

I always replace the line set…

Yeah I wish they had. They would have had to run lines up the wall outside the house, which I was fine with, but they didn’t want to. Hopefully not replacing them doesn’t come back to haunt me.