Compressor location - sun / shade

[mortenaa]

Hi guys,

 

I'm currently building a house. And for aesthetic reasons, I will put a couple of the aircondition compressors on a flat section of the roof. My concern is that the compressors will be hit by the sun all day long, and might loose cooling ability. Should I be concerned about this, and build some kind of shade?  

Edited June 30, 2017 by mortenaa

[Crossy]

Shade would certainly do no harm.

 

In full sun everything will run hotter and have to work harder to expel the heat pumped out.

[Lamkyong]

best situated out of all adverse weather conditions if possible 

[eyecatcher]

I have seen several with a small offcut of their corrugated roof set up over them to deflect rainfall.

its seems they suffer from rust quite quickly

 

and for the sun...well maybe a hat?

[carlyai]

Sorry to be 'glass half empty', but I hope the flat section of the roof is not concrete, as some, tend to leak.

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[mortenaa]

18 hours ago, carlyai said:

Sorry to be 'glass half empty', but I hope the flat section of the roof is not concrete, as some, tend to leak.

Sent from my SM-J700F using Tapatalk
 

These guys have now built more than 60 houses, with the same design. No leaks to my knowledge.

[carlyai]

It's just me, but I would never put my compressor on a roof.
I say that having lived in Pattaya with houses around with compressors on the roof.
You probably aren't in a close housing build like I was. But as time goes by, they get noisier, and the plastic tubing and tape break down. Shoddy maintenance leaves a mess.
The green plastic cover over the units cracks and breaks down.
Rain and sun.


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[mortenaa]

14 minutes ago, carlyai said:

It's just me, but I would never put my compressor on a roof.
I say that having lived in Pattaya with houses around with compressors on the roof.
You probably aren't in a close housing build like I was. But as time goes by, they get noisier, and the plastic tubing and tape break down. Shoddy maintenance leaves a mess.
The green plastic cover over the units cracks and breaks down.
Rain and sun.


Sent from my SM-J700F using Tapatalk
 

Modern Inverters hardly make a sound. Plus my roof is double insulated, so thats not going to be an issue. Besides, they are so cheap now, that replacing them after 5-6 years is totally fine with me. But yeah, the rain and sun bothers me a bit. So I guess I have to make a small roof construction. 

[Pib]

Shade would be better as the condenser unit which houses the compressor would run cooler...making the A/C more efficient.

[mortenaa]

Just now, Pib said:

Shade would be better as the condenser unit which houses the compressor would run cooler...making the A/C more efficient.

 

I read a bit about it. The air temperature is what matters. The temperature in the air is about the same in the sun and the shade. Maybe 5% difference.
Anyway, I would have put the compressors on the north side of the house if I could, but its just too far.. 

[carlyai]

@mortenaa. You're probably right about modern inverters and noise.
It's not you I was worried about with the noise but the neighbours.
We had no worries with other people's on roof aircons. while inside the house, until we wanted to sit outside on the back balcony.

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[mortenaa]

I don't handle noise very well, and have double insulated the house, double glazed the windows etc. Done the same with my condo in BKK. But Im sitting on my balcony in my condo here in Bangkok, literally 1 meter away from the compressor. And aren't bothered at all. I would guess the sound level is around 30-40 db.

 

I have a neighbor only one one side, so she definitely won't be bothered. Maybe more so by the exhaust fan I plan to install on the roof

[Pib]

31 minutes ago, mortenaa said:

 

I read a bit about it. The air temperature is what matters. The temperature in the air is about the same in the sun and the shade. Maybe 5% difference.
Anyway, I would have put the compressors on the north side of the house if I could, but its just too far.. 

The sunlight beating down on the condenser unit will raise the temperature of the compressor within the condenser making the compressor  run hotter...less efficient.  How much less efficient I couldn't say.    The compressor is usually "enclosed" on one side of the condenser unit....kinda like in a "hot box" to protect  it and its electronics from the elements.   Although the compressor is circulating the refrigerant through the evaporator and condenser coils/fins which impacts the heat of the compressor, with the compressor operating within its "an enclosed hot box" so to speak direct sunlight makes that hot box hotter than if in the shade. 

 

But in many cases a person really can't choose a location with shade.  Like me....I have 7 A/Cs in/on my house....3 condenser units on the south side with no shade (and they will never have shade due to how my house is situated).....two on the north side with some shade....and two on the west side with shade.  Now I could relocate the 3 on the south side to the east side with good shade from a tree but the significantly longer  refrigerant piping  would have to be around 10 meters longer (the electrical wiring also)...this longer piping would cause a loss of A/C efficiency.

[mortenaa]

Just now, Pib said:

The sunlight beating down on the condenser unit will raise the temperature of the compressor within the condenser making the compressor  run hotter...less efficient.  How much less efficient I couldn't say.    The compressor is usually "enclosed" on one side of the condenser unit....kinda like in a "hot box" to protect  it and its electronics from the elements.   Although the compressor is circulating the refrigerant through the evaporator and condenser coils/fins which impacts the heat of the compressor, with the compressor operating within its "an enclosed hot box" so to speak direct sunlight makes that hot box hotter than if in the shade. 

 

But in many cases a person really can't choose a location with shade.  Like me....I have 7 A/Cs in/on my house....3 condenser units on the south side with no shade (and they will never have shade due to how my house is situated).....two on the north side with some shade....and two on the west side with shade.  Now I could relocate the 3 on the south side to the east side with good shade from a tree but the significantly longer  refrigerant piping  would have to be around 10 meters longer (the electrical wiring also)...this longer piping would cause a loss of A/C efficiency.

 

Thats what I originally thought as well, but seems like most articles and videos contradicts that.

http://www.energyvanguard.com/blog/will-shading-your-air-conditioner-save-you-money
 

[kannot]

stuck  both of  mine high under the eave s outta the sun /rain etc excuse photo just taken from USA via IP camera so night time  in Thailand

[sirineou]

I am sure most of you know this but let's recap

Air Conditioners work  via heat exchange.

A/C gas is compressed and heats up  hotter than ambient temperature and gives up heat to the surrounding area. then it is circulated inside where it decompresses becoming cooler than room temperature absorbing heat from the room., 

 That's how heat is removed from the room 

You want to keep the heat exchange fins on the compressor as cool as possible to facilitate maximum heat exchange, and placing them in the hot sun is not conducive toward that goal.

 

[mortenaa]

Anyone seen this before?

 

http://www.coolnsave.com

[klikster]

On 7/12/2017 at 8:15 PM, mortenaa said:

Anyone seen this before?

 

http://www.coolnsave.com

IMO, that looks like a "penny wise, pound foolish" approach. Water on aluminum fins will likely corrode them, which can create any number of problems.

[mortenaa]

On 8/1/2017 at 11:47 AM, klikster said:

IMO, that looks like a "penny wise, pound foolish" approach. Water on aluminum fins will likely corrode them, which can create any number of problems.

I agree with that. But there is a study (from the competitor) now showing 20% - 30$% saving. The competitor is smart solution, that measures the air etc, to apply just the amount of water needed to cool the air. 

[VocalNeal]

The AC unit is mounted in a white enclosure. It is already in the shade. Air movement is important so if the roof has a "wall" around it the unit should be above the wall for better circulation, then again it does have a fan. A small shade while not necessary will not hurt. 

 

Aluminium does not rust but forms an oxide layer which protects it from corrosion.  The misting idea will work but in most parts of Thailand in the hot season you will not get the unit down much below 27C as that is the evaporation temp.  Saijo Denki used to or still does make a unit with a water infused filter before the fins which is fed from a small trough. Called Grand Hybrid Inverter. It wouldn't hurt to run a water line to the roof for future use! 

 

Saijo Denki Hybrid System. 

 

 

 

Edited August 5, 2017 by VocalNeal

[Pib]

You are right...aluminum does not rust but it can corrode as you said which can cause damage to and pitting in the aluminum.   And when dealing with evaporators like in cars/trucks which are usually totally made of aluminum, not just the fins but the flat aluminum tubes with micro channels for the refrigerant to flow throw, develop leaks from corrosion/pitting.  

 

In home A/Cs almost always "copper" tubing is used for the refrigerant to flow through with aluminium fins (not carrying any refrigerant) wedged in between the copper tubes to greatly increase heat transfer/cooling as the air flow through the evaporator/condenser.   

 

And when I lived in Hawaii close to the ocean, corrosion did a number on my home A/C central air condenser fins made of aluminum...ate (corroded) portions away....the salt air created a good chemical reaction to corrode the aluminum.

 

http://www.allmetalsfab.com/does-aluminum-rust/

Quote

 

The terms rust and corrosion are often used interchangeably, but they’re not the same. Corrosion is a broad reference to the wearing away of metal caused by a chemical reaction. Rust is a type of corrosion referring specifically to the oxidation of iron or steel caused by interaction with water or moisture. So does aluminum corrode, or does aluminum rust?

Aluminum doesn’t contain iron or steel so it doesn’t rust – but it is prone to corrosion when exposed to weathering and atmospheric oxygen. The process of aluminum corrosion is known as oxidation. The resulting aluminum oxide is a thin, hard layer that actually protects the metal from further corrosion.

Aluminum oxide appears as a powdery white or dull gray coating. As oxidation occurs, it hardens and creates a protective layer over the newly exposed areas of corroded aluminum. The aluminum corrosion process is actually halted by oxidation – the metal won’t continue to deteriorate unless the aluminum oxide is removed. Unlike rust, which has a flaky, reddish appearance, aluminum oxidation cannot be easily chipped off the metal surface.

Aluminum oxidation occurs at different rates depending on the type of aluminum, the finish, and the environment surrounding the aluminum. Aluminum 5052, for example, is sometimes called The Hulk of aluminum alloys due to its durability and excellent corrosion resistance. Aluminum 3003, the most widely used of aluminum alloys, is also particularly good at resisting corrosion, but less favorable to anodizing, a factory process that mimics the natural process of oxidation to create a more durable metal with a corrosion-resistant aluminum finish.