Home A/C unit died-- by design.

[dogememe]

long term reliability from gree hasn’t been great nor parts. they’re also just loud compared to AUX, Midea. they do use a hot vapor line to heat the bottom pan for heat pump usage which is very intuitive. they also have a crank case heater which i’m not sure ever turns off so they use a bit more power than the others. regardless like I said it’s a great system, just not my preference. same thing with an “american” inverter system. it’s all marked up Midea technology. look at the bosch, top dollar for again, a midea built system lacking the features of midea or ACIQ/mrcool/senville. Carrier rebrands the midea EVOX line with quite literally just a name and paint job but sells it at a 100-150% markup because it has “carrier” on it.

Well ours is already installed and I paid zero so it’s firmly in the not my problem camp BUT I do appreciate the information and more knowledge is always better.

I’m slightly miffed they didn’t give us a smart thermostat. I asked for that and even offered to buy the one I wanted. Oh well.

 

[BrendanC]

Well ours is already installed and I paid zero so it’s firmly in the not my problem camp BUT I do appreciate the information and more knowledge is always better.

I’m slightly miffed they didn’t give us a smart thermostat. I asked for that and even offered to buy the one I wanted. Oh well.

pull the cover off of your air handler and look for an A B and G terminal. if it is there, you really should get Gree’s communicating thermostat. you are missing out on quite a bit of efficiency and comfort if you’re using a standard 24v thermostat. also, make SURE there is a surge protector at the outdoor condenser and the air handler. if there isn’t one, they’re about $40 each on amazon and a 5 minute job to add if you’re handy.

 

[Rand]

Could you link the surge protector you would use?

 

[BrendanC]

Could you link the surge protector you would use?

https://a.co/d/05080vTn for each appliance at disconnect properly pigtailed.

https://a.co/d/0a99GmQ3 at electrical panel on seperate 30amp breaker.

 

[oil pan 4]

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.

This is why I hate central hvac. Its designed to fail and costs a fortune to replace.
I've gone to using mini splits and windows units.

 

[Hohn]

This is why I hate central hvac. Its designed to fail and costs a fortune to replace.
I've gone to using mini splits and windows units.

I think if I ever have to buy A/C again (may it not be soon) that's almost certainly the route I will take.

 

[TooManyWheels]

....but you are much more efficient and comfortable than someone with even a two stage system. inverter systems are hard to beat if installed right.

It occurred to me that it might be possible to put numbers to this.

My initial assumption was that a system that modulated down to 25-30% capacity just *must* be having the coil warmer than the dewpoint. But Google, assuming it is correct, says a typical number for a system at the low end of it's capacity would be about 55 degrees. Plugging some typical interior temp and humidity figures for our house into a dewpoint calculator says anything lower than 60 is dehumidifying.

So I may be rethinking my preference for a two-stage condenser.

But now I'm wondering about the respective *rates* of dehumidification. I'm wondering if the house may get cool before it gets dry, having longer run times with a relatively warmer evaporator. Not to mention I'm still worried about the repair costs of a vastly more sophisticated system.

 

[BrendanC]

It occurred to me that it might be possible to put numbers to this.

My initial assumption was that a system that modulated down to 25-30% capacity just *must* be having the coil warmer than the dewpoint. But Google, assuming it is correct, says a typical number for a system at the low end of it's capacity would be about 55 degrees. Plugging some typical interior temp and humidity figures for our house into a dewpoint calculator says anything low than 60 is dehumidifying.

So I may be rethinking my preference for a two-stage condenser. Although I'm still worried about repair costs.

so that is actually something i tuned with my installs. you can set minimum inverter speed. i had to bump up from 15% to 20% to make sure the coil gets below dew point. my house was always 60-68% humidity. now i cruise in the mid 50’s and get down in the 40’s at night time when its set to 73°. keep in mind, this is a 1978 home (original owner was the GC so it isn’t built sloppy) that isnt up to new air seal/insulation code in Houston Texas.

 

[TooManyWheels]

so that is actually something i tuned with my installs. you can set minimum inverter speed. i had to bump up from 15% to 20% to make sure the coil gets below dew point. my house was always 60-68% humidity. now i cruise in the mid 50’s and get down in the 40’s at night time when its set to 73°. keep in mind, this is a 1978 home (original owner was the GC so it isn’t built sloppy) that isnt up to new air seal/insulation code in Houston Texas.

My home was built a year later, and has had similar humidity to yours. We're currently running a standalone dehumidifier, which runs most of the day to get it down to about 50%. Thanks for the note on the adjustment, that's very helpful.

 

[BrendanC]

My home was built a year later, and has had similar humidity to yours. We're currently running a standalone dehumidifier, which runs most of the day to get it down to about 50%.

time for an inverter central air system! i actually used to sleep at 70° but still in the 60% humidity. raised it to 73° and it feels the same if not a little better.