Author Topic: 40° North, -105° West, 12:30 PM MDT, 100°F, 116VAC, RH 9%, A/C struggling  (Read 699 times)

230RN

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I can almost hear the voltage by the sound of the A/C fan.

Dayam, it's hot.  Screw the "but it's a dry heat" crap.

How you folks doing?

Terry

Brad Johnson

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100 F @ 9% RH? Sounds like a decent enough day, though on the warmer side.

I know you're using comic hyperbole to make a point, but if your A/C really is struggling at those temps, something is wrong.

Brad
It's all about the pancakes, people.
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 36.12°N 115.93°W  2700ft above sea level Winds NNE @ 1mph


106 degrees, 6% RH. heading to 110+ before the day is over. AC is doing just fine. Indoor temp 76 degrees. Walking outside is like walking into an oven.

At least it isn't Phoenix! :)

bob


Nick1911

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100 F @ 9% RH? Sounds like a decent enough day, though on the warmer side.

I know you're using comic hyperbole to make a point, but if your A/C really is struggling at those temps, something is wrong.

Brad

Eh, he's in Denver, yea?

ACCA 1% DB design temp for Denver is 90F.  So, yea, outdoor ambient is 10 degrees F above design temperature.  A properly sized and operating air conditioning system will be unable to maintain 75F indoors in those conditions.

Nick1911

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Kansas City.

High of 99F today, but it's only 90 at the moment.  Dewpoint is 68F.  It's hot and muggy out, no fun at all.

L1 voltage 120.47 VAC
L2 voltage 121.00 VAC

Return air temp 72F, 66.8% RH.
Supply air temp 54F, 99.9% RH.

Psycrometrics:

Brad Johnson

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ACCA 1% DB design temp for Denver is 90F.  So, yea, outdoor ambient is 10 degrees F above design temperature.  A properly sized and operating air conditioning system will be unable to maintain 75F indoors in those conditions.

Ick.

Denver is a plains city, especially on the eastern edge. Gets a damn sight hotter than 90 deg on a regular basis. Need to design for at least 100, maybe even 105.

Brad
It's all about the pancakes, people.
"And he thought cops wouldn't chase... a STOLEN DONUT TRUCK???? That would be like Willie Nelson ignoring a pickup full of weed."
-HankB

230RN

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In addition, the voltage on this side of the 220 A/C system is 116 volts.  Still within spec, but at the low edge.

Have no idea what the other side is, I'm just measuring it from the living room outlets.

ETA This is a "commercial" building (apartments) and I can't imagine them having them designed $5 more into anything.  Actually, a big problem is that I'm on the top floor, with an enormous volume of hot air stored in the attic up there, even overnight, and this radiates down through the ceiling... which is at 85°F at this moment.  (I also have a leaky hatch going up there, and you can feel the heat (and the cold in winter) under it.)

But all in all, this is a very comfortable apartment until it gets to extremes.

I'm sure as hell not going out today.

Terry
« Last Edit: June 17, 2021, 03:34:51 PM by 230RN »

Nick1911

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Ick.

Denver is a plains city, especially on the eastern edge. Gets a damn sight hotter than 90 deg on a regular basis. Need to design for at least 100, maybe even 105.

Brad

Maybe, but that's what the engineering tables show.  Wonder how often these are updated.

MechAg94

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Typical summer weather here.  It is hot and humid.  Not as dry as it could be due to recently rain.
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JTHunter

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According to the forecasters in St. Louis, they may break an old record today (Th) of 100o but will probably break Friday's record by 2-3 degrees (103 forecast).
And we have the humidity to go with it.
  [barf]
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88, 19% humidity. Comfortable 72 inside, and the AC hasn't kicked on yet. Probably won't till around 1600 or so. Supposed to hit 97 tomorrow.
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Jim147

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97 here 44% humidity and it's just about to get hot.

We do have a nice warm breeze.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

230RN

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 :laugh:
Way to go, Nick1911 !

 :rofl:

~3:40 PM MST.  This VAC side is up to 117, A/C sounds a little more robust.

I don't know how or if the power companies might roll back voltages in rotating areas, or is the voltage drop simply due to a heavier load in the lines --or in the apartment building itself (50 units, mostly stay-at-home retirees).

???

Nick1911

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:laugh:
Way to go, Nick1911 !

 :rofl:

I'll admit to cheating.  I've setup a wattnode to monitor power, which has a digispark bodged to it's RS485 output, exposing the data on the wifi network via REST.  That's being picked up and logged by a computer into a mysql database.

A more custom setup is on the HVAC stuff.  Dual pressure transducers for the refrigerant lines, temp sensors for the lines (so I can get superheat and subcooling), plus temp/humidity sensors in the duct system.  All also accessible over rest.

If I want to know what my system is doing, I can just hit it in my web browser. 
{"SupplyTemp":55.76, "SupplyHumidity":99.90, "ReturnTemp":69.98, "ReturnHumidity":70.10, "AnalogV1":1.20, "AnalogV2":2.49, "LineT1":96.80, "LineT2":61.70}

~3:40 PM MST.  This VAC side is up to 117, A/C sounds a little more robust.

I don't know how or if the power companies might roll back voltages in rotating areas, or is the voltage drop simply due to a heavier load in the lines --or in the apartment building itself (50 units, mostly stay-at-home retirees).

???

It's unlikey the power company would have any interest in lowering the voltage, particularly with lots of motor loads that will respond by increasing their current draw.  In my estimation, the voltage sag is just due to resistance in the infrastructure imposing some voltage drop on a day when demand is high.

Brad Johnson

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We're going to be dealing with related issues in a couple of weeks. One of our units is barely keeping up at what is considered moderate summer temps here. Based on temp deltas and the fact that it has worked properly in the past, I'm presuming it's likely low on refrigerant. It's right at 15 years old so it likely needs a top-off in addition to a good general cleaning and tune up.

Another issue is the return air duct being borderline too small. Unfortunately that isn't easily remedied as it's routed through the slab. It's only a two ton unit, but necessary air flow is still necessary air flow no matter what size air handler is involved.

Brad
It's all about the pancakes, people.
"And he thought cops wouldn't chase... a STOLEN DONUT TRUCK???? That would be like Willie Nelson ignoring a pickup full of weed."
-HankB

Jim147

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Airflow is key. On slab build installs people alway question why my returns are so big. I just say thT it needs to be that size.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

RoadKingLarry

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Current temp 96° F, 40% Rh, Dew point 67° F here.
My 15 y.o. grandson and I spent about 4 hours working on my boat this morning. About 11:00 AM it was 92° and he was starting to hint that he was getting too hot. I was working inthe sun rigging the masts, he was sanding teak under the bimini.  Wrapped it up and went swimming. Lake felt awesome.
Will probably work that schedule again tomorrow.
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Boomhauer

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I had to call the AC man to top off my system on Saturday night, he says it’s likely just a very very slow evaporator leak that needs attention every other year. Trying to eek out the most years from this elderly system as possible.
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Jim147

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I was not a fan of stop leaks until a couple years ago. Had an all refrigerator unit that I'm sure had a small evaporator leak but I couldn't find it with leak detector or bubbles even pumped up with nitrogen. Vacuumed it down shot in leak stop and charged. Worked great. Then he wanted a custom control put in so now it holds his beer at 32.

I need to order some more but can't remember the part number. Might have to call and ask and hope I don't get dumbasses.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

RoadKingLarry

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The wife's truck is in the shop for AC repair. It started leaking down last year. I had to jumper the compressor to get it to run so I could add Freon and stop leak the first time but after that I was adding a little about every two months. I kept after her to let me schedule it in to get it fixed while I was laid up with one of my surgeries but she didn't want to have to drive my Jeep. :facepalm:
Tried to charge it again a couple of weeks ago and had to jumper the compressor again. Appeared to take a charge but 3 days later it was flat again.
My recent new neighbor has a shop in town so I took it in to him Monday morning With the information that it was leaking down in a matter of days.
He turned it over to his mechanic. Tuesday afternoon I called and asked about it. He asked his mechanic who told him it had been finished Monday afternoon.
Went down to pick it Yesterday morning. Not a soul in the shop. Door was unlocked. I saw my key and the bill laying on the counter, Labor charge and charge for Freon. Went out and started the truck and no AC. :facepalm: :facepalm:
Called the neighbor, he was at the auto auction, and let him know what was going on. He said he'd make it right. Haven't heard anything since.

If ye love wealth better than liberty, the tranquility of servitude better than the animating contest of freedom, go home from us in peace. We ask not your counsels or your arms. Crouch down and lick the hands which feed you. May your chains set lightly upon you, and may posterity forget that you were our countrymen.

Samuel Adams

Jim147

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You can only top off a few times before you need a full vacuum and recharge. And schrader valves suck on automobiles.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

Boomhauer

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The wife's truck is in the shop for AC repair. It started leaking down last year. I had to jumper the compressor to get it to run so I could add Freon and stop leak the first time but after that I was adding a little about every two months. I kept after her to let me schedule it in to get it fixed while I was laid up with one of my surgeries but she didn't want to have to drive my Jeep. :facepalm:
Tried to charge it again a couple of weeks ago and had to jumper the compressor again. Appeared to take a charge but 3 days later it was flat again.
My recent new neighbor has a shop in town so I took it in to him Monday morning With the information that it was leaking down in a matter of days.
He turned it over to his mechanic. Tuesday afternoon I called and asked about it. He asked his mechanic who told him it had been finished Monday afternoon.
Went down to pick it Yesterday morning. Not a soul in the shop. Door was unlocked. I saw my key and the bill laying on the counter, Labor charge and charge for Freon. Went out and started the truck and no AC. :facepalm: :facepalm:
Called the neighbor, he was at the auto auction, and let him know what was going on. He said he'd make it right. Haven't heard anything since.



Said “mechanic” doesn’t know about AC troubleshooting or AC work and just shot it full of Freon and said it’s good.

Also avoid the stop leak it plugs up the recovery machines and stuff you don’t want to plug up in an AC machine.



Quote from: Ben
Holy hell. It's like giving a loaded gun to a chimpanzee...

Quote from: bluestarlizzard
the last thing you need is rabies. You're already angry enough as it is.

OTOH, there wouldn't be a tweeker left in Georgia...

Quote from: Balog
BLOOD FOR THE BLOOD GOD! SKULLS FOR THE SKULL THRONE! AND THROW SOME STEAK ON THE GRILL!

K Frame

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we've had a couple of days of absolutely gorgeous weather here. Moderate temperatures and low humidity. A gift this time of year in the metro Washington, DC, area.
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Same in Connecticut.  Absolutely gorgeous weather, haven't run the mini-splits in days.  We may get there tonight, though, and definitely this weekend.
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Bogie

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Stopleak basically just swells seals, gaskets and o-rings.
 
And you can only swell them so many times, so much, before they start to come apart.
 
Too many folks also "fill" the refrigerant past the proper level, at which point it has no room to expand, and therefore does not cool.
 
If your compressor takes a dump, you can't just replace it either - you have to do other stuff along the chain - the drier, expansion valves/tubes, and so on. I'd also put in fresh valves, etc. There are also sensors which tell the compressor when to come on. They'll require a vac and fill usually however. If your system gets vac'd, you replace a compressor, etc., make sure the proper amount of pag oil is added - some folks cheap on this, and then wonder why their $300 compressor with a few benjies worth of install just grenaded...

Damn, I almost sound like I know what I'm doing...
 
For a home AC unit, if you can put the outside part in shade, without tall grass, etc., around it, that will help. Also helps to hose it down a little - maybe at the edge of a lawn sprinkler.
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