Home A/C unit died-- by design.

[Hohn]

This is the kind of engineered obsolescence, designed-to-fail stuff that just infuriates me.


Our home A/C is a Trane XB10 from 2005, about 3 tons IIRC. It just died. Technician found the leak with his sniffer at the evaporator, which is a tube-and-fin style. IT has copper tubes with aluminum fins, pretty typical. At the end of each tube there are u-bends of copper brazed/soldered on to plumb all the tubes together. Also quite typical.

Ah, but the header plate at the end? GALVANIZED STEEL. Now, you might already know that zinc touching copper is going to cause galvanic corrosion of the copper. There's no way the engineers at Trane did NOT know this.

But who cares? That means when the evaporator fails in 15 years because of corrosion they could have prevented, you won't be able to get a replacement part (naturally, out with the old) so they'll get to sell you and entirely new system for $10,000+ because they decided to use cheaper galvanized steel instead of aluminum for the header plates.


So now the question becomes: Now what? What do I get to replace this rusty old dumpster fire of an HVAC system that has never worked very well in 20 years?


Since the furnace also needs to go (it's very rusty), I'm thinking just biting the bullet for a whole new system. The ducting in the house seems fine. But I'm pretty frustrated that my 2005 HVAC system is essentially no different from a 1960s unit-- single speed fan, single speed compressor, constant output furnace.


Best I can tell, I the smart call for my part of Indiana is a higher capacity heat pump with variable speeds on the compressor and fan and then have the gas furnace backup for when the heat pump cant keep up.


Sometimes being an engineer means living a life of frustration when you can see every defect of design right in plain sight. Especially when it costs you a small fortune.

 

[wwillson]

We put in a new mini-split AC/Heat pump 3 years ago. The AC efficiency (50% less electrical use) and quietness is so much better than the 25 year old unit it replaced. The compressor and condenser fan have variable speed motors and when running slow you literally can't hear them. The heat pump is ok, but puts out little heat below 30F and virtually no heat below 15F, but above 40F it's great. The heat pump is advertised to put out heat below 0F and that's just a bunch of hogwash. Have gas backup for cold weather and you'll be fine.

 

[Marcozi]

I think it depends on your budget. But, with the rising electricity rates I think the better long term solution is to go with a new system.

 

[iCurious]

We put in a new mini-split AC/Heat pump 3 years ago. The AC efficiency (50% less electrical use) and quietness is so much better than the 25 year old unit it replaced. The compressor and condenser fan have variable speed motors and when running slow you literally can't hear them. The heat pump is ok, but puts out little heat below 30F and virtually no heat below 15F, but above 40F it's great. The heat pump is advertised to put out heat below 0F and that's just a bunch of hogwash. Have gas backup for cold weather and you'll be fine.

I was gonna recommend this also.

 

[CDX825]

Wasn't just Trane making coils like that. Pretty much all of them were like that until they switched over to aluminum tube in fin coils.

 

[JavierH19]

My ac tech told me the variable speed units are not worth buying they break way more often and cost over two grand sometimes more to repair compared to a normal one and for the most part it's going to run about the same. The warranty is almost worthless from what he told me and said they blame the home owner or installer and don't care.

 

[GSCJR]

What exactly is the header plate?

 

[Rand]

When my seer 14 carrier goes I will go full heat pump with furnace backup.. and at least 2 fan speed.
house is small dont need 60k btu for 5-10min at a time.

20k or 30k btu over a longer period would be much more comfortable.

not that I want to spend a ton but even if you cap the system at 10 or 15 year life a little more $$$ at the start pays off fast.
OTOH sometimes the complicated systems have more issues.

I've love to disconnect gas from my house with its current $600 a year in connection fees. but not sure heat pump with maybe a few weeks of emergency electric is cheaper than $600 as our actual natural gas "rate" is very low compared to the high monthly connection fee.
Also electric rates are rising fast.

A heat pump that could put out 15k btu at 10f would suffice 95% of the time.. with a couple week cold snaps below 0 needing intermittent backup heat.
last winter even on the -15f day the furnace ran 33% of the time max. (60k btu) average run time was around 25% for January which was a very cold month.

So it likely makes the most sense to hedge against electric rates and get a Heatpump with 2 stage gas backup.
and run the gas below 25f or whatever number makes sense from efficiency.

And that is my own rambling post.. I dont put mine through an AI filter before posting


But back on topic: Finding a good installer is more important than the exact brand and model. Although a good conversation on what features you want is important.

 

[Jimmy_Russells]

What exactly is the header plate?

silver part

 

[hemitom]

20 years that's most lifetime warranties !
really not much to complain about these furnaces and a/c units aren't built like the 60s and 70s energy hogs .

 

[VolvoZ]

We put in a new mini-split AC/Heat pump 3 years ago. The AC efficiency (50% less electrical use) and quietness is so much better than the 25 year old unit it replaced. The compressor and condenser fan have variable speed motors and when running slow you literally can't hear them. The heat pump is ok, but puts out little heat below 30F and virtually no heat below 15F, but above 40F it's great. The heat pump is advertised to put out heat below 0F and that's just a bunch of hogwash. Have gas backup for cold weather and you'll be fine.

Curious what brand and size unit was installed to heat and cool what size space? Curious, as I am researching mini-splits now. It seems one need to oversize the unit to get “good” heat at the extremes. Thanks.

To the OP, understand your frustration.

 

[wwillson]

Curious what brand and size unit was installed to heat and cool what size space?

It's a Cooper & Hunter 2.4 ton (23,000 btu) unit - 21 SEER. The guy who sized it does that for a living. He really knew what he was talking about and the mini-split cools the second floor of the house effortlessly. The only variable speed units the installer will use is Cooper & Hunter and Toshiba, because they are highly reliable.

We leave the upstairs doors open during the day and let the cool air leak down to the first floor. The 25 year old first floor AC only runs on the very hottest days, like 98F or hotter. It's loud and sucks electricity.

If you have a two story house, I highly recommend split-zone cooling. I have only ever owned two story houses and this is the first house I have lived in that didn't have a hot second floor in the summer.

 

[DCDG]

Stick with a single stage bump up to a 13-14.9 seer. Ameristar and MR COOL got decent units.

 

[IndyIan]

Maybe take the old one to a radiator shop and see what they can find in the catalog that will work? Something roughly the same shape and capacity?

We went through this at my in-laws place, with a fancy 15 yr old heat pump... $2k in parts or a new one again, they went new.
It works out to like $1000-1200/year just for the unit.

At my house we've done well with a $300 window AC unit(it's ~15 yrs old), and a wood stove, which don't have too many expensive parts to replace. A couple fire bricks, and 2 air tubes in 20 years isn't bad!

 

[2002 Maxima SE]

My ac tech told me the variable speed units are not worth buying they break way more often and cost over two grand sometimes more to repair compared to a normal one and for the most part it's going to run about the same. The warranty is almost worthless from what he told me and said they blame the home owner or installer and don't care.

I heard the same. When we replaced our AC in 2020, we went with the most basic system with the best build (Lennox) on the size and capacity we needed.

The AC was 29 years old and the furnace was about 15 years old at that point. It was cheaper in the long run to replace both unit rather than wait 5 more years and replace the furnace.

 

[QwikKota]

Our new Lennox that was installed in 2015 didn't even make it 3 years before the coil leaked. It was just outside of the class action lawsuit as well. Had to pay for labor and refrigerant. I paid extra for the inverter drive, variable speed unit and was closely monitoring savings to see if the $3k extra I spent compared to a single speed unit would pay for itself. That went out the window real fast with the repair. I hate you Lennox.

 

[BrendanC]

I just installed an ACIQ system (Midea built, carrier’s inverters are midea) and couldn’t be happier with it. loved it so much i did the upstairs system right behind it with a MRcool dual fuel ducted heat pump. ACIQ extreme plus models will heat with 100% efficiency to -22°F. 12 year compressor warranty. 100% communicating system that will give you a “check engine light” when something is wrong.

 

[gman2304]

My old 1994 Trane XL- - - 4 ton ac unit except for a couple of capacitors, has been basically trouble free for 32 years. When it fails another Trane will take its place.