Yet another AC issue

[Steve_R]

@Egnalf & others. We got a proposal to replace our HVAC system. 10 different options from two different manufacturers. All 3.5 ton capacity. Prices from $6,500 to $15k. Can anyone decipher the difference between these and recommend one?
.

[LisaJohn]

We had Daikins where I worked. I am not a fan of them. Maybe their residential is better. Amana option two is similar to our carrier quote. We are just waiting on them to get the unit in stock.

[Rodnok1]

They don't cover rot from salt air so not sure I'd care if warranty was longer than 10 years since you said they last about that long.
As for energy savings I'd try and do a quick number between extra cost up front vs 10 years and if you'd be living there then also.
I also look for parts costs/availability of them, nothing like a high end system that can't get parts for quickly. Doesn't matter if under warranty if they can't get the parts.

[benny42]

Originally Posted by Steve_R

@Egnalf & others. We got a proposal to replace our HVAC system. 10 different options from two different manufacturers. All 3.5 ton capacity. Prices from $6,500 to $15k. Can anyone decipher the difference between these and recommend one?
.

The truth is Amana and Daikin are the same company. Like Chevrolet and GMC. Both are good, sort of different option levels. Of the choices listed get the highest SEER you can comfortably afford. Decide soon, prices are going up soon. Disclaimer: I am in no way affiliated with the company that quoted you. I’m in the industry but not a residential company.

[Bill]

Originally Posted by benny42

The truth is Amana and Daikin are the same company. Like Chevrolet and GMC. Both are good, sort of different option levels. Of the choices listed get the highest SEER you can comfortably afford. Decide soon, prices are going up soon. Disclaimer: I am in no way affiliated with the company that quoted you. I’m in the industry but a residential company.

I'm still running my two 26 year old 12 seer units. With the Bidenflation spike in electric prices, I ran my all time highest bill ever, about $ 200 (I have gas, too). As long as I keep these guys running, am I going to ever save enough on running costs to justify 2 new units? I mean, in previous years, my Summer high bills were $ 140-150, much less in the non Summer months.

I am afraid new units won't last as long as the original Armstrong units have. One of them has never even been touched, other than checking freon level (never added any, just checked.)

[Egnalf]

Daikin is a very good brand comparable to Mitsubishi. Amana is owned by Daikin, but is made on the same line as Goodman. Two different philosophies toward HVAC, but one parent company.

SEER-- is the efficiency rating. Your old equipment is likely 10 or 12 seer if ten years old. As an example, a well installed system, properly sized and charged, should see a 6.5% energy savings per increase in seer. So going up from 12-18 seer should gain roughly 39% energy savings. It comes down to owner desire to be green, and payback. a 3 year payback on install cost is considered a sound investment. Beyond that, its really owner desire to save and willingess to pay upfront. calculator here: https://www.seerenergysavings.com/

two stage compressor--low speed, high speed. Running low speed during times of moderate weather saves energy and still gives comfort. current system is likely single speed
Variable speed compressor--speed varies with load. system runs near constant, with a desire for better comfert. it might only run at low speeds quite often. The desire is reduced energy via the cube rule. Read about it here: https://www.inverterdrivesystems.com/cube-law/

Variable speed air handler--allows fan speed to be ramped up and down with load. Also allows fan to be slowed down for better dehumidification in those climates which need it. Provides a soft start, slow ramping fan motor/controls. Eliminates the banging on/off like some systems have, and provides gentle air movement when starting . The main reason for this is to allow ramping up/down to provide constant comfort and keep the home much closer to setpoint than those systems which are on/off. Higher end occupants are picky like that ,and dont enjoy 1 or 2 degree swings.

The Daikin units show coated coils(which are rated for saltwater environments), the Amana does not.

Warranty on daikin is stout. 12 years. We use this brand often in commercial applications. for small server rooms, multi room installations, etc. Why I like them, A LOT:
1) Installed well, they rarely break
2) Excellent parts network, although rarely needed.
3) Manuals are posted at their website for anyone to download. (Most manufacturers hide their manuals).
4) We have had a great track record when using their equipment for over ten years.

[Egnalf]

Originally Posted by bill_daniels

I'm still running my two 26 year old 12 seer units. With the Bidenflation spike in electric prices, I ran my all time highest bill ever, about $ 200 (I have gas, too). As long as I keep these guys running, am I going to ever save enough on running costs to justify 2 new units? I mean, in previous years, my Summer high bills were $ 140-150, much less in the non Summer months.

I am afraid new units won't last as long as the original Armstrong units have. One of them has never even been touched, other than checking freon level (never added any, just checked.)

valid concern. planned obsolescence is a thing, for sure. Those old armstorng units are fricken tanks. The biggest issue you might have is phase of of refrigerant, but there are drop in replacements for now.

[Egnalf]

go here and click on resources, you will see what I mean. http://daikinac.com/

[Aerovette]

Originally Posted by Egnalf

valid concern. planned obsolescence is a thing, for sure. Those old armstorng units are fricken tanks. The biggest issue you might have is phase of of refrigerant, but there are drop in replacements for now.

Drop in replacements is a bit misleading. The system has to be evacuated first. They make it seem as though you can add one with the other. No, no, no.

[Egnalf]

Originally Posted by aerovette

Drop in replacements is a bit misleading. The system has to be evacuated first. They make it seem as though you can add one with the other. No, no, no.

Drop in refers to not having to change the compressor, oil, expansion device or other components. If you take issue with that call your politicians and file a complaint against the over reach of the EPA.

[Aerovette]

Originally Posted by Egnalf

Drop in refers to not having to change the compressor, oil, expansion device or other components. If you take issue with that call your politicians and file a complaint against the over reach of the EPA.

I only take issue with the wording used on the internet where the refrigerant is sold. It is made less than obvious that you cannot mix the two. I guess that allows the DIY people to ultimately still have to "call the guy" if they don't do their research.

What needs to be developed is an actual drop-in. We need to get back to the 89 cents a can days of R12 for cars and a dollar a pound for houses.

[Aerovette]

Update:

I went outside, pulled the sides off and fan off the unit and cleaned the coils.
I cleaned the inside coil best I could (not too accessible)
I added leak stop and 1.5lbs of R22

System is back to how it was. Not great, but ok.

BOTH upstairs and down are doing the same thing with temps.
I called "the guy" and he says in his 20 years, nothing I am saying about my system makes sense.

For BOTH units:

Set temp at 79 - it goes to 79
Set temp at 78 - it goes to 78
Set temp to 77 - it goes to 77
Set temp to 76 - it goes to 76
Set temp to 75 - it goes to 75
Set temp to 74 - it goes to 74
Set temp to 73 - it goes to 75 !!!

EVERY TIME I set the temp to 73, the temperature goes UP !!
The only time I can get to 73 is around 9:00PM or later.

Upstairs uses a Nest thermostat
Downstairs uses a Honeywell

[Egnalf]

Originally Posted by aerovette

Update:

I went outside, pulled the sides off and fan off the unit and cleaned the coils.
I cleaned the inside coil best I could (not too accessible)
I added leak stop and 1.5lbs of R22

System is back to how it was. Not great, but ok.

BOTH upstairs and down are doing the same thing with temps.
I called "the guy" and he says in his 20 years, nothing I am saying about my system makes sense.

For BOTH units:

Set temp at 79 - it goes to 79
Set temp at 78 - it goes to 78
Set temp to 77 - it goes to 77
Set temp to 76 - it goes to 76
Set temp to 75 - it goes to 75
Set temp to 74 - it goes to 74
Set temp to 73 - it goes to 75 !!!

EVERY TIME I set the temp to 73, the temperature goes UP !!
The only time I can get to 73 is around 9:00PM or later.

Upstairs uses a Nest thermostat
Downstairs uses a Honeywell

Undercharged

[Aerovette]

Originally Posted by Egnalf

Undercharged

Can you explain what is happening though?

A one degree drop should be easy to achieve.

Also, assuming undercharged, how is it able to take the system from 80 degrees all the way to 74, but NOT 73?

[LisaJohn]

This is what ours is doing. Thermo set on 72 and it will be 77-79 in the house. It holds 72-74 until 5 or 6 pm. Crazy! The guy said it’s some value that’s expensive to replace in addition to losing all the freon. And it’s 19 years old. So we are still waiting on the new one. We did buy a window unit to help out. Temp does not go back down until 3 or 4am.

[Egnalf]

Originally Posted by aerovette

Can you explain what is happening though?

A one degree drop should be easy to achieve.

Also, assuming undercharged, how is it able to take the system from 80 degrees all the way to 74, but NOT 73?

just a hunch since you refuse to take proper readings....if undercharged the refrigerant can start to flash in the liquid line. this drops pressure and cools the mix of vapor and liquid. you need a certain pressure to overcome the pressure drop through the orifice or thermostatic expansion valve and feed the coil properly. if not enough liquid feeding it your coil is warmer than desired, but still cool enough to do some work. as your temperature difference between the return air and coil get closer and closer, less work is done.

if you posted superheat and subcooling it would be easier to help you.

[LisaJohn]

Yes, the guy said expansion value and the coil was heating up. Thanks!

[Aerovette]

Originally Posted by Egnalf

just a hunch since you refuse to take proper readings....if undercharged the refrigerant can start to flash in the liquid line. this drops pressure and cools the mix of vapor and liquid. you need a certain pressure to overcome the pressure drop through the orifice or thermostatic expansion valve and feed the coil properly. if not enough liquid feeding it your coil is warmer than desired, but still cool enough to do some work. as your temperature difference between the return air and coil get closer and closer, less work is done.

if you posted superheat and subcooling it would be easier to help you.

I'll have "proper" gauges this weekend.

[Egnalf]

Originally Posted by LisaJohn

Yes, the guy said expansion value and the coil was heating up. Thanks!

Expansion valves go bad, but not frequently. Often the real problem is crud inside the system collecting at the inlet screen of the valve. A new valve is relatively inexpensive (under 100 bucks), you are paying for pumping down the refrigerant and labor to do the work of remove/replace, dehydrate and recharge the system. If there are valves at the outdoor unit to pump it down into itself its easier.

[Egnalf]

Originally Posted by aerovette

I'll have "proper" gauges this weekend.

Without knowing specs and conditions, you can shoot for targets if working alone. Try to get to 8-10 degrees subcooling at the exit of the outdoor unit, and 15-25 superheat at the inlet. If subcooling is below 3 or 4 degrees, its likely boiling off (flashing) in the liquid line before it gets to the indoor coil. Also, if there is a filter drier, check temperature/pressure across it, if possible. Pressure differential should be low, about 2 psi difference or less. Temperature should remain nearly constant from inlet to outlet. if neither of these is true, it could be getting clogged with crud.