Replacing the whole house HVAC

[Hohn]

Not the same. Not a valid comparison.

On the contrary, it's quite similar. Those items require no maintenance and provide little to no warning before they fail. They go from fine to not fine in a step function. HVAC is like that. By your own admission, there's nothing one can do to prevent the kind of coil failure that took out my old system.

You've provided no alternative beyond a vague concept of proactive replacement as a form of maintenance. You've only identified age as a useful criterion, and it's quite debatable how useful that is. Our friends in Phoenix are lucky to get 10 years from a system.


The specific reason that proactive replacement of system like this is unwise is because the lifespan is highly uncertain. Yes, you might have half of them go bad in 15 years. But 10% of them might go 30 years. 5% might go 35 years.

And as a homeowner, you have no idea where your system falls within that wide life distribution. You could replace it at 15 years. But if yours was one of those that will go 30 years, you just spent a small fortune replacing something at half of its life.

When the lifespan is highly uncertain and the fail modes unable to be prevented, reactive replacement is perfectly rational if the downtime is of similar consequence in all circumstances. That's exactly the case here.

 

[danski0224]

You win.

 

[PoorUB]

On the contrary, it's quite similar. Those items require no maintenance and provide little to no warning before they fail. They go from fine to not fine in a step function. HVAC is like that. By your own admission, there's nothing one can do to prevent the kind of coil failure that took out my old system.

You've provided no alternative beyond a vague concept of proactive replacement as a form of maintenance. You've only identified age as a useful criterion, and it's quite debatable how useful that is. Our friends in Phoenix are lucky to get 10 years from a system.


The specific reason that proactive replacement of system like this is unwise is because the lifespan is highly uncertain. Yes, you might have half of them go bad in 15 years. But 10% of them might go 30 years. 5% might go 35 years.

And as a homeowner, you have no idea where your system falls within that wide life distribution. You could replace it at 15 years. But if yours was one of those that will go 30 years, you just spent a small fortune replacing something at half of its life.

When the lifespan is highly uncertain and the fail modes unable to be prevented, reactive replacement is perfectly rational if the downtime is of similar consequence in all circumstances. That's exactly the case here.

Danski is in the trade so of course it is best just to rip out the system every 15 years and replace it.

I was on HVAC for 22 years. My house unit is ~20 years old and zero plans to replace it. The central air and gas furnace in my garage is ~30 years old, and again, not replacing it. I did replace the heat exchanger in the garage unit about ten years ago. I suspect from running it at 55F and it just rotted out. I get tempted to buy a replacement heat exchanger to keep on hand as replacing the heat exchanger is a 45 minute job versus all day for a new furnace.

One reason I keep running the old equipment? It is good solid equipment and I don't believe any of the new equipment is as good, and will not run as trouble free as my existing.
As for your duct work, yes, it could be better, but 99 out of 100 residential installers would have done it the same way. Nobody in residential puts turning vanes in duct. I have never seen it done.

 

[danski0224]

Danski is in the trade so of course it is best just to rip out the system every 15 years and replace it.

A lot of the stuff I see at the 15-20 year mark is shot.

Or needs significant repair. I do not consider replacing a compressor on a 20 year old condenser to be a good decision.

I actually just looked at one. Evap coil end sheets are rusty. Furnace has to be removed to replace the evap.

Then what. Put the 20 year old furnace back?

This isn't an experiment at my house for fun... it's a paying customer.

And no cooling becomes an emergency in this case. It's "working" for now but the compressor is not working properly.

For some on this board, replacing the compressor can be a viable DIY option and keep running it. That situation is rare.

Just doing the compressor was on the table, but the person decided to replace the equipment instead. Took a couple of weeks for them to make the decision.

 

[Hohn]

I agree fully with that, which is why instead of throwing $2k into a repair of uncertain utility and effectiveness, I just applied that money to a new system with as much replaced as reasonably made sense.

 

[PoorUB]

A lot of the stuff I see at the 15-20 year mark is shot.

Or needs significant repair. I do not consider replacing a compressor on a 20 year old condenser to be a good decision.

I actually just looked at one. Evap coil end sheets are rusty. Furnace has to be removed to replace the evap.

Then what. Put the 20 year old furnace back?

This isn't an experiment at my house for fun... it's a paying customer.

And no cooling becomes an emergency in this case. It's "working" for now but the compressor is not working properly.

For some on this board, replacing the compressor can be a viable DIY option and keep running it. That situation is rare.

Just doing the compressor was on the table, but the person decided to replace the equipment instead. Took a couple of weeks for them to make the decision.

Well, of course you don’t put a compressor in a 20 year unit that is rusted out, I never said that. But a 20 year old AC unit that is in good condition that needs a contactor or a capacitor is worth saving.

Each unit needs to be evaluated on its own. I have seen five years old units that are shot, and 25 year old units that look like new because the owner took care of them, but to condemn a system just because it is 15 years old is poor judgment.

If my furnace died today I would replace it and save the other. If the AC died I probably would replace both. It depends on the situation.

My daughter and son in law are dealing with this right now. The AC is shot and they asked me for some advice. Both myself and the two contractors that gave quotes said save the 15 year old furnace an replace the AC.

I would do it for them, but they are 1,000 miles away and I don't have all the tools anymore.

 

[Firebrick43]

This morning I was at a customers place and they had an old blue green condenser unit that looked like it weighed a ton.

Owner said they installed it in 1982 and it’s still kicking.

He said they installed furnace before that, also a Williamson.

 

[bob smith1]

Good commentary! Just my experience but 98% of HVAC time is taken up with the "equipment selection" and SOOOO little time is ever invested or respected in the ducting! It's just so friggin pathetic in industry! Anemic returns, supply pressures that guarantee problems, then the equipment is blamed.

There is nothing like a proper design, then flow testing everything when done, and tuning it in onsite. We all know how it usually goes and that's half the owner's ignorance to blame. Cheapest guy wins, and a race to the bottom.

I honestly get SO tired of hearing the tech BS, "it's old". Man, I have a system in my old place that I installed USED, 30yo, R22, and I dialed that thing right TF in before I sold it. Still running! Copland scroll still sounded mint, temps/pressures spot on, etc. My experience in the field is techs blow off simple things like clogged evap/cond, poor charge work, and totally oblivious to ducting issues. The race is to leave and collect cash.

Ducting is like insulation, its one time cost and value should be a no brainer.

As for equipment, I just have a hard time justifying elites like Trane, but when they run, they run good. I still eval Goodman as a decent value. I'm a big fan of inverter compressors but I also realize I know how to fix em, and from a pro callback perspective, I'm not sure I'd want to deal with it! I've been F'd with that one cheap fitting I used, and causes the phone call, the drive, the talk, the loss.

 

[aggie113]

The specific reason that proactive replacement of system like this is unwise is because the lifespan is highly uncertain. Yes, you might have half of them go bad in 15 years. But 10% of them might go 30 years. 5% might go 35 years.

And as a homeowner, you have no idea where your system falls within that wide life distribution. You could replace it at 15 years. But if yours was one of those that will go 30 years, you just spent a small fortune replacing something at half of its life.

Another reason for replacement of a working unit could be levels of efficiency to be gained. My old running RUUD 3 ton unit was rated as a 13 SEER (no way it was getting that with it's too small return setup). My new Mitsubishi unit is rated for 21 SEER and also replaced propane heating with electric. Even with my (currently) pretty affordable kWh rate, I do plan to try running most of the time off of solar in the near future. Added benefit is also the less harsh start with the heat pump vs the traditional style compressors (but that could be irrelevant in other setups).

 

[paulsomlo]

I'm in the same place, but worse - 50 year old gas furnace and AC that hasn't worked in years; can you give us a ballpark on what this cost you?

 

[danski0224]

About twice as much as it was 10 years ago, and less now than next year.

 

[Hohn]

I'm in the same place, but worse - 50 year old gas furnace and AC that hasn't worked in years; can you give us a ballpark on what this cost you?

YMMV, this was in the mid 10s K.

FWIW, when I lived in Cheyenne (not from from you in Northern CO) we had a swamp cooler and always thought it sufficient. The air is already dry and water readily evaporates, so even on the hottest nights the swamp cooler seemed sufficient.


Obviously if your AC hasn't worked in years, you've basically concluded as we did that a/c in that region isn't a must-have.

 

[Notgrownup]

I ask my HVAC guy every year if it’s time . He always says it’s fine for now. I told him when it’s time I will gladly switch. Ha to.d me to use it til it is more than $1000 to replace or repair The part. I believe I will be able to keep my ductwork, it seems fine. I’m ready for a new HVAC & Roof At 23 years in this house from new.
One thing he told me, I would never make up the investment just by replacing it. Sure, a new system is more efficient but I would never recoup my investment.

 

[Hohn]

Maybe it's pedantic to say so, but I don't consider buying things that go down in value to be an investment. I consider them to be expenses.
Simply getting something in return for your money doesn't make it an investment.

Comfortable air in your home is mostly a luxury. And luxury is an expense.

 

[MovingAlong]

One thing he told me, I would never make up the investment just by replacing it. Sure, a new system is more efficient but I would never recoup my investment.

Swapped out a decades old system on a house, new duct work too. Went with a fully variable speed unit and it did cut my electric in half. The difference in comfort inside was spectacular too! Would have recouped cost in 10 yrs but sold and moved a year after installation.

Maybe it's pedantic to say so, but I don't consider buying things that go down in value to be an investment. I consider them to be expenses.
Simply getting something in return for your money doesn't make it an investment.

Comfortable air in your home is mostly a luxury. And luxury is an expense.

I follow your thought process on this. But during a sale, being able to show a new HVAC system with transferable warranty was a plus.

So while you're correct, the HVAC system did depreciate some, the value of the house went up more.

 

[danski0224]

I follow your thought process on this. But during a sale, being able to show a new HVAC system with transferable warranty was a plus.

So while you're correct, the HVAC system did depreciate some, the value of the house went up more.

Not always true.

It either works, or not. Average homeowner doesn't care about anything else.

"Home Inspectors" flag anything HVAC over 10 years old in my area.

 

[Jackfre]

“Much larger” have to laugh at that one. When the regs required the higher efficiencies I recalled hearing that the central condensers were going to be a lot bigger. I was representing Fujitsu at the time and went to the ASHRAE show. I was shocked when I walked by the Lennox booth looking the size of their 5 ton condenser which was on display. I went into the booth examining this thing, walking around it as a Lennox salesman waked up cheerfully asking if he could help. I asked him where the door was. He looked at me like I had rocks in my head, which is arguable, and went along with it asking why it should have a door. I replied that if I was buying something this large I would also want to at least park the lawnmower in it. Well, one of us enjoyed the conversation.

 

[paulsomlo]

YMMV, this was in the mid 10s K.

FWIW, when I lived in Cheyenne (not from from you in Northern CO) we had a swamp cooler and always thought it sufficient. The air is already dry and water readily evaporates, so even on the hottest nights the swamp cooler seemed sufficient.


Obviously if your AC hasn't worked in years, you've basically concluded as we did that a/c in that region isn't a must-have.

It wasn't a must have until this year; we just had a string of 100 deg days, cooler today, but 5 days of 100+ coming up. I bought one of these last night: https://www.lowes.com/pd/MasterCool-2000-sq-ft-Window-Evaporative-Cooler-4000-CFM/50342060

 

[Hohn]

“Much larger” have to laugh at that one. When the regs required the higher efficiencies I recalled hearing that the central condensers were going to be a lot bigger. I was representing Fujitsu at the time and went to the ASHRAE show. I was shocked when I walked by the Lennox booth looking the size of their 5 ton condenser which was on display. I went into the booth examining this thing, walking around it as a Lennox salesman waked up cheerfully asking if he could help. I asked him where the door was. He looked at me like I had rocks in my head, which is arguable, and went along with it asking why it should have a door. I replied that if I was buying something this large I would also want to at least park the lawnmower in it. Well, one of us enjoyed the conversation.

Yeah, I think part of why the new condenser is to big is that they're trying to dump the same heat with lower air velocity and less restriction (less fan work).
That and maybe the compressor discharge temps are lower and you get less effective heat transfer with a cooler condenser?
I expected it to be a little bigger going 3.5T to 4T, but it's 40% bigger or so for about 15% more capacity.

 

[gahrajmahal]

Square throat elbow on the return? Ugh.

Just to add another observation for those of us on the purchasing end of HVAC. My son had a nightmare room addition to his two story 1920’s home. His “contractor” talked him into getting a second heat/cool unit for his home. He contracted out the HVAC work and then didn’t pay the contractors, so he had a total of three guys install this unit. The addition was built over a crawl space, so the new unit is in the basement next to an old 2’ x 3’ basement window. They installed the return air duct as several 2’ flexible insulated ducts all stuffed through the small window opening. The 50’? Length ducts were opened from the box and attached to the round outlets located in the crawl space and connected to a box on the side of the new furnace/ac unit. So, the extra lengths from the box were snaked back and forth in the crawl space and crimped as they went through the small window. We couldn’t get passed for permit inspection because the wiring was too small for the amp requirements and the breaker was the wrong type and too small too. The inspector suggested “we” meaning grandpa (me) and my son just repair these errors ourselves rather than getting these pissed off HVAC proprietors to return and fix it. (Which one was responsible?) I spent two days in that cramped crawl space on my back un-snaking those flex hoses, shortening and straightening and supporting them. We ran a new correct gauge wire and purchased a breaker as recommended by the city inspector.

The whole addition has been complete for about three years now and the second heat/ac unit seems to be alright. If I had seen the return air setup the OP received with his installation, I would have been tickled to death by its clean and uncomplicated application.

 

[danski0224]

If I had seen the return air setup the OP received with his installation, I would have been tickled to death by its clean and uncomplicated application.

There are 2 general problems.

1. The homeowner does not know what they are looking at, in order to try and ask educated questions.
2. The homeowner doesn't care, or is not interested in the slightest, and therefore does not ask the questions.

These things kind of help allow the HVAC contractors to do whatever they want to, and it is typically skewed to the "just OK enough to sort of work" direction.

 

[Hohn]

Just to add another observation for those of us on the purchasing end of HVAC. My son had a nightmare room addition to his two story 1920’s home. His “contractor” talked him into getting a second heat/cool unit for his home. He contracted out the HVAC work and then didn’t pay the contractors, so he had a total of three guys install this unit. The addition was built over a crawl space, so the new unit is in the basement next to an old 2’ x 3’ basement window. They installed the return air duct as several 2’ flexible insulated ducts all stuffed through the small window opening. The 50’? Length ducts were opened from the box and attached to the round outlets located in the crawl space and connected to a box on the side of the new furnace/ac unit. So, the extra lengths from the box were snaked back and forth in the crawl space and crimped as they went through the small window. We couldn’t get passed for permit inspection because the wiring was too small for the amp requirements and the breaker was the wrong type and too small too. The inspector suggested “we” meaning grandpa (me) and my son just repair these errors ourselves rather than getting these pissed off HVAC proprietors to return and fix it. (Which one was responsible?) I spent two days in that cramped crawl space on my back un-snaking those flex hoses, shortening and straightening and supporting them. We ran a new correct gauge wire and purchased a breaker as recommended by the city inspector.

The whole addition has been complete for about three years now and the second heat/ac unit seems to be alright. If I had seen the return air setup the OP received with his installation, I would have been tickled to death by its clean and uncomplicated application.

It's a sliding scale for sure!

There's always something better, especially to a pro who has the knowledge to play the purist.

But good enough truly is good enough.

 

[Hohn]

There are 2 general problems.

1. The homeowner does not know what they are looking at, in order to try and ask educated questions.
2. The homeowner doesn't care, or is not interested in the slightest, and therefore does not ask the questions.

These things kind of help allow the HVAC contractors to do whatever they want to, and it is typically skewed to the "just OK enough to sort of work" direction.

I agree, those two aspects are quite commonly true. Contractors can get away with very shoddy work because the customer doesn't know enough to hold them accountable. The more specialized these things become, the worse it gets.

I know enough to think I know a few things, but not enough to really know what I don't know, so it's sort of "a little knowledge is dangerous" kinda thing. I ask a lot of questions and let them explain to me and teach me about what they're doing as they work. I think this interest and general understanding of things makes the contractors do better work. I can't say whether that's because they know they'll get busted on cut corners or whether because they just want to please an engaged and friendly customer.

I'm very pleased with the system as well as the installation. Living with the system now a couple days I can say it's far better than "just ok enough to sort of work." It's superb, actually.

The dehumidification is quite amazing, especially that morning period where normally the a/c doesn't run because it's cooler outside than inside and you hit your setpoint hours ago in the middle of the night. The electronic expansion valve that lets the coil stay cool even at really low output means that the system can throttle the air mover way down to a tiny amount of flow, but keep a very cold coil. This gives even higher tonnage per CFM of air movement by longer dwell time over the coil. That means the system become more effective at dehumidifying at lower output than it is at higher output.

I've turned off my standalone dehumidifer. I don't need it anymore.