Anyone have knowledge on home A/C units?

[Haertig]

Did they give you a written quote with the breakdown for the new unit (manufacturer and part numbers) and any new parts or ducting or plumbing they will be including in the job?

No. But that's because before writing up the potential paths to repair/replacement on my quote, we had already verbally decided that the A/C was not going to be replaced. The tech's company asks them to write up all the options that were discussed. So I imagine for the replacement, which he knew we were not even remotely considering, he probably just put down a ballpark maximum assuming extensive work might need to be done. He didn't inspect my ductwork, etc., because he knew we weren't going down that path.

 

[Wyatt]

Does anyone here have home A/C maintenance/repair knowledge?

I'm trying to decide if we need a service call. On two occasions this year we have noticed that the outside copper going to the compressor is frosted over. I do not know if this indicates that the condenser inside is also frozen over. I have not taken the time to open up the inside unit to check for freezing (it's a little hard to get to). But since the house appears to be staying cool inside, my assumption is that it is not frozen. But maybe we've just gotten lucky and things have naturally started cooling off outside right at the same time our A/C has decided to freeze and not work. The condenser has frozen before (years ago), and the A/C tech adjusted the amount of coolant to fix that. IIRC, there seems to be a sweet spot for coolant level that makes the A/C work without freezing over.

When we noticed that the outside line was frosted, the inside of the house was still cool, right at the temperature we had the thermostat set to in one instance, and a single degree over in the other instance. Our setting is 72 degrees. Being in Colorado, we do not have gigantic A/C units like in the south. Ours is a 3 ton unit I believe, and our house is 2100 sq feet with a half basement in addition to that. If it's hot outside, our A/C has never been able to take the inside temperature down, but it can maintain it. e.g., if it's 92 outside, and we are set to 72 inside - and we turned the A/C on before it hit 72 inside - then the house will stay at 72. However, if we let the house climb to 74 before turning on the A/C when it's hot out, the best it can do is keep the house from rising further above 74, it won't bring it down to 72 until it cools off significantly outside. The temp coming our of our vents varies between 58 and 62 degrees (it's still in this range when the outside pipe is frosted over). This kind of follows the outside temp. Right now, it is 95 outside (I just took an accurate air temp reading at the A/C compressor location). And our vent temp is 61.5 degrees, with an airflow of 8 to 12 mph depending on where on the vent I am measuring (average is 9 mph). I am not equipped to measure the air volume, just the velocity. One other thing - we are very low humidity here. In the mornings we may rise to 30%, but by afternoon we're more typically 12-15%. Pretty dry most of the time.

OK. That's probably a lot of "we didn't need to know that" information about my A/C and local climate. Do I need a service call for the outside pipe occasionally frosting over assuming the A/C is still cooling the house appropriately? Obviously, if the house is no longer cooling then we need a service call. But if we do have a problem now, I'd rather catch and fix it before we're sitting inside in 80 degree heat wondering why we didn't call the A/C tech sooner!

Frosted:
View attachment 87931

Not frosted:
View attachment 87929

I called my son who is a master HVAC tech.

He informed me that low refrigerant and low airflow through the duct work will cause the frosting/freezing that you speak of.

He also informed me that a three-ton unit for a 2100 sq ft house is too small, unless the house is very well insulated.

If you are conditioning another 1000 sq ft of basement, it sounds like you need a larger unit.

 

[Haertig]

FWIW, after getting the refrigerant refilled two days ago, the air temp coming out of out vents is now 52 degrees. A marked improvement.

Thanks for the tip - when we do look at replacement of the A/C, we will look into the possibility of a larger unit.

 

[havasu]

6 years ago, I had my a/c replaced. I asked for a 5 ton, 18 seer (energy efficient), installed in my attic, with all new ducting, a wi-fi control panel, and new vents and baffles in all ducting. Total cost was $7995 installed.

This same unit today will cost you $15,000. I asked why the difference and he said supply was extremely limited, freon has doubled in price, his employees make twice as much. He also mentioned the gas prices were killing him, and still are.

 

[zoomzoom]

Sitting in my office right now.
93 degrees outside, 63 in my office.