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

[Diggin It]

Is it too early to talk about AC units?

I'm in the market for something. The 6K window shaker I have is several years old and not terribly efficient any more. I can't do central or heat pumps or anything similar for a number of reasons. Mini splits might be an option, but even the less expensive ones are close to a grand, plus installation. I know many of them are self install, but I don't have the gauges or evac tools required and I have concrete block walls to deal with.

Most of the window shakers I see don't have a fan that pulls in outside air for those cool nights. They usually only have a recirculation fan which doesn't help much. The one I have is narrow enough that I was able to rig up a way to let outside air in beside it when I want to.

So, bopping around the web this morning, I see this thing:

Midea MAW08V1QWT


8K BTU with a 15 SEER that looks like a self contained mini-split type gizmo. Let's you open and close the window as needed.

Probably not what I'll go with, but interesting.

Still looking. I need a remote too with auto-temp and timer settings which my 6K has.

 

[bdhsfz6]

I just installed a Daikin 15K ductless heat pump in my garage / workshop. It has a full featured remote control and timer. I hung the outside unit on brackets mounted to the block wall. I punched a 3" hole through the block with a hammer & chisel and mounted the indoor unit on the other side of the same wall. The unit comes pre-charged with gas and I rented a gauge set & vacuum pump from a local tool rental business.

The unit does not bring in outside air, it just recirculates. If I want fresh air, I open a window.

The project cost $2800 and took me 1 1/2 days to do. Smaller 7K units are available and are much cheaper. If you're handy with tools, it isn't that hard a job. The toughest part for me was getting the 100# outdoor unit up onto the wall brackets. I used the bucket of my tractor to do the lifting. This can be avoided if you put the unit on a slab at ground level but I didn't want to block the walkway.

 

[kenmac]

there are some mini split systems that don't require lines to be vacuumed.
Mr cool has such a unit. DIY.
Other than that, you're pretty much limited to a window shaker, which would be your cheapest option

 

[ericm979]

You can get an inverter AC window unit. Either U shaped or regular. Basically a cooling only mini split in a single unit.

 

[kenmac]

You can get an inverter AC window unit. Either U shaped or regular. Basically a cooling only mini split in a single unit.

yes, he can. The one he has pictured is, or can be inverter .
Due to efficiency codes, Won't be long, everything will be inverter

 

[ap0915]

I recently self installed a Mr Cool DIY unit. Hardest part of the install was running some romex through the crawl space for a new circuit.

An issue I had the the precharged lineset is that you apparently have to tighten it down, loosen it a turn and then retighten it in order for the valves to open up. Took a phone call to tech support to figure that out since it didn’t say that in the manual.

I’m also getting ready to get one of the LG inverter window units. A little pricey but should be worth the upgrade over a standard window unit.

 

[Jchonline]

there are some mini split systems that don't require lines to be vacuumed.
Mr cool has such a unit. DIY.
Other than that, you're pretty much limited to a window shaker, which would be your cheapest option

The lines are still vacuumed, they are just pre-charged by MrCool. If one ever needed service, they would have to vacuum them again.

 

[kenmac]

The lines are still vacuumed, they are just pre-charged by MrCool. If one ever needed service, they would have to vacuum them again.

correct. Point is, you don't have to vacuum to install

 

[Sigarms]

Due to efficiency codes, Won't be long, everything will be inverter

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.

 

[ponytug]

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.

Can you elaborate on this a bit more? Thanks!

All the best,

Peter

 

[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.