Baby, It's Cold Outside, But Let's Talk A/C

[Sigarms]

Can you elaborate on this a bit more? Thanks!

All the best,

Peter

Peter

Very long story short...

In the past, all ratings given per SEER were done running the system at a .1 static pressure.

Everyone talks about pressures (per refrigerant) and gauges when it comes to a ducted HVAC system, but what it the most important variable IMO when servicing or starting up a ducted HVAC system is static pressure and air flow.

Lower the static pressure, the better.

I'd guess most ducted homes in the US run between a .60 and .80 static pressure. Anytime a blower motor or compressor fails within 5 years, FIRST thing that should be checked is static pressure. Anything running over .80 will most likely have future parts failures prematurely vs a system running under a .70.

Primary variable with negative affect on static pressure IMO is incorrect duct size.

Starting in 2023, not only will the SEER rating be increasing across the entire country, but the now manufactures will have to test their equipment running at a .50 static pressure than the current .10 static pressure.

The very long story, per the US government (keep in mind, this was all determined years ago)...

https://www.energy.gov/sites/prod/files/2016/11/f34/CAC_TP_Final_Rule.pdf

On a plus note, R410A has been given a stay of execution until 2025 when a couple of years ago it was supposed to end in 2023 as well.

Everyone complains about manufacturers, but you wouldn't believe how hard the government can make it for them.

 

[ponytug]

Thanks! That was very helpful. It would make sense to test the systems under more realistic conditions.

Slight change of subject: on an older furnace/AC system, are there any signs a capacitor is failing, or do they just go?

All the best,

Peter

 

[etpm]

Thanks! That was very helpful. It would make sense to test the systems under more realistic conditions.

Slight change of subject: on an older furnace/AC system, are there any signs a capacitor is failing, or do they just go?

All the best,

Peter

They usually just go. But if you have a motor that seems to be starting slow, and it spins freely when unpowered, then change the cap. Caps can fail slowly. And they ate cheap. So just replace questionable caps.
Eric

 

[ponytug]

Yes, that would describe the symptoms; hums and slowly starts up, but no obvious bearing issues. SWMBO thinks that it has always been like this, but I think it has been getting worse. Hence, my question.

Thanks!

All the best,

Peter

 

[kenmac]

The biggest equation I think you're missing isn't the actual efficiency rating, but that the the system will be rated at a .5 static vs a .1 static.

considering all they have done to try to meet energy code changes each time, making thinner copper coils for better heat transfer, micro channel, etc,. all that crap did is cause problems for everyone.

It's about all Manufactures can do, except change to inverter driven systems variable speed motors, and running DC. When you running @ say 20 HZ rather than 60 HZ theres no way conventional units can compete .

While I don't plan to get back into the game, these inverter driven systems, compressors running at a lower HZ have my interest .

 

[Larry Caldwell]

For my shop office I installed a heat/cool AC wall unit, not a split. It was only about $750. It uses the compressor for both heating and cooling, so is pretty efficient. I had to frame an outside wall penetration, but the interior of the unit sits flush with the wall, only protruding about 2". It came as a unit similar to a window shaker, so no special HVAC tools needed for installation.