this post was submitted on 08 Aug 2024
45 points (100.0% liked)
Asklemmy
1452 readers
60 users here now
A loosely moderated place to ask open-ended questions
If your post meets the following criteria, it's welcome here!
- Open-ended question
- Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
- Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
- Not ad nauseam inducing: please make sure it is a question that would be new to most members
- An actual topic of discussion
Looking for support?
Looking for a community?
- Lemmyverse: community search
- sub.rehab: maps old subreddits to fediverse options, marks official as such
- !lemmy411@lemmy.ca: a community for finding communities
~Icon~ ~by~ ~@Double_A@discuss.tchncs.de~
founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
HVAC systems.
When my wife and I we had to replace our forced air furnace and central air system in the late autumn due to carbon monoxide literally the evening before our son was to be born, I felt under pressure to get something in place.
I told them I needed a more powerful air conditioner for all the unique heat-generating equipment in my basement, especially since our old system had trouble keeping up. They said that the new unit was more than enough for the square footage. I reiterated again, that air conditioners don't cool square footage, they cool BTU's, and the average home doesn't have a grow op and server farm in the basement generating significant heat. Then, they decided to hit me with the old "I've been doing this for {x} decades" speech.
Needless to say, I've had to consolidate servers, stop indoor gardening, replace the bulbs in the house with those shitty blue-hued LED's that can't dim right (and dimmer switches to handle the change in load characteristics), take the weather into account when cooking indoors and clean both sets of A/C coils on a more frequent basis. The air conditioner still can't keep up and when we have a string of hot days, we can't always count on the cooler evenings to get the house back down to "room temperature".
Oh, and now our old chimney drips water into the basement.
Without knowing the heat load calculation or what was installed it's obviously all guesses. But the fact that temps are easily reaching 40+ or 105+, no AC is going to transfer the heat from your house to the outdoors. It's basic science.
Air conditioners aren't actually cooling your house, but instead it's relocating heat. So if it's too hot outside, it won't do anything. heat transfer can only continue until the two objects (condenser outside and the ambient air) have reached thermal equilibrium and are at the same temperature. Once they balance out, it won't do anything.
Infact, getting MORE BTUs on your unit is actually a bad thing since it won't have time to dehumidify your house. This will lead to short cycling of the AC (it'll turn on and off a lot) and you never get cooling. The amount of homeowners that demanded bigger sizes units only to get pissed it's worse is astounding.
The indoor gardening also is TERRIBLE for air conditioners since your feeding so much moisture in the air.
You should look into variable speed compressors and the temps at which refrigerants work. You’re correct on many points but misinformed on others.
I know about inverter compressors, but they cannot defy the laws of thermo dynamics no matter how fast of slow they run. It's impossible. If it's too hot outside, the heat will not escape the condenser and will go right back inside rendering it useless and not cooling.
You will only see benefit with the inverter because it can slow down when it's not hot. If the compressor reaches 45degrees, and it's 40 degrees outside with the condenser in direct sun, you can't extracting much heat meaning it'll take forever to cool.
Refrigerant temps will make a difference, but they still have their limits too. All depends on what's being used. I assume OP was sold R410, low chance they were given the newer r32 or r454b replacements.
You’re just flatly wrong, the spec page for the humdrum mini split I pulled up first has a max outdoor max ambient operating temp of 52.78c (127f)
My point in bringing up refrigerant temps was to get you to look into it. Heat exchangers are more effective than you believe. No one is trying to convince you that these units defy the laws of physics.
The grow tent was mostly self-contained and humidity-controlled and monitored inside and out. It actually had to be indoors because of our short growing season, risk of germination from nearby industrial crops, and federal licensing requirements for the type of plant at the time. Regardless, the HVAC experts were here on-site and they could have opened their eyes to what I was telling them. There's was no heat load calculation. They said "this is the unit we install for your type of house and it's more than enough. Trust me, I've been doing this for..." etc. etc.
Of course condensers and evaporator coils work by pushing entropy around. I'm not sure what in my comment would have led you to believe I thought otherwise.
Short cycling would be a happy problem at this point. Over the past month the shortest cycle was on a 16 C day, when the A/C ran from 6:41am to 9:15am, and the longest were on those 32 C days when it started at roughly 7:45am and didn't finish cooling until 5am the next day. You suggest that it won't do anything on a hot day, but the temperature gradient indoors when the outside temperature is high is measurably lower when the system is cooling as compared to idle.
Maybe the HVAC guy was thinking I was just one of those same customers you're complaining about. Nobody's asking for a system ridiculously overpowered -- Just properly powered. I understand the value of properly sizing a system. For instance, I know that a properly-sized furnace should run nonstop on the coldest day of the year. I also know that you don't have an entire month's worth of "coldest day of the year"
My house can be 60 degree warmer than the outside temperature in the winter, so I just have to point the blame somewhere when it can't stay 10 degree cooler than the outside throughout summer. And yes, I know cooling is a lot more complex than heating, but I'm giving the A/C a 50 degree headstart.
...And that is why I think there should be a trial period for HVAC systems.